diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index 56721cc3f5c75..dd9590016b990 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -1,5 +1,8 @@
-use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
+use rustc_errors::{
+    Applicability, Diagnostic, DiagnosticBuilder, EmissionGuarantee, ErrorGuaranteed,
+};
 use rustc_hir as hir;
+use rustc_hir::intravisit::Visitor;
 use rustc_hir::Node;
 use rustc_middle::hir::map::Map;
 use rustc_middle::mir::{Mutability, Place, PlaceRef, ProjectionElem};
@@ -614,7 +617,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                             "trait `IndexMut` is required to modify indexed content, \
                                 but it is not implemented for `{ty}`",
                         ));
-                        self.suggest_map_index_mut_alternatives(ty, &mut err);
+                        self.suggest_map_index_mut_alternatives(ty, &mut err, span);
                     }
                     _ => (),
                 }
@@ -632,13 +635,120 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         &self,
         ty: Ty<'_>,
         err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>,
+        span: Span,
     ) {
         let Some(adt) = ty.ty_adt_def() else { return };
         let did = adt.did();
         if self.infcx.tcx.is_diagnostic_item(sym::HashMap, did)
             || self.infcx.tcx.is_diagnostic_item(sym::BTreeMap, did)
         {
-            err.help(format!("to modify a `{ty}`, use `.get_mut()`, `.insert()` or the entry API"));
+            struct V<'a, 'b, 'tcx, G: EmissionGuarantee> {
+                assign_span: Span,
+                err: &'a mut DiagnosticBuilder<'b, G>,
+                ty: Ty<'tcx>,
+                suggested: bool,
+            }
+            impl<'a, 'b: 'a, 'hir, 'tcx, G: EmissionGuarantee> Visitor<'hir> for V<'a, 'b, 'tcx, G> {
+                fn visit_stmt(&mut self, stmt: &'hir hir::Stmt<'hir>) {
+                    hir::intravisit::walk_stmt(self, stmt);
+                    let expr = match stmt.kind {
+                        hir::StmtKind::Semi(expr) | hir::StmtKind::Expr(expr) => expr,
+                        hir::StmtKind::Local(hir::Local { init: Some(expr), .. }) => expr,
+                        _ => {
+                            return;
+                        }
+                    };
+                    if let hir::ExprKind::Assign(place, rv, _sp) = expr.kind
+                        && let hir::ExprKind::Index(val, index) = place.kind
+                        && (expr.span == self.assign_span || place.span == self.assign_span)
+                    {
+                        // val[index] = rv;
+                        // ---------- place
+                        self.err.multipart_suggestions(
+                            &format!(
+                                "to modify a `{}`, use `.get_mut()`, `.insert()` or the entry API",
+                                self.ty,
+                            ),
+                            vec![
+                                vec![ // val.insert(index, rv);
+                                    (
+                                        val.span.shrink_to_hi().with_hi(index.span.lo()),
+                                        ".insert(".to_string(),
+                                    ),
+                                    (
+                                        index.span.shrink_to_hi().with_hi(rv.span.lo()),
+                                        ", ".to_string(),
+                                    ),
+                                    (rv.span.shrink_to_hi(), ")".to_string()),
+                                ],
+                                vec![ // val.get_mut(index).map(|v| { *v = rv; });
+                                    (
+                                        val.span.shrink_to_hi().with_hi(index.span.lo()),
+                                        ".get_mut(".to_string(),
+                                    ),
+                                    (
+                                        index.span.shrink_to_hi().with_hi(place.span.hi()),
+                                        ").map(|val| { *val".to_string(),
+                                    ),
+                                    (
+                                        rv.span.shrink_to_hi(),
+                                        "; })".to_string(),
+                                    ),
+                                ],
+                                vec![ // let x = val.entry(index).or_insert(rv);
+                                    (val.span.shrink_to_lo(), "let val = ".to_string()),
+                                    (
+                                        val.span.shrink_to_hi().with_hi(index.span.lo()),
+                                        ".entry(".to_string(),
+                                    ),
+                                    (
+                                        index.span.shrink_to_hi().with_hi(rv.span.lo()),
+                                        ").or_insert(".to_string(),
+                                    ),
+                                    (rv.span.shrink_to_hi(), ")".to_string()),
+                                ],
+                            ].into_iter(),
+                            Applicability::MachineApplicable,
+                        );
+                        self.suggested = true;
+                    } else if let hir::ExprKind::MethodCall(_path, args @ [_, ..], sp) = expr.kind
+                        && let hir::ExprKind::Index(val, index) = args[0].kind
+                        && expr.span == self.assign_span
+                    {
+                        // val[index].path(args..);
+                        self.err.multipart_suggestion(
+                            &format!("to modify a `{}` use `.get_mut()`", self.ty),
+                            vec![
+                                (
+                                    val.span.shrink_to_hi().with_hi(index.span.lo()),
+                                    ".get_mut(".to_string(),
+                                ),
+                                (
+                                    index.span.shrink_to_hi().with_hi(args[0].span.hi()),
+                                    ").map(|val| val".to_string(),
+                                ),
+                                (sp.shrink_to_hi(), ")".to_string()),
+                            ],
+                            Applicability::MachineApplicable,
+                        );
+                        self.suggested = true;
+                    }
+                }
+            }
+            let hir_map = self.infcx.tcx.hir();
+            let def_id = self.body.source.def_id();
+            let hir_id = hir_map.local_def_id_to_hir_id(def_id.as_local().unwrap());
+            let node = hir_map.find(hir_id);
+            let Some(hir::Node::Item(item)) = node else { return; };
+            let hir::ItemKind::Fn(.., body_id) = item.kind else { return; };
+            let body = self.infcx.tcx.hir().body(body_id);
+            let mut v = V { assign_span: span, err, ty, suggested: false };
+            v.visit_body(body);
+            if !v.suggested {
+                err.help(&format!(
+                    "to modify a `{ty}`, use `.get_mut()`, `.insert()` or the entry API",
+                ));
+            }
         }
     }
 
diff --git a/compiler/rustc_error_messages/locales/en-US/incremental.ftl b/compiler/rustc_error_messages/locales/en-US/incremental.ftl
new file mode 100644
index 0000000000000..ed9a22c02d181
--- /dev/null
+++ b/compiler/rustc_error_messages/locales/en-US/incremental.ftl
@@ -0,0 +1,106 @@
+incremental_unrecognized_depnode = unrecognized `DepNode` variant: {$name}
+
+incremental_missing_depnode = missing `DepNode` variant
+
+incremental_missing_if_this_changed = no `#[rustc_if_this_changed]` annotation detected
+
+incremental_no_path = no path from `{$source}` to `{$target}`
+
+incremental_ok = OK
+
+incremental_unknown_reuse_kind = unknown cgu-reuse-kind `{$kind}` specified
+
+incremental_missing_query_depgraph = found CGU-reuse attribute but `-Zquery-dep-graph` was not specified
+
+incremental_malformed_cgu_name =
+    found malformed codegen unit name `{$user_path}`. codegen units names must always start with the name of the crate (`{$crate_name}` in this case).
+
+incremental_no_module_named = no module named `{$user_path}` (mangled: {$cgu_name}). available modules: {$cgu_names}
+
+incremental_field_associated_value_expected = associated value expected for `{$name}`
+
+incremental_no_field = no field `{$name}`
+
+incremental_assertion_auto = `except` specified DepNodes that can not be affected for \"{$name}\": \"{$e}\"
+
+incremental_undefined_clean_dirty_assertions_item = clean/dirty auto-assertions not yet defined for Node::Item.node={$kind}
+
+incremental_undefined_clean_dirty_assertions = clean/dirty auto-assertions not yet defined for {$kind}
+
+incremental_repeated_depnode_label = dep-node label `{$label}` is repeated
+
+incremental_unrecognized_depnode_label = dep-node label `{$label}` not recognized
+
+incremental_not_dirty = `{$dep_node_str}` should be dirty but is not
+
+incremental_not_clean = `{$dep_node_str}` should be clean but is not
+
+incremental_not_loaded = `{$dep_node_str}` should have been loaded from disk but it was not
+
+incremental_unknown_item = unknown item `{$name}`
+
+incremental_no_cfg = no cfg attribute
+
+incremental_associated_value_expected_for = associated value expected for `{$ident}`
+
+incremental_associated_value_expected = expected an associated value
+
+incremental_unchecked_clean = found unchecked `#[rustc_clean]` attribute
+
+incremental_delete_old = unable to delete old {$name} at `{$path}`: {$err}
+
+incremental_create_new = failed to create {$name} at `{$path}`: {$err}
+
+incremental_write_new = failed to write {$name} to `{$path}`: {$err}
+
+incremental_canonicalize_path = incremental compilation: error canonicalizing path `{$path}`: {$err}
+
+incremental_create_incr_comp_dir = could not create incremental compilation {$tag} directory `{$path}`: {$err}
+
+incremental_create_lock = incremental compilation: could not create session directory lock file: {$lock_err}
+    .lock_unsupported = the filesystem for the incremental path at {$session_dir} does not appear to support locking, consider changing the incremental path to a filesystem that supports locking or disable incremental compilation
+    .cargo_help_1 = incremental compilation can be disabled by setting the environment variable CARGO_INCREMENTAL=0 (see https://doc.rust-lang.org/cargo/reference/profiles.html#incremental)
+    .cargo_help_2 = the entire build directory can be changed to a different filesystem by setting the environment variable CARGO_TARGET_DIR to a different path (see https://doc.rust-lang.org/cargo/reference/config.html#buildtarget-dir)
+
+incremental_delete_lock = error deleting lock file for incremental compilation session directory `{$path}`: {$err}
+
+incremental_hard_link_failed =
+    hard linking files in the incremental compilation cache failed. copying files instead. consider moving the cache directory to a file system which supports hard linking in session dir `{$path}`
+
+incremental_delete_partial = failed to delete partly initialized session dir `{$path}`: {$err}
+
+incremental_delete_full = error deleting incremental compilation session directory `{$path}`: {$err}
+
+incremental_finalize = error finalizing incremental compilation session directory `{$path}`: {$err}
+
+incremental_invalid_gc_failed =
+    failed to garbage collect invalid incremental compilation session directory `{$path}`: {$err}
+
+incremental_finalized_gc_failed =
+    failed to garbage collect finalized incremental compilation session directory `{$path}`: {$err}
+
+incremental_session_gc_failed =
+    failed to garbage collect incremental compilation session directory `{$path}`: {$err}
+
+incremental_assert_not_loaded =
+    we asserted that the incremental cache should not be loaded, but it was loaded
+
+incremental_assert_loaded =
+    we asserted that an existing incremental cache directory should be successfully loaded, but it was not
+
+incremental_delete_incompatible =
+    failed to delete invalidated or incompatible incremental compilation session directory contents `{$path}`: {$err}
+
+incremental_load_dep_graph = could not load dep-graph from `{$path}`: {$err}
+
+incremental_decode_incr_cache = could not decode incremental cache: {$err}
+
+incremental_write_dep_graph = failed to write dependency graph to `{$path}`: {$err}
+
+incremental_move_dep_graph = failed to move dependency graph from `{$from}` to `{$to}`: {$err}
+
+incremental_create_dep_graph = failed to create dependency graph at `{$path}`: {$err}
+
+incremental_copy_workproduct_to_cache = error copying object file `{$from}` to incremental directory as `{$to}`: {$err}
+
+incremental_delete_workproduct = file-system error deleting outdated file `{$path}`: {$err}
diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index b18d1f553e499..daaf65ef7d993 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -40,6 +40,7 @@ fluent_messages! {
     const_eval => "../locales/en-US/const_eval.ftl",
     driver => "../locales/en-US/driver.ftl",
     expand => "../locales/en-US/expand.ftl",
+    incremental => "../locales/en-US/incremental.ftl",
     interface => "../locales/en-US/interface.ftl",
     lint => "../locales/en-US/lint.ftl",
     parser => "../locales/en-US/parser.ftl",
diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index 506198df4d8ed..f75e2596f361b 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -686,19 +686,12 @@ impl Diagnostic {
         suggestion: Vec<(Span, String)>,
         applicability: Applicability,
     ) -> &mut Self {
-        assert!(!suggestion.is_empty());
-        self.push_suggestion(CodeSuggestion {
-            substitutions: vec![Substitution {
-                parts: suggestion
-                    .into_iter()
-                    .map(|(span, snippet)| SubstitutionPart { snippet, span })
-                    .collect(),
-            }],
-            msg: self.subdiagnostic_message_to_diagnostic_message(msg),
-            style: SuggestionStyle::CompletelyHidden,
+        self.multipart_suggestion_with_style(
+            msg,
+            suggestion,
             applicability,
-        });
-        self
+            SuggestionStyle::CompletelyHidden,
+        )
     }
 
     /// Prints out a message with a suggested edit of the code.
diff --git a/compiler/rustc_incremental/src/assert_dep_graph.rs b/compiler/rustc_incremental/src/assert_dep_graph.rs
index 69e482ce854c0..95b48c38218d0 100644
--- a/compiler/rustc_incremental/src/assert_dep_graph.rs
+++ b/compiler/rustc_incremental/src/assert_dep_graph.rs
@@ -33,6 +33,7 @@
 //! fn baz() { foo(); }
 //! ```
 
+use crate::errors;
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::graph::implementation::{Direction, NodeIndex, INCOMING, OUTGOING};
@@ -133,12 +134,10 @@ impl<'tcx> IfThisChanged<'tcx> {
                     Some(n) => {
                         match DepNode::from_label_string(self.tcx, n.as_str(), def_path_hash) {
                             Ok(n) => n,
-                            Err(()) => {
-                                self.tcx.sess.span_fatal(
-                                    attr.span,
-                                    &format!("unrecognized DepNode variant {:?}", n),
-                                );
-                            }
+                            Err(()) => self.tcx.sess.emit_fatal(errors::UnrecognizedDepNode {
+                                span: attr.span,
+                                name: n,
+                            }),
                         }
                     }
                 };
@@ -149,16 +148,14 @@ impl<'tcx> IfThisChanged<'tcx> {
                     Some(n) => {
                         match DepNode::from_label_string(self.tcx, n.as_str(), def_path_hash) {
                             Ok(n) => n,
-                            Err(()) => {
-                                self.tcx.sess.span_fatal(
-                                    attr.span,
-                                    &format!("unrecognized DepNode variant {:?}", n),
-                                );
-                            }
+                            Err(()) => self.tcx.sess.emit_fatal(errors::UnrecognizedDepNode {
+                                span: attr.span,
+                                name: n,
+                            }),
                         }
                     }
                     None => {
-                        self.tcx.sess.span_fatal(attr.span, "missing DepNode variant");
+                        self.tcx.sess.emit_fatal(errors::MissingDepNode { span: attr.span });
                     }
                 };
                 self.then_this_would_need.push((
@@ -204,7 +201,7 @@ fn check_paths<'tcx>(tcx: TyCtxt<'tcx>, if_this_changed: &Sources, then_this_wou
     // Return early here so as not to construct the query, which is not cheap.
     if if_this_changed.is_empty() {
         for &(target_span, _, _, _) in then_this_would_need {
-            tcx.sess.span_err(target_span, "no `#[rustc_if_this_changed]` annotation detected");
+            tcx.sess.emit_err(errors::MissingIfThisChanged { span: target_span });
         }
         return;
     }
@@ -213,16 +210,13 @@ fn check_paths<'tcx>(tcx: TyCtxt<'tcx>, if_this_changed: &Sources, then_this_wou
             let dependents = query.transitive_predecessors(source_dep_node);
             for &(target_span, ref target_pass, _, ref target_dep_node) in then_this_would_need {
                 if !dependents.contains(&target_dep_node) {
-                    tcx.sess.span_err(
-                        target_span,
-                        &format!(
-                            "no path from `{}` to `{}`",
-                            tcx.def_path_str(source_def_id),
-                            target_pass
-                        ),
-                    );
+                    tcx.sess.emit_err(errors::NoPath {
+                        span: target_span,
+                        source: tcx.def_path_str(source_def_id),
+                        target: *target_pass,
+                    });
                 } else {
-                    tcx.sess.span_err(target_span, "OK");
+                    tcx.sess.emit_err(errors::Ok { span: target_span });
                 }
             }
         }
diff --git a/compiler/rustc_incremental/src/assert_module_sources.rs b/compiler/rustc_incremental/src/assert_module_sources.rs
index 89d419bc8e90f..2968a0e1203a9 100644
--- a/compiler/rustc_incremental/src/assert_module_sources.rs
+++ b/compiler/rustc_incremental/src/assert_module_sources.rs
@@ -22,6 +22,7 @@
 //! allows for doing a more fine-grained check to see if pre- or post-lto data
 //! was re-used.
 
+use crate::errors;
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def_id::LOCAL_CRATE;
@@ -66,10 +67,9 @@ impl<'tcx> AssertModuleSource<'tcx> {
                 sym::post_dash_lto => (CguReuse::PostLto, ComparisonKind::Exact),
                 sym::any => (CguReuse::PreLto, ComparisonKind::AtLeast),
                 other => {
-                    self.tcx.sess.span_fatal(
-                        attr.span,
-                        &format!("unknown cgu-reuse-kind `{}` specified", other),
-                    );
+                    self.tcx
+                        .sess
+                        .emit_fatal(errors::UnknownReuseKind { span: attr.span, kind: other });
                 }
             }
         } else {
@@ -77,10 +77,7 @@ impl<'tcx> AssertModuleSource<'tcx> {
         };
 
         if !self.tcx.sess.opts.unstable_opts.query_dep_graph {
-            self.tcx.sess.span_fatal(
-                attr.span,
-                "found CGU-reuse attribute but `-Zquery-dep-graph` was not specified",
-            );
+            self.tcx.sess.emit_fatal(errors::MissingQueryDepGraph { span: attr.span });
         }
 
         if !self.check_config(attr) {
@@ -92,13 +89,11 @@ impl<'tcx> AssertModuleSource<'tcx> {
         let crate_name = self.tcx.crate_name(LOCAL_CRATE).to_string();
 
         if !user_path.starts_with(&crate_name) {
-            let msg = format!(
-                "Found malformed codegen unit name `{}`. \
-                Codegen units names must always start with the name of the \
-                crate (`{}` in this case).",
-                user_path, crate_name
-            );
-            self.tcx.sess.span_fatal(attr.span, &msg);
+            self.tcx.sess.emit_fatal(errors::MalformedCguName {
+                span: attr.span,
+                user_path,
+                crate_name,
+            });
         }
 
         // Split of the "special suffix" if there is one.
@@ -125,15 +120,12 @@ impl<'tcx> AssertModuleSource<'tcx> {
             let mut cgu_names: Vec<&str> =
                 self.available_cgus.iter().map(|cgu| cgu.as_str()).collect();
             cgu_names.sort();
-            self.tcx.sess.span_err(
-                attr.span,
-                &format!(
-                    "no module named `{}` (mangled: {}). Available modules: {}",
-                    user_path,
-                    cgu_name,
-                    cgu_names.join(", ")
-                ),
-            );
+            self.tcx.sess.emit_err(errors::NoModuleNamed {
+                span: attr.span,
+                user_path,
+                cgu_name,
+                cgu_names: cgu_names.join(", "),
+            });
         }
 
         self.tcx.sess.cgu_reuse_tracker.set_expectation(
@@ -151,15 +143,15 @@ impl<'tcx> AssertModuleSource<'tcx> {
                 if let Some(value) = item.value_str() {
                     return value;
                 } else {
-                    self.tcx.sess.span_fatal(
-                        item.span(),
-                        &format!("associated value expected for `{}`", name),
-                    );
+                    self.tcx.sess.emit_fatal(errors::FieldAssociatedValueExpected {
+                        span: item.span(),
+                        name,
+                    });
                 }
             }
         }
 
-        self.tcx.sess.span_fatal(attr.span, &format!("no field `{}`", name));
+        self.tcx.sess.emit_fatal(errors::NoField { span: attr.span, name });
     }
 
     /// Scan for a `cfg="foo"` attribute and check whether we have a
diff --git a/compiler/rustc_incremental/src/errors.rs b/compiler/rustc_incremental/src/errors.rs
new file mode 100644
index 0000000000000..a15cff22f8756
--- /dev/null
+++ b/compiler/rustc_incremental/src/errors.rs
@@ -0,0 +1,364 @@
+use rustc_macros::SessionDiagnostic;
+use rustc_span::{symbol::Ident, Span, Symbol};
+use std::path::{Path, PathBuf};
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::unrecognized_depnode)]
+pub struct UnrecognizedDepNode {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::missing_depnode)]
+pub struct MissingDepNode {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::missing_if_this_changed)]
+pub struct MissingIfThisChanged {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::ok)]
+pub struct Ok {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::no_path)]
+pub struct NoPath {
+    #[primary_span]
+    pub span: Span,
+    pub target: Symbol,
+    pub source: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::unknown_reuse_kind)]
+pub struct UnknownReuseKind {
+    #[primary_span]
+    pub span: Span,
+    pub kind: Symbol,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::missing_query_depgraph)]
+pub struct MissingQueryDepGraph {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::malformed_cgu_name)]
+pub struct MalformedCguName {
+    #[primary_span]
+    pub span: Span,
+    pub user_path: String,
+    pub crate_name: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::no_module_named)]
+pub struct NoModuleNamed<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub user_path: &'a str,
+    pub cgu_name: Symbol,
+    pub cgu_names: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::field_associated_value_expected)]
+pub struct FieldAssociatedValueExpected {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::no_field)]
+pub struct NoField {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::assertion_auto)]
+pub struct AssertionAuto<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub name: &'a str,
+    pub e: &'a str,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::undefined_clean_dirty_assertions_item)]
+pub struct UndefinedCleanDirtyItem {
+    #[primary_span]
+    pub span: Span,
+    pub kind: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::undefined_clean_dirty_assertions)]
+pub struct UndefinedCleanDirty {
+    #[primary_span]
+    pub span: Span,
+    pub kind: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::repeated_depnode_label)]
+pub struct RepeatedDepNodeLabel<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub label: &'a str,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::unrecognized_depnode_label)]
+pub struct UnrecognizedDepNodeLabel<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub label: &'a str,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::not_dirty)]
+pub struct NotDirty<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub dep_node_str: &'a str,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::not_clean)]
+pub struct NotClean<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub dep_node_str: &'a str,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::not_loaded)]
+pub struct NotLoaded<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub dep_node_str: &'a str,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::unknown_item)]
+pub struct UnknownItem {
+    #[primary_span]
+    pub span: Span,
+    pub name: Symbol,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::no_cfg)]
+pub struct NoCfg {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::associated_value_expected_for)]
+pub struct AssociatedValueExpectedFor {
+    #[primary_span]
+    pub span: Span,
+    pub ident: Ident,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::associated_value_expected)]
+pub struct AssociatedValueExpected {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::unchecked_clean)]
+pub struct UncheckedClean {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::delete_old)]
+pub struct DeleteOld<'a> {
+    pub name: &'a str,
+    pub path: PathBuf,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::create_new)]
+pub struct CreateNew<'a> {
+    pub name: &'a str,
+    pub path: PathBuf,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::write_new)]
+pub struct WriteNew<'a> {
+    pub name: &'a str,
+    pub path: PathBuf,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::canonicalize_path)]
+pub struct CanonicalizePath {
+    pub path: PathBuf,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::create_incr_comp_dir)]
+pub struct CreateIncrCompDir<'a> {
+    pub tag: &'a str,
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::create_lock)]
+pub struct CreateLock<'a> {
+    pub lock_err: std::io::Error,
+    pub session_dir: &'a Path,
+    #[note(incremental::lock_unsupported)]
+    pub is_unsupported_lock: Option<()>,
+    #[help(incremental::cargo_help_1)]
+    #[help(incremental::cargo_help_2)]
+    pub is_cargo: Option<()>,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::delete_lock)]
+pub struct DeleteLock<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::hard_link_failed)]
+pub struct HardLinkFailed<'a> {
+    pub path: &'a Path,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::delete_partial)]
+pub struct DeletePartial<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::delete_full)]
+pub struct DeleteFull<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::finalize)]
+pub struct Finalize<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::invalid_gc_failed)]
+pub struct InvalidGcFailed<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::finalized_gc_failed)]
+pub struct FinalizedGcFailed<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::session_gc_failed)]
+pub struct SessionGcFailed<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::assert_not_loaded)]
+pub struct AssertNotLoaded;
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::assert_loaded)]
+pub struct AssertLoaded;
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::delete_incompatible)]
+pub struct DeleteIncompatible {
+    pub path: PathBuf,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::load_dep_graph)]
+pub struct LoadDepGraph {
+    pub path: PathBuf,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::decode_incr_cache)]
+pub struct DecodeIncrCache {
+    pub err: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::write_dep_graph)]
+pub struct WriteDepGraph<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::move_dep_graph)]
+pub struct MoveDepGraph<'a> {
+    pub from: &'a Path,
+    pub to: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::create_dep_graph)]
+pub struct CreateDepGraph<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::copy_workproduct_to_cache)]
+pub struct CopyWorkProductToCache<'a> {
+    pub from: &'a Path,
+    pub to: &'a Path,
+    pub err: std::io::Error,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(incremental::delete_workproduct)]
+pub struct DeleteWorkProduct<'a> {
+    pub path: &'a Path,
+    pub err: std::io::Error,
+}
diff --git a/compiler/rustc_incremental/src/lib.rs b/compiler/rustc_incremental/src/lib.rs
index 1e88e8091c373..dc4a80519247b 100644
--- a/compiler/rustc_incremental/src/lib.rs
+++ b/compiler/rustc_incremental/src/lib.rs
@@ -3,8 +3,11 @@
 #![deny(missing_docs)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(let_else)]
+#![feature(never_type)]
 #![recursion_limit = "256"]
 #![allow(rustc::potential_query_instability)]
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 
 #[macro_use]
 extern crate rustc_middle;
@@ -13,6 +16,7 @@ extern crate tracing;
 
 mod assert_dep_graph;
 pub mod assert_module_sources;
+mod errors;
 mod persist;
 
 use assert_dep_graph::assert_dep_graph;
diff --git a/compiler/rustc_incremental/src/persist/dirty_clean.rs b/compiler/rustc_incremental/src/persist/dirty_clean.rs
index 710c4a01b244f..4c815d69ff395 100644
--- a/compiler/rustc_incremental/src/persist/dirty_clean.rs
+++ b/compiler/rustc_incremental/src/persist/dirty_clean.rs
@@ -19,6 +19,7 @@
 //! Errors are reported if we are in the suitable configuration but
 //! the required condition is not met.
 
+use crate::errors;
 use rustc_ast::{self as ast, Attribute, NestedMetaItem};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def_id::LocalDefId;
@@ -198,11 +199,7 @@ impl<'tcx> DirtyCleanVisitor<'tcx> {
         let loaded_from_disk = self.loaded_from_disk(attr);
         for e in except.iter() {
             if !auto.remove(e) {
-                let msg = format!(
-                    "`except` specified DepNodes that can not be affected for \"{}\": \"{}\"",
-                    name, e
-                );
-                self.tcx.sess.span_fatal(attr.span, &msg);
+                self.tcx.sess.emit_fatal(errors::AssertionAuto { span: attr.span, name, e });
             }
         }
         Assertion { clean: auto, dirty: except, loaded_from_disk }
@@ -284,14 +281,10 @@ impl<'tcx> DirtyCleanVisitor<'tcx> {
                     // An implementation, eg `impl<A> Trait for Foo { .. }`
                     HirItem::Impl { .. } => ("ItemKind::Impl", LABELS_IMPL),
 
-                    _ => self.tcx.sess.span_fatal(
-                        attr.span,
-                        &format!(
-                            "clean/dirty auto-assertions not yet defined \
-                             for Node::Item.node={:?}",
-                            item.kind
-                        ),
-                    ),
+                    _ => self.tcx.sess.emit_fatal(errors::UndefinedCleanDirtyItem {
+                        span: attr.span,
+                        kind: format!("{:?}", item.kind),
+                    }),
                 }
             }
             HirNode::TraitItem(item) => match item.kind {
@@ -304,10 +297,10 @@ impl<'tcx> DirtyCleanVisitor<'tcx> {
                 ImplItemKind::Const(..) => ("NodeImplConst", LABELS_CONST_IN_IMPL),
                 ImplItemKind::TyAlias(..) => ("NodeImplType", LABELS_CONST_IN_IMPL),
             },
-            _ => self.tcx.sess.span_fatal(
-                attr.span,
-                &format!("clean/dirty auto-assertions not yet defined for {:?}", node),
-            ),
+            _ => self.tcx.sess.emit_fatal(errors::UndefinedCleanDirty {
+                span: attr.span,
+                kind: format!("{:?}", node),
+            }),
         };
         let labels =
             Labels::from_iter(labels.iter().flat_map(|s| s.iter().map(|l| (*l).to_string())));
@@ -320,16 +313,15 @@ impl<'tcx> DirtyCleanVisitor<'tcx> {
             let label = label.trim();
             if DepNode::has_label_string(label) {
                 if out.contains(label) {
-                    self.tcx.sess.span_fatal(
-                        item.span(),
-                        &format!("dep-node label `{}` is repeated", label),
-                    );
+                    self.tcx
+                        .sess
+                        .emit_fatal(errors::RepeatedDepNodeLabel { span: item.span(), label });
                 }
                 out.insert(label.to_string());
             } else {
                 self.tcx
                     .sess
-                    .span_fatal(item.span(), &format!("dep-node label `{}` not recognized", label));
+                    .emit_fatal(errors::UnrecognizedDepNodeLabel { span: item.span(), label });
             }
         }
         out
@@ -350,7 +342,7 @@ impl<'tcx> DirtyCleanVisitor<'tcx> {
             let dep_node_str = self.dep_node_str(&dep_node);
             self.tcx
                 .sess
-                .span_err(item_span, &format!("`{}` should be dirty but is not", dep_node_str));
+                .emit_err(errors::NotDirty { span: item_span, dep_node_str: &dep_node_str });
         }
     }
 
@@ -361,7 +353,7 @@ impl<'tcx> DirtyCleanVisitor<'tcx> {
             let dep_node_str = self.dep_node_str(&dep_node);
             self.tcx
                 .sess
-                .span_err(item_span, &format!("`{}` should be clean but is not", dep_node_str));
+                .emit_err(errors::NotClean { span: item_span, dep_node_str: &dep_node_str });
         }
     }
 
@@ -370,10 +362,9 @@ impl<'tcx> DirtyCleanVisitor<'tcx> {
 
         if !self.tcx.dep_graph.debug_was_loaded_from_disk(dep_node) {
             let dep_node_str = self.dep_node_str(&dep_node);
-            self.tcx.sess.span_err(
-                item_span,
-                &format!("`{}` should have been loaded from disk but it was not", dep_node_str),
-            );
+            self.tcx
+                .sess
+                .emit_err(errors::NotLoaded { span: item_span, dep_node_str: &dep_node_str });
         }
     }
 
@@ -414,12 +405,12 @@ fn check_config(tcx: TyCtxt<'_>, attr: &Attribute) -> bool {
             debug!("check_config: searching for cfg {:?}", value);
             cfg = Some(config.contains(&(value, None)));
         } else if !(item.has_name(EXCEPT) || item.has_name(LOADED_FROM_DISK)) {
-            tcx.sess.span_err(attr.span, &format!("unknown item `{}`", item.name_or_empty()));
+            tcx.sess.emit_err(errors::UnknownItem { span: attr.span, name: item.name_or_empty() });
         }
     }
 
     match cfg {
-        None => tcx.sess.span_fatal(attr.span, "no cfg attribute"),
+        None => tcx.sess.emit_fatal(errors::NoCfg { span: attr.span }),
         Some(c) => c,
     }
 }
@@ -428,13 +419,11 @@ fn expect_associated_value(tcx: TyCtxt<'_>, item: &NestedMetaItem) -> Symbol {
     if let Some(value) = item.value_str() {
         value
     } else {
-        let msg = if let Some(ident) = item.ident() {
-            format!("associated value expected for `{}`", ident)
+        if let Some(ident) = item.ident() {
+            tcx.sess.emit_fatal(errors::AssociatedValueExpectedFor { span: item.span(), ident });
         } else {
-            "expected an associated value".to_string()
-        };
-
-        tcx.sess.span_fatal(item.span(), &msg);
+            tcx.sess.emit_fatal(errors::AssociatedValueExpected { span: item.span() });
+        }
     }
 }
 
@@ -458,7 +447,7 @@ impl<'tcx> FindAllAttrs<'tcx> {
     fn report_unchecked_attrs(&self, mut checked_attrs: FxHashSet<ast::AttrId>) {
         for attr in &self.found_attrs {
             if !checked_attrs.contains(&attr.id) {
-                self.tcx.sess.span_err(attr.span, "found unchecked `#[rustc_clean]` attribute");
+                self.tcx.sess.emit_err(errors::UncheckedClean { span: attr.span });
                 checked_attrs.insert(attr.id);
             }
         }
diff --git a/compiler/rustc_incremental/src/persist/file_format.rs b/compiler/rustc_incremental/src/persist/file_format.rs
index 2dbd4b6bce85a..dc981c6179eeb 100644
--- a/compiler/rustc_incremental/src/persist/file_format.rs
+++ b/compiler/rustc_incremental/src/persist/file_format.rs
@@ -9,15 +9,15 @@
 //! compiler versions don't change frequently for the typical user, being
 //! conservative here practically has no downside.
 
-use std::env;
-use std::fs;
-use std::io::{self, Read};
-use std::path::{Path, PathBuf};
-
+use crate::errors;
 use rustc_data_structures::memmap::Mmap;
 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use rustc_serialize::Encoder;
 use rustc_session::Session;
+use std::env;
+use std::fs;
+use std::io::{self, Read};
+use std::path::{Path, PathBuf};
 
 /// The first few bytes of files generated by incremental compilation.
 const FILE_MAGIC: &[u8] = b"RSIC";
@@ -60,12 +60,7 @@ where
         }
         Err(err) if err.kind() == io::ErrorKind::NotFound => (),
         Err(err) => {
-            sess.err(&format!(
-                "unable to delete old {} at `{}`: {}",
-                name,
-                path_buf.display(),
-                err
-            ));
+            sess.emit_err(errors::DeleteOld { name, path: path_buf, err });
             return;
         }
     }
@@ -73,7 +68,7 @@ where
     let mut encoder = match FileEncoder::new(&path_buf) {
         Ok(encoder) => encoder,
         Err(err) => {
-            sess.err(&format!("failed to create {} at `{}`: {}", name, path_buf.display(), err));
+            sess.emit_err(errors::CreateNew { name, path: path_buf, err });
             return;
         }
     };
@@ -90,7 +85,7 @@ where
             debug!("save: data written to disk successfully");
         }
         Err(err) => {
-            sess.err(&format!("failed to write {} to `{}`: {}", name, path_buf.display(), err));
+            sess.emit_err(errors::WriteNew { name, path: path_buf, err });
         }
     }
 }
diff --git a/compiler/rustc_incremental/src/persist/fs.rs b/compiler/rustc_incremental/src/persist/fs.rs
index 25c1b2e1c4387..b7fe3263adc9f 100644
--- a/compiler/rustc_incremental/src/persist/fs.rs
+++ b/compiler/rustc_incremental/src/persist/fs.rs
@@ -103,6 +103,7 @@
 //! unsupported file system and emit a warning in that case. This is not yet
 //! implemented.
 
+use crate::errors;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::{base_n, flock};
@@ -225,12 +226,7 @@ pub fn prepare_session_directory(
     let crate_dir = match crate_dir.canonicalize() {
         Ok(v) => v,
         Err(err) => {
-            let reported = sess.err(&format!(
-                "incremental compilation: error canonicalizing path `{}`: {}",
-                crate_dir.display(),
-                err
-            ));
-            return Err(reported);
+            return Err(sess.emit_err(errors::CanonicalizePath { path: crate_dir, err }));
         }
     };
 
@@ -273,14 +269,7 @@ pub fn prepare_session_directory(
             debug!("successfully copied data from: {}", source_directory.display());
 
             if !allows_links {
-                sess.warn(&format!(
-                    "Hard linking files in the incremental \
-                                        compilation cache failed. Copying files \
-                                        instead. Consider moving the cache \
-                                        directory to a file system which supports \
-                                        hard linking in session dir `{}`",
-                    session_dir.display()
-                ));
+                sess.emit_warning(errors::HardLinkFailed { path: &session_dir });
             }
 
             sess.init_incr_comp_session(session_dir, directory_lock, true);
@@ -295,12 +284,7 @@ pub fn prepare_session_directory(
             // Try to remove the session directory we just allocated. We don't
             // know if there's any garbage in it from the failed copy action.
             if let Err(err) = safe_remove_dir_all(&session_dir) {
-                sess.warn(&format!(
-                    "Failed to delete partly initialized \
-                                    session dir `{}`: {}",
-                    session_dir.display(),
-                    err
-                ));
+                sess.emit_warning(errors::DeletePartial { path: &session_dir, err });
             }
 
             delete_session_dir_lock_file(sess, &lock_file_path);
@@ -332,12 +316,7 @@ pub fn finalize_session_directory(sess: &Session, svh: Svh) {
         );
 
         if let Err(err) = safe_remove_dir_all(&*incr_comp_session_dir) {
-            sess.warn(&format!(
-                "Error deleting incremental compilation \
-                                session directory `{}`: {}",
-                incr_comp_session_dir.display(),
-                err
-            ));
+            sess.emit_warning(errors::DeleteFull { path: &incr_comp_session_dir, err });
         }
 
         let lock_file_path = lock_file_path(&*incr_comp_session_dir);
@@ -380,12 +359,7 @@ pub fn finalize_session_directory(sess: &Session, svh: Svh) {
         }
         Err(e) => {
             // Warn about the error. However, no need to abort compilation now.
-            sess.warn(&format!(
-                "Error finalizing incremental compilation \
-                               session directory `{}`: {}",
-                incr_comp_session_dir.display(),
-                e
-            ));
+            sess.emit_warning(errors::Finalize { path: &incr_comp_session_dir, err: e });
 
             debug!("finalize_session_directory() - error, marking as invalid");
             // Drop the file lock, so we can garage collect
@@ -488,16 +462,7 @@ fn create_dir(sess: &Session, path: &Path, dir_tag: &str) -> Result<(), ErrorGua
             debug!("{} directory created successfully", dir_tag);
             Ok(())
         }
-        Err(err) => {
-            let reported = sess.err(&format!(
-                "Could not create incremental compilation {} \
-                               directory `{}`: {}",
-                dir_tag,
-                path.display(),
-                err
-            ));
-            Err(reported)
-        }
+        Err(err) => Err(sess.emit_err(errors::CreateIncrCompDir { tag: dir_tag, path, err })),
     }
 }
 
@@ -518,46 +483,20 @@ fn lock_directory(
         // the lock should be exclusive
         Ok(lock) => Ok((lock, lock_file_path)),
         Err(lock_err) => {
-            let mut err = sess.struct_err(&format!(
-                "incremental compilation: could not create \
-                 session directory lock file: {}",
-                lock_err
-            ));
-            if flock::Lock::error_unsupported(&lock_err) {
-                err.note(&format!(
-                    "the filesystem for the incremental path at {} \
-                     does not appear to support locking, consider changing the \
-                     incremental path to a filesystem that supports locking \
-                     or disable incremental compilation",
-                    session_dir.display()
-                ));
-                if std::env::var_os("CARGO").is_some() {
-                    err.help(
-                        "incremental compilation can be disabled by setting the \
-                         environment variable CARGO_INCREMENTAL=0 (see \
-                         https://doc.rust-lang.org/cargo/reference/profiles.html#incremental)",
-                    );
-                    err.help(
-                        "the entire build directory can be changed to a different \
-                        filesystem by setting the environment variable CARGO_TARGET_DIR \
-                        to a different path (see \
-                        https://doc.rust-lang.org/cargo/reference/config.html#buildtarget-dir)",
-                    );
-                }
-            }
-            Err(err.emit())
+            let is_unsupported_lock = flock::Lock::error_unsupported(&lock_err).then_some(());
+            Err(sess.emit_err(errors::CreateLock {
+                lock_err,
+                session_dir,
+                is_unsupported_lock,
+                is_cargo: std::env::var_os("CARGO").map(|_| ()),
+            }))
         }
     }
 }
 
 fn delete_session_dir_lock_file(sess: &Session, lock_file_path: &Path) {
     if let Err(err) = safe_remove_file(&lock_file_path) {
-        sess.warn(&format!(
-            "Error deleting lock file for incremental \
-                            compilation session directory `{}`: {}",
-            lock_file_path.display(),
-            err
-        ));
+        sess.emit_warning(errors::DeleteLock { path: lock_file_path, err });
     }
 }
 
@@ -774,12 +713,7 @@ pub fn garbage_collect_session_directories(sess: &Session) -> io::Result<()> {
         if !lock_file_to_session_dir.values().any(|dir| *dir == directory_name) {
             let path = crate_directory.join(directory_name);
             if let Err(err) = safe_remove_dir_all(&path) {
-                sess.warn(&format!(
-                    "Failed to garbage collect invalid incremental \
-                                    compilation session directory `{}`: {}",
-                    path.display(),
-                    err
-                ));
+                sess.emit_warning(errors::InvalidGcFailed { path: &path, err });
             }
         }
     }
@@ -885,12 +819,7 @@ pub fn garbage_collect_session_directories(sess: &Session) -> io::Result<()> {
         debug!("garbage_collect_session_directories() - deleting `{}`", path.display());
 
         if let Err(err) = safe_remove_dir_all(&path) {
-            sess.warn(&format!(
-                "Failed to garbage collect finalized incremental \
-                                compilation session directory `{}`: {}",
-                path.display(),
-                err
-            ));
+            sess.emit_warning(errors::FinalizedGcFailed { path: &path, err });
         } else {
             delete_session_dir_lock_file(sess, &lock_file_path(&path));
         }
@@ -907,11 +836,7 @@ fn delete_old(sess: &Session, path: &Path) {
     debug!("garbage_collect_session_directories() - deleting `{}`", path.display());
 
     if let Err(err) = safe_remove_dir_all(&path) {
-        sess.warn(&format!(
-            "Failed to garbage collect incremental compilation session directory `{}`: {}",
-            path.display(),
-            err
-        ));
+        sess.emit_warning(errors::SessionGcFailed { path: &path, err });
     } else {
         delete_session_dir_lock_file(sess, &lock_file_path(&path));
     }
diff --git a/compiler/rustc_incremental/src/persist/load.rs b/compiler/rustc_incremental/src/persist/load.rs
index 1c5fd91690230..d5097065dda2e 100644
--- a/compiler/rustc_incremental/src/persist/load.rs
+++ b/compiler/rustc_incremental/src/persist/load.rs
@@ -1,5 +1,6 @@
 //! Code to save/load the dep-graph from files.
 
+use crate::errors;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::memmap::Mmap;
 use rustc_middle::dep_graph::{SerializedDepGraph, WorkProduct, WorkProductId};
@@ -8,7 +9,7 @@ use rustc_serialize::opaque::MemDecoder;
 use rustc_serialize::Decodable;
 use rustc_session::config::IncrementalStateAssertion;
 use rustc_session::Session;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use super::data::*;
 use super::file_format;
@@ -27,11 +28,10 @@ pub enum LoadResult<T> {
     },
     /// The file either didn't exist or was produced by an incompatible compiler version.
     DataOutOfDate,
-    /// An error occurred.
-    Error {
-        #[allow(missing_docs)]
-        message: String,
-    },
+    /// Loading the dep graph failed.
+    LoadDepGraph(PathBuf, std::io::Error),
+    /// Decoding loaded incremental cache failed.
+    DecodeIncrCache(Box<dyn std::any::Any + Send>),
 }
 
 impl<T: Default> LoadResult<T> {
@@ -40,36 +40,31 @@ impl<T: Default> LoadResult<T> {
         // Check for errors when using `-Zassert-incremental-state`
         match (sess.opts.assert_incr_state, &self) {
             (Some(IncrementalStateAssertion::NotLoaded), LoadResult::Ok { .. }) => {
-                sess.fatal(
-                    "We asserted that the incremental cache should not be loaded, \
-                         but it was loaded.",
-                );
+                sess.emit_fatal(errors::AssertNotLoaded);
             }
             (
                 Some(IncrementalStateAssertion::Loaded),
-                LoadResult::Error { .. } | LoadResult::DataOutOfDate,
+                LoadResult::LoadDepGraph(..)
+                | LoadResult::DecodeIncrCache(..)
+                | LoadResult::DataOutOfDate,
             ) => {
-                sess.fatal(
-                    "We asserted that an existing incremental cache directory should \
-                         be successfully loaded, but it was not.",
-                );
+                sess.emit_fatal(errors::AssertLoaded);
             }
             _ => {}
         };
 
         match self {
-            LoadResult::Error { message } => {
-                sess.warn(&message);
+            LoadResult::LoadDepGraph(path, err) => {
+                sess.emit_warning(errors::LoadDepGraph { path, err });
+                Default::default()
+            }
+            LoadResult::DecodeIncrCache(err) => {
+                sess.emit_warning(errors::DecodeIncrCache { err: format!("{err:?}") });
                 Default::default()
             }
             LoadResult::DataOutOfDate => {
                 if let Err(err) = delete_all_session_dir_contents(sess) {
-                    sess.err(&format!(
-                        "Failed to delete invalidated or incompatible \
-                         incremental compilation session directory contents `{}`: {}.",
-                        dep_graph_path(sess).display(),
-                        err
-                    ));
+                    sess.emit_err(errors::DeleteIncompatible { path: dep_graph_path(sess), err });
                 }
                 Default::default()
             }
@@ -90,9 +85,7 @@ fn load_data(
             // compiler version. Neither is an error.
             LoadResult::DataOutOfDate
         }
-        Err(err) => LoadResult::Error {
-            message: format!("could not load dep-graph from `{}`: {}", path.display(), err),
-        },
+        Err(err) => LoadResult::LoadDepGraph(path.to_path_buf(), err),
     }
 }
 
@@ -114,9 +107,9 @@ impl<T> MaybeAsync<LoadResult<T>> {
     pub fn open(self) -> LoadResult<T> {
         match self {
             MaybeAsync::Sync(result) => result,
-            MaybeAsync::Async(handle) => handle.join().unwrap_or_else(|e| LoadResult::Error {
-                message: format!("could not decode incremental cache: {:?}", e),
-            }),
+            MaybeAsync::Async(handle) => {
+                handle.join().unwrap_or_else(|e| LoadResult::DecodeIncrCache(e))
+            }
         }
     }
 }
@@ -185,7 +178,8 @@ pub fn load_dep_graph(sess: &Session) -> DepGraphFuture {
 
         match load_data(report_incremental_info, &path, nightly_build) {
             LoadResult::DataOutOfDate => LoadResult::DataOutOfDate,
-            LoadResult::Error { message } => LoadResult::Error { message },
+            LoadResult::LoadDepGraph(path, err) => LoadResult::LoadDepGraph(path, err),
+            LoadResult::DecodeIncrCache(err) => LoadResult::DecodeIncrCache(err),
             LoadResult::Ok { data: (bytes, start_pos) } => {
                 let mut decoder = MemDecoder::new(&bytes, start_pos);
                 let prev_commandline_args_hash = u64::decode(&mut decoder);
diff --git a/compiler/rustc_incremental/src/persist/save.rs b/compiler/rustc_incremental/src/persist/save.rs
index 710350314975c..7731351a80b7c 100644
--- a/compiler/rustc_incremental/src/persist/save.rs
+++ b/compiler/rustc_incremental/src/persist/save.rs
@@ -1,3 +1,4 @@
+use crate::errors;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::join;
 use rustc_middle::dep_graph::{DepGraph, SerializedDepGraph, WorkProduct, WorkProductId};
@@ -59,19 +60,14 @@ pub fn save_dep_graph(tcx: TyCtxt<'_>) {
             move || {
                 sess.time("incr_comp_persist_dep_graph", || {
                     if let Err(err) = tcx.dep_graph.encode(&tcx.sess.prof) {
-                        sess.err(&format!(
-                            "failed to write dependency graph to `{}`: {}",
-                            staging_dep_graph_path.display(),
-                            err
-                        ));
+                        sess.emit_err(errors::WriteDepGraph { path: &staging_dep_graph_path, err });
                     }
                     if let Err(err) = fs::rename(&staging_dep_graph_path, &dep_graph_path) {
-                        sess.err(&format!(
-                            "failed to move dependency graph from `{}` to `{}`: {}",
-                            staging_dep_graph_path.display(),
-                            dep_graph_path.display(),
-                            err
-                        ));
+                        sess.emit_err(errors::MoveDepGraph {
+                            from: &staging_dep_graph_path,
+                            to: &dep_graph_path,
+                            err,
+                        });
                     }
                 });
             },
@@ -163,11 +159,7 @@ pub fn build_dep_graph(
     let mut encoder = match FileEncoder::new(&path_buf) {
         Ok(encoder) => encoder,
         Err(err) => {
-            sess.err(&format!(
-                "failed to create dependency graph at `{}`: {}",
-                path_buf.display(),
-                err
-            ));
+            sess.emit_err(errors::CreateDepGraph { path: &path_buf, err });
             return None;
         }
     };
diff --git a/compiler/rustc_incremental/src/persist/work_product.rs b/compiler/rustc_incremental/src/persist/work_product.rs
index 2f1853c441eee..dc98fbeb0d166 100644
--- a/compiler/rustc_incremental/src/persist/work_product.rs
+++ b/compiler/rustc_incremental/src/persist/work_product.rs
@@ -2,6 +2,7 @@
 //!
 //! [work products]: WorkProduct
 
+use crate::errors;
 use crate::persist::fs::*;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_fs_util::link_or_copy;
@@ -28,12 +29,11 @@ pub fn copy_cgu_workproduct_to_incr_comp_cache_dir(
                 let _ = saved_files.insert(ext.to_string(), file_name);
             }
             Err(err) => {
-                sess.warn(&format!(
-                    "error copying object file `{}` to incremental directory as `{}`: {}",
-                    path.display(),
-                    path_in_incr_dir.display(),
-                    err
-                ));
+                sess.emit_warning(errors::CopyWorkProductToCache {
+                    from: &path,
+                    to: &path_in_incr_dir,
+                    err,
+                });
             }
         }
     }
@@ -49,11 +49,7 @@ pub fn delete_workproduct_files(sess: &Session, work_product: &WorkProduct) {
     for (_, path) in &work_product.saved_files {
         let path = in_incr_comp_dir_sess(sess, path);
         if let Err(err) = std_fs::remove_file(&path) {
-            sess.warn(&format!(
-                "file-system error deleting outdated file `{}`: {}",
-                path.display(),
-                err
-            ));
+            sess.emit_warning(errors::DeleteWorkProduct { path: &path, err });
         }
     }
 }
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 95e34da734d6a..2dca6acdd6d6f 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -3094,7 +3094,7 @@ declare_lint! {
     ///
     /// ### Example
     ///
-    /// ```rust
+    /// ```rust,compile_fail
     /// #![cfg_attr(debug_assertions, crate_type = "lib")]
     /// ```
     ///
@@ -3114,7 +3114,7 @@ declare_lint! {
     /// rustc instead of `#![cfg_attr(..., crate_type = "...")]` and
     /// `--crate-name` instead of `#![cfg_attr(..., crate_name = "...")]`.
     pub DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
-    Warn,
+    Deny,
     "detects usage of `#![cfg_attr(..., crate_type/crate_name = \"...\")]`",
     @future_incompatible = FutureIncompatibleInfo {
         reference: "issue #91632 <https://github.com/rust-lang/rust/issues/91632>",
diff --git a/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs b/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
index edf4dbed9853e..6bd5fee443e26 100644
--- a/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
+++ b/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
@@ -12,7 +12,7 @@ use quote::{format_ident, quote};
 use std::collections::HashMap;
 use std::fmt;
 use std::str::FromStr;
-use syn::{parse_quote, spanned::Spanned, Meta, MetaList, MetaNameValue, NestedMeta, Path};
+use syn::{spanned::Spanned, Attribute, Meta, MetaList, MetaNameValue, NestedMeta, Path};
 use synstructure::{BindingInfo, Structure, VariantInfo};
 
 /// Which kind of suggestion is being created?
@@ -28,8 +28,41 @@ enum SubdiagnosticSuggestionKind {
     Verbose,
 }
 
+impl FromStr for SubdiagnosticSuggestionKind {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "" => Ok(SubdiagnosticSuggestionKind::Normal),
+            "_short" => Ok(SubdiagnosticSuggestionKind::Short),
+            "_hidden" => Ok(SubdiagnosticSuggestionKind::Hidden),
+            "_verbose" => Ok(SubdiagnosticSuggestionKind::Verbose),
+            _ => Err(()),
+        }
+    }
+}
+
+impl SubdiagnosticSuggestionKind {
+    pub fn to_suggestion_style(&self) -> TokenStream {
+        match self {
+            SubdiagnosticSuggestionKind::Normal => {
+                quote! { rustc_errors::SuggestionStyle::ShowCode }
+            }
+            SubdiagnosticSuggestionKind::Short => {
+                quote! { rustc_errors::SuggestionStyle::HideCodeInline }
+            }
+            SubdiagnosticSuggestionKind::Hidden => {
+                quote! { rustc_errors::SuggestionStyle::HideCodeAlways }
+            }
+            SubdiagnosticSuggestionKind::Verbose => {
+                quote! { rustc_errors::SuggestionStyle::ShowAlways }
+            }
+        }
+    }
+}
+
 /// Which kind of subdiagnostic is being created from a variant?
-#[derive(Clone, Copy)]
+#[derive(Clone)]
 enum SubdiagnosticKind {
     /// `#[label(...)]`
     Label,
@@ -40,31 +73,9 @@ enum SubdiagnosticKind {
     /// `#[warn_(...)]`
     Warn,
     /// `#[suggestion{,_short,_hidden,_verbose}]`
-    Suggestion(SubdiagnosticSuggestionKind),
-}
-
-impl FromStr for SubdiagnosticKind {
-    type Err = ();
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        match s {
-            "label" => Ok(SubdiagnosticKind::Label),
-            "note" => Ok(SubdiagnosticKind::Note),
-            "help" => Ok(SubdiagnosticKind::Help),
-            "warn_" => Ok(SubdiagnosticKind::Warn),
-            "suggestion" => Ok(SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Normal)),
-            "suggestion_short" => {
-                Ok(SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Short))
-            }
-            "suggestion_hidden" => {
-                Ok(SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Hidden))
-            }
-            "suggestion_verbose" => {
-                Ok(SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Verbose))
-            }
-            _ => Err(()),
-        }
-    }
+    Suggestion { suggestion_kind: SubdiagnosticSuggestionKind, code: TokenStream },
+    /// `#[multipart_suggestion{,_short,_hidden,_verbose}]`
+    MultipartSuggestion { suggestion_kind: SubdiagnosticSuggestionKind },
 }
 
 impl quote::IdentFragment for SubdiagnosticKind {
@@ -74,17 +85,9 @@ impl quote::IdentFragment for SubdiagnosticKind {
             SubdiagnosticKind::Note => write!(f, "note"),
             SubdiagnosticKind::Help => write!(f, "help"),
             SubdiagnosticKind::Warn => write!(f, "warn"),
-            SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Normal) => {
-                write!(f, "suggestion")
-            }
-            SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Short) => {
-                write!(f, "suggestion_short")
-            }
-            SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Hidden) => {
-                write!(f, "suggestion_hidden")
-            }
-            SubdiagnosticKind::Suggestion(SubdiagnosticSuggestionKind::Verbose) => {
-                write!(f, "suggestion_verbose")
+            SubdiagnosticKind::Suggestion { .. } => write!(f, "suggestion_with_style"),
+            SubdiagnosticKind::MultipartSuggestion { .. } => {
+                write!(f, "multipart_suggestion_with_style")
             }
         }
     }
@@ -148,11 +151,9 @@ impl<'a> SessionSubdiagnosticDerive<'a> {
                     variant,
                     span,
                     fields: fields_map,
-                    kind: None,
-                    slug: None,
-                    code: None,
                     span_field: None,
                     applicability: None,
+                    has_suggestion_parts: false,
                 };
                 builder.into_tokens().unwrap_or_else(|v| v.to_compile_error())
             });
@@ -193,21 +194,15 @@ struct SessionSubdiagnosticDeriveBuilder<'a> {
     /// derive builder.
     fields: HashMap<String, TokenStream>,
 
-    /// Subdiagnostic kind of the type/variant.
-    kind: Option<(SubdiagnosticKind, proc_macro::Span)>,
-
-    /// Slug of the subdiagnostic - corresponds to the Fluent identifier for the message - from the
-    /// `#[kind(slug)]` attribute on the type or variant.
-    slug: Option<(Path, proc_macro::Span)>,
-    /// If a suggestion, the code to suggest as a replacement - from the `#[kind(code = "...")]`
-    /// attribute on the type or variant.
-    code: Option<(TokenStream, proc_macro::Span)>,
-
     /// Identifier for the binding to the `#[primary_span]` field.
     span_field: Option<(proc_macro2::Ident, proc_macro::Span)>,
     /// If a suggestion, the identifier for the binding to the `#[applicability]` field or a
     /// `rustc_errors::Applicability::*` variant directly.
     applicability: Option<(TokenStream, proc_macro::Span)>,
+
+    /// Set to true when a `#[suggestion_part]` field is encountered, used to generate an error
+    /// during finalization if still `false`.
+    has_suggestion_parts: bool,
 }
 
 impl<'a> HasFieldMap for SessionSubdiagnosticDeriveBuilder<'a> {
@@ -217,7 +212,11 @@ impl<'a> HasFieldMap for SessionSubdiagnosticDeriveBuilder<'a> {
 }
 
 impl<'a> SessionSubdiagnosticDeriveBuilder<'a> {
-    fn identify_kind(&mut self) -> Result<(), DiagnosticDeriveError> {
+    fn identify_kind(
+        &mut self,
+    ) -> Result<Option<(SubdiagnosticKind, Path)>, DiagnosticDeriveError> {
+        let mut kind_slug = None;
+
         for attr in self.variant.ast().attrs {
             let span = attr.span().unwrap();
 
@@ -225,116 +224,121 @@ impl<'a> SessionSubdiagnosticDeriveBuilder<'a> {
             let name = name.as_str();
 
             let meta = attr.parse_meta()?;
-            let kind = match meta {
-                Meta::List(MetaList { ref nested, .. }) => {
-                    let mut nested_iter = nested.into_iter();
-                    if let Some(nested_attr) = nested_iter.next() {
-                        match nested_attr {
-                            NestedMeta::Meta(Meta::Path(path)) => {
-                                self.slug.set_once((path.clone(), span));
-                            }
-                            NestedMeta::Meta(meta @ Meta::NameValue(_))
-                                if matches!(
-                                    meta.path().segments.last().unwrap().ident.to_string().as_str(),
-                                    "code" | "applicability"
-                                ) =>
-                            {
-                                // don't error for valid follow-up attributes
-                            }
-                            nested_attr => {
-                                throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
-                                    diag.help(
-                                        "first argument of the attribute should be the diagnostic \
-                                         slug",
-                                    )
-                                })
-                            }
-                        };
-                    }
+            let Meta::List(MetaList { ref nested, .. }) = meta else {
+                throw_invalid_attr!(attr, &meta);
+            };
 
-                    for nested_attr in nested_iter {
-                        let meta = match nested_attr {
-                            NestedMeta::Meta(ref meta) => meta,
-                            _ => throw_invalid_nested_attr!(attr, &nested_attr),
-                        };
-
-                        let span = meta.span().unwrap();
-                        let nested_name = meta.path().segments.last().unwrap().ident.to_string();
-                        let nested_name = nested_name.as_str();
-
-                        match meta {
-                            Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => {
-                                match nested_name {
-                                    "code" => {
-                                        let formatted_str = self.build_format(&s.value(), s.span());
-                                        self.code.set_once((formatted_str, span));
-                                    }
-                                    "applicability" => {
-                                        let value = match Applicability::from_str(&s.value()) {
-                                            Ok(v) => v,
-                                            Err(()) => {
-                                                span_err(span, "invalid applicability").emit();
-                                                Applicability::Unspecified
-                                            }
-                                        };
-                                        self.applicability.set_once((quote! { #value }, span));
-                                    }
-                                    _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
-                                        diag.help(
-                                            "only `code` and `applicability` are valid nested \
-                                             attributes",
-                                        )
-                                    }),
-                                }
-                            }
-                            _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
-                                if matches!(meta, Meta::Path(_)) {
-                                    diag.help(
-                                        "a diagnostic slug must be the first argument to the \
-                                         attribute",
-                                    )
-                                } else {
-                                    diag
-                                }
-                            }),
-                        }
+            let mut kind = match name {
+                "label" => SubdiagnosticKind::Label,
+                "note" => SubdiagnosticKind::Note,
+                "help" => SubdiagnosticKind::Help,
+                "warn_" => SubdiagnosticKind::Warn,
+                _ => {
+                    if let Some(suggestion_kind) =
+                        name.strip_prefix("suggestion").and_then(|s| s.parse().ok())
+                    {
+                        SubdiagnosticKind::Suggestion { suggestion_kind, code: TokenStream::new() }
+                    } else if let Some(suggestion_kind) =
+                        name.strip_prefix("multipart_suggestion").and_then(|s| s.parse().ok())
+                    {
+                        SubdiagnosticKind::MultipartSuggestion { suggestion_kind }
+                    } else {
+                        throw_invalid_attr!(attr, &meta);
                     }
-
-                    let Ok(kind) = SubdiagnosticKind::from_str(name) else {
-                        throw_invalid_attr!(attr, &meta)
-                    };
-
-                    kind
                 }
-                _ => throw_invalid_attr!(attr, &meta),
             };
 
-            if matches!(
-                kind,
-                SubdiagnosticKind::Label | SubdiagnosticKind::Help | SubdiagnosticKind::Note
-            ) && self.code.is_some()
-            {
-                throw_span_err!(
-                    span,
-                    &format!("`code` is not a valid nested attribute of a `{}` attribute", name)
-                );
+            let mut slug = None;
+            let mut code = None;
+
+            let mut nested_iter = nested.into_iter();
+            if let Some(nested_attr) = nested_iter.next() {
+                match nested_attr {
+                    NestedMeta::Meta(Meta::Path(path)) => {
+                        slug.set_once((path.clone(), span));
+                    }
+                    NestedMeta::Meta(meta @ Meta::NameValue(_))
+                        if matches!(
+                            meta.path().segments.last().unwrap().ident.to_string().as_str(),
+                            "code" | "applicability"
+                        ) =>
+                    {
+                        // Don't error for valid follow-up attributes.
+                    }
+                    nested_attr => {
+                        throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                            diag.help(
+                                "first argument of the attribute should be the diagnostic \
+                                 slug",
+                            )
+                        })
+                    }
+                };
             }
 
-            if matches!(
-                kind,
-                SubdiagnosticKind::Label | SubdiagnosticKind::Help | SubdiagnosticKind::Note
-            ) && self.applicability.is_some()
-            {
-                throw_span_err!(
-                    span,
-                    &format!(
-                        "`applicability` is not a valid nested attribute of a `{}` attribute",
-                        name
-                    )
-                );
+            for nested_attr in nested_iter {
+                let meta = match nested_attr {
+                    NestedMeta::Meta(ref meta) => meta,
+                    _ => throw_invalid_nested_attr!(attr, &nested_attr),
+                };
+
+                let span = meta.span().unwrap();
+                let nested_name = meta.path().segments.last().unwrap().ident.to_string();
+                let nested_name = nested_name.as_str();
+
+                let value = match meta {
+                    Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(value), .. }) => value,
+                    Meta::Path(_) => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                        diag.help("a diagnostic slug must be the first argument to the attribute")
+                    }),
+                    _ => throw_invalid_nested_attr!(attr, &nested_attr),
+                };
+
+                match nested_name {
+                    "code" => {
+                        if matches!(kind, SubdiagnosticKind::Suggestion { .. }) {
+                            let formatted_str = self.build_format(&value.value(), value.span());
+                            code.set_once((formatted_str, span));
+                        } else {
+                            span_err(
+                                span,
+                                &format!(
+                                    "`code` is not a valid nested attribute of a `{}` attribute",
+                                    name
+                                ),
+                            )
+                            .emit();
+                        }
+                    }
+                    "applicability" => {
+                        if matches!(
+                            kind,
+                            SubdiagnosticKind::Suggestion { .. }
+                                | SubdiagnosticKind::MultipartSuggestion { .. }
+                        ) {
+                            let value =
+                                Applicability::from_str(&value.value()).unwrap_or_else(|()| {
+                                    span_err(span, "invalid applicability").emit();
+                                    Applicability::Unspecified
+                                });
+                            self.applicability.set_once((quote! { #value }, span));
+                        } else {
+                            span_err(
+                                span,
+                                &format!(
+                                    "`applicability` is not a valid nested attribute of a `{}` attribute",
+                                    name
+                                )
+                            ).emit();
+                        }
+                    }
+                    _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                        diag.help("only `code` and `applicability` are valid nested attributes")
+                    }),
+                }
             }
 
-            if self.slug.is_none() {
+            let Some((slug, _)) = slug else {
                 throw_span_err!(
                     span,
                     &format!(
@@ -342,150 +346,338 @@ impl<'a> SessionSubdiagnosticDeriveBuilder<'a> {
                         name
                     )
                 );
+            };
+
+            match kind {
+                SubdiagnosticKind::Suggestion { code: ref mut code_field, .. } => {
+                    let Some((code, _)) = code else {
+                        throw_span_err!(span, "suggestion without `code = \"...\"`");
+                    };
+                    *code_field = code;
+                }
+                SubdiagnosticKind::Label
+                | SubdiagnosticKind::Note
+                | SubdiagnosticKind::Help
+                | SubdiagnosticKind::Warn
+                | SubdiagnosticKind::MultipartSuggestion { .. } => {}
             }
 
-            self.kind.set_once((kind, span));
+            kind_slug.set_once(((kind, slug), span))
         }
 
-        Ok(())
+        Ok(kind_slug.map(|(kind_slug, _)| kind_slug))
+    }
+
+    /// Generates the code for a field with no attributes.
+    fn generate_field_set_arg(&mut self, binding: &BindingInfo<'_>) -> TokenStream {
+        let ast = binding.ast();
+        assert_eq!(ast.attrs.len(), 0, "field with attribute used as diagnostic arg");
+
+        let diag = &self.diag;
+        let ident = ast.ident.as_ref().unwrap();
+        quote! {
+            #diag.set_arg(
+                stringify!(#ident),
+                #binding
+            );
+        }
     }
 
-    fn generate_field_code(
+    /// Generates the necessary code for all attributes on a field.
+    fn generate_field_attr_code(
         &mut self,
         binding: &BindingInfo<'_>,
-        is_suggestion: bool,
-    ) -> Result<TokenStream, DiagnosticDeriveError> {
+        kind: &SubdiagnosticKind,
+    ) -> TokenStream {
         let ast = binding.ast();
+        assert!(ast.attrs.len() > 0, "field without attributes generating attr code");
 
+        // Abstract over `Vec<T>` and `Option<T>` fields using `FieldInnerTy`, which will
+        // apply the generated code on each element in the `Vec` or `Option`.
         let inner_ty = FieldInnerTy::from_type(&ast.ty);
-        let info = FieldInfo {
-            binding: binding,
-            ty: inner_ty.inner_type().unwrap_or(&ast.ty),
-            span: &ast.span(),
-        };
+        ast.attrs
+            .iter()
+            .map(|attr| {
+                let info = FieldInfo {
+                    binding,
+                    ty: inner_ty.inner_type().unwrap_or(&ast.ty),
+                    span: &ast.span(),
+                };
 
-        for attr in &ast.attrs {
-            let name = attr.path.segments.last().unwrap().ident.to_string();
-            let name = name.as_str();
-            let span = attr.span().unwrap();
+                let generated = self
+                    .generate_field_code_inner(kind, attr, info)
+                    .unwrap_or_else(|v| v.to_compile_error());
 
-            let meta = attr.parse_meta()?;
-            match meta {
-                Meta::Path(_) => match name {
-                    "primary_span" => {
-                        report_error_if_not_applied_to_span(attr, &info)?;
-                        self.span_field.set_once((binding.binding.clone(), span));
-                        return Ok(quote! {});
-                    }
-                    "applicability" if is_suggestion => {
-                        report_error_if_not_applied_to_applicability(attr, &info)?;
-                        let binding = binding.binding.clone();
-                        self.applicability.set_once((quote! { #binding }, span));
-                        return Ok(quote! {});
-                    }
-                    "applicability" => {
-                        span_err(span, "`#[applicability]` is only valid on suggestions").emit();
-                        return Ok(quote! {});
-                    }
-                    "skip_arg" => {
-                        return Ok(quote! {});
-                    }
-                    _ => throw_invalid_attr!(attr, &meta, |diag| {
+                inner_ty.with(binding, generated)
+            })
+            .collect()
+    }
+
+    fn generate_field_code_inner(
+        &mut self,
+        kind: &SubdiagnosticKind,
+        attr: &Attribute,
+        info: FieldInfo<'_>,
+    ) -> Result<TokenStream, DiagnosticDeriveError> {
+        let meta = attr.parse_meta()?;
+        match meta {
+            Meta::Path(path) => self.generate_field_code_inner_path(kind, attr, info, path),
+            Meta::List(list @ MetaList { .. }) => {
+                self.generate_field_code_inner_list(kind, attr, info, list)
+            }
+            _ => throw_invalid_attr!(attr, &meta),
+        }
+    }
+
+    /// Generates the code for a `[Meta::Path]`-like attribute on a field (e.g. `#[primary_span]`).
+    fn generate_field_code_inner_path(
+        &mut self,
+        kind: &SubdiagnosticKind,
+        attr: &Attribute,
+        info: FieldInfo<'_>,
+        path: Path,
+    ) -> Result<TokenStream, DiagnosticDeriveError> {
+        let span = attr.span().unwrap();
+        let ident = &path.segments.last().unwrap().ident;
+        let name = ident.to_string();
+        let name = name.as_str();
+
+        match name {
+            "skip_arg" => Ok(quote! {}),
+            "primary_span" => {
+                if matches!(kind, SubdiagnosticKind::MultipartSuggestion { .. }) {
+                    throw_invalid_attr!(attr, &Meta::Path(path), |diag| {
                         diag.help(
-                            "only `primary_span`, `applicability` and `skip_arg` are valid field \
-                             attributes",
+                            "multipart suggestions use one or more `#[suggestion_part]`s rather \
+                            than one `#[primary_span]`",
                         )
-                    }),
-                },
-                _ => throw_invalid_attr!(attr, &meta),
+                    })
+                }
+
+                report_error_if_not_applied_to_span(attr, &info)?;
+
+                let binding = info.binding.binding.clone();
+                self.span_field.set_once((binding, span));
+
+                Ok(quote! {})
             }
+            "suggestion_part" => {
+                self.has_suggestion_parts = true;
+
+                match kind {
+                    SubdiagnosticKind::MultipartSuggestion { .. } => {
+                        span_err(
+                            span,
+                            "`#[suggestion_part(...)]` attribute without `code = \"...\"`",
+                        )
+                        .emit();
+                        Ok(quote! {})
+                    }
+                    SubdiagnosticKind::Label
+                    | SubdiagnosticKind::Note
+                    | SubdiagnosticKind::Help
+                    | SubdiagnosticKind::Warn
+                    | SubdiagnosticKind::Suggestion { .. } => {
+                        throw_invalid_attr!(attr, &Meta::Path(path), |diag| {
+                            diag.help(
+                                "`#[suggestion_part(...)]` is only valid in multipart suggestions, use `#[primary_span]` instead",
+                            )
+                        });
+                    }
+                }
+            }
+            "applicability" => {
+                if let SubdiagnosticKind::Suggestion { .. }
+                | SubdiagnosticKind::MultipartSuggestion { .. } = kind
+                {
+                    report_error_if_not_applied_to_applicability(attr, &info)?;
+
+                    let binding = info.binding.binding.clone();
+                    self.applicability.set_once((quote! { #binding }, span));
+                } else {
+                    span_err(span, "`#[applicability]` is only valid on suggestions").emit();
+                }
+
+                Ok(quote! {})
+            }
+            _ => throw_invalid_attr!(attr, &Meta::Path(path), |diag| {
+                let span_attr = if let SubdiagnosticKind::MultipartSuggestion { .. } = kind {
+                    "suggestion_part"
+                } else {
+                    "primary_span"
+                };
+                diag.help(format!(
+                    "only `{span_attr}`, `applicability` and `skip_arg` are valid field attributes",
+                ))
+            }),
         }
+    }
 
-        let ident = ast.ident.as_ref().unwrap();
+    /// Generates the code for a `[Meta::List]`-like attribute on a field (e.g.
+    /// `#[suggestion_part(code = "...")]`).
+    fn generate_field_code_inner_list(
+        &mut self,
+        kind: &SubdiagnosticKind,
+        attr: &Attribute,
+        info: FieldInfo<'_>,
+        list: MetaList,
+    ) -> Result<TokenStream, DiagnosticDeriveError> {
+        let span = attr.span().unwrap();
+        let ident = &list.path.segments.last().unwrap().ident;
+        let name = ident.to_string();
+        let name = name.as_str();
+
+        match name {
+            "suggestion_part" => {
+                if !matches!(kind, SubdiagnosticKind::MultipartSuggestion { .. }) {
+                    throw_invalid_attr!(attr, &Meta::List(list), |diag| {
+                        diag.help(
+                            "`#[suggestion_part(...)]` is only valid in multipart suggestions",
+                        )
+                    })
+                }
 
-        let diag = &self.diag;
-        let generated = quote! {
-            #diag.set_arg(
-                stringify!(#ident),
-                #binding
-            );
-        };
+                self.has_suggestion_parts = true;
+
+                report_error_if_not_applied_to_span(attr, &info)?;
+
+                let mut code = None;
+                for nested_attr in list.nested.iter() {
+                    let NestedMeta::Meta(ref meta) = nested_attr else {
+                        throw_invalid_nested_attr!(attr, &nested_attr);
+                    };
+
+                    let span = meta.span().unwrap();
+                    let nested_name = meta.path().segments.last().unwrap().ident.to_string();
+                    let nested_name = nested_name.as_str();
+
+                    let Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(value), .. }) = meta else {
+                        throw_invalid_nested_attr!(attr, &nested_attr);
+                    };
+
+                    match nested_name {
+                        "code" => {
+                            let formatted_str = self.build_format(&value.value(), value.span());
+                            code.set_once((formatted_str, span));
+                        }
+                        _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                            diag.help("`code` is the only valid nested attribute")
+                        }),
+                    }
+                }
+
+                let Some((code, _)) = code else {
+                    span_err(span, "`#[suggestion_part(...)]` attribute without `code = \"...\"`")
+                        .emit();
+                    return Ok(quote! {});
+                };
+                let binding = info.binding;
 
-        Ok(inner_ty.with(binding, generated))
+                Ok(quote! { suggestions.push((#binding, #code)); })
+            }
+            _ => throw_invalid_attr!(attr, &Meta::List(list), |diag| {
+                let span_attr = if let SubdiagnosticKind::MultipartSuggestion { .. } = kind {
+                    "suggestion_part"
+                } else {
+                    "primary_span"
+                };
+                diag.help(format!(
+                    "only `{span_attr}`, `applicability` and `skip_arg` are valid field attributes",
+                ))
+            }),
+        }
     }
 
-    fn into_tokens(&mut self) -> Result<TokenStream, DiagnosticDeriveError> {
-        self.identify_kind()?;
-        let Some(kind) = self.kind.map(|(kind, _)| kind) else {
+    pub fn into_tokens(&mut self) -> Result<TokenStream, DiagnosticDeriveError> {
+        let Some((kind, slug)) = self.identify_kind()? else {
             throw_span_err!(
                 self.variant.ast().ident.span().unwrap(),
                 "subdiagnostic kind not specified"
             );
         };
 
-        let is_suggestion = matches!(kind, SubdiagnosticKind::Suggestion(_));
-
-        let mut args = TokenStream::new();
-        for binding in self.variant.bindings() {
-            let arg = self
-                .generate_field_code(binding, is_suggestion)
-                .unwrap_or_else(|v| v.to_compile_error());
-            args.extend(arg);
-        }
-
-        // Missing slug errors will already have been reported.
-        let slug = self
-            .slug
-            .as_ref()
-            .map(|(slug, _)| slug.clone())
-            .unwrap_or_else(|| parse_quote! { you::need::to::specify::a::slug });
-        let code = match self.code.as_ref() {
-            Some((code, _)) => Some(quote! { #code }),
-            None if is_suggestion => {
-                span_err(self.span, "suggestion without `code = \"...\"`").emit();
-                Some(quote! { /* macro error */ "..." })
+        let init = match &kind {
+            SubdiagnosticKind::Label
+            | SubdiagnosticKind::Note
+            | SubdiagnosticKind::Help
+            | SubdiagnosticKind::Warn
+            | SubdiagnosticKind::Suggestion { .. } => quote! {},
+            SubdiagnosticKind::MultipartSuggestion { .. } => {
+                quote! { let mut suggestions = Vec::new(); }
             }
-            None => None,
         };
 
+        let attr_args: TokenStream = self
+            .variant
+            .bindings()
+            .iter()
+            .filter(|binding| !binding.ast().attrs.is_empty())
+            .map(|binding| self.generate_field_attr_code(binding, &kind))
+            .collect();
+
         let span_field = self.span_field.as_ref().map(|(span, _)| span);
-        let applicability = match self.applicability.clone() {
-            Some((applicability, _)) => Some(applicability),
-            None if is_suggestion => {
-                span_err(self.span, "suggestion without `applicability`").emit();
-                Some(quote! { rustc_errors::Applicability::Unspecified })
-            }
-            None => None,
-        };
+        let applicability = self.applicability.take().map_or_else(
+            || quote! { rustc_errors::Applicability::Unspecified },
+            |(applicability, _)| applicability,
+        );
 
         let diag = &self.diag;
         let name = format_ident!("{}{}", if span_field.is_some() { "span_" } else { "" }, kind);
         let message = quote! { rustc_errors::fluent::#slug };
-        let call = if matches!(kind, SubdiagnosticKind::Suggestion(..)) {
-            if let Some(span) = span_field {
-                quote! { #diag.#name(#span, #message, #code, #applicability); }
-            } else {
-                span_err(self.span, "suggestion without `#[primary_span]` field").emit();
-                quote! { unreachable!(); }
+        let call = match kind {
+            SubdiagnosticKind::Suggestion { suggestion_kind, code } => {
+                if let Some(span) = span_field {
+                    let style = suggestion_kind.to_suggestion_style();
+
+                    quote! { #diag.#name(#span, #message, #code, #applicability, #style); }
+                } else {
+                    span_err(self.span, "suggestion without `#[primary_span]` field").emit();
+                    quote! { unreachable!(); }
+                }
             }
-        } else if matches!(kind, SubdiagnosticKind::Label) {
-            if let Some(span) = span_field {
-                quote! { #diag.#name(#span, #message); }
-            } else {
-                span_err(self.span, "label without `#[primary_span]` field").emit();
-                quote! { unreachable!(); }
+            SubdiagnosticKind::MultipartSuggestion { suggestion_kind } => {
+                if !self.has_suggestion_parts {
+                    span_err(
+                        self.span,
+                        "multipart suggestion without any `#[suggestion_part(...)]` fields",
+                    )
+                    .emit();
+                }
+
+                let style = suggestion_kind.to_suggestion_style();
+
+                quote! { #diag.#name(#message, suggestions, #applicability, #style); }
             }
-        } else {
-            if let Some(span) = span_field {
-                quote! { #diag.#name(#span, #message); }
-            } else {
-                quote! { #diag.#name(#message); }
+            SubdiagnosticKind::Label => {
+                if let Some(span) = span_field {
+                    quote! { #diag.#name(#span, #message); }
+                } else {
+                    span_err(self.span, "label without `#[primary_span]` field").emit();
+                    quote! { unreachable!(); }
+                }
+            }
+            _ => {
+                if let Some(span) = span_field {
+                    quote! { #diag.#name(#span, #message); }
+                } else {
+                    quote! { #diag.#name(#message); }
+                }
             }
         };
 
+        let plain_args: TokenStream = self
+            .variant
+            .bindings()
+            .iter()
+            .filter(|binding| binding.ast().attrs.is_empty())
+            .map(|binding| self.generate_field_set_arg(binding))
+            .collect();
+
         Ok(quote! {
+            #init
+            #attr_args
             #call
-            #args
+            #plain_args
         })
     }
 }
diff --git a/compiler/rustc_macros/src/lib.rs b/compiler/rustc_macros/src/lib.rs
index 87d7ab6ed517b..7b254f40db6d2 100644
--- a/compiler/rustc_macros/src/lib.rs
+++ b/compiler/rustc_macros/src/lib.rs
@@ -171,8 +171,13 @@ decl_derive!(
         suggestion_short,
         suggestion_hidden,
         suggestion_verbose,
+        multipart_suggestion,
+        multipart_suggestion_short,
+        multipart_suggestion_hidden,
+        multipart_suggestion_verbose,
         // field attributes
         skip_arg,
         primary_span,
+        suggestion_part,
         applicability)] => diagnostics::session_subdiagnostic_derive
 );
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index ec5e5170d3594..1738a61eb7787 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -528,9 +528,11 @@ impl Session {
             Err(ErrorGuaranteed::unchecked_claim_error_was_emitted())
         }
     }
+    #[rustc_lint_diagnostics]
     pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: impl Into<DiagnosticMessage>) {
         self.diagnostic().span_warn(sp, msg)
     }
+    #[rustc_lint_diagnostics]
     pub fn span_warn_with_code<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -539,6 +541,7 @@ impl Session {
     ) {
         self.diagnostic().span_warn_with_code(sp, msg, code)
     }
+    #[rustc_lint_diagnostics]
     pub fn warn(&self, msg: impl Into<DiagnosticMessage>) {
         self.diagnostic().warn(msg)
     }
@@ -569,9 +572,11 @@ impl Session {
         self.diagnostic().delay_good_path_bug(msg)
     }
 
+    #[rustc_lint_diagnostics]
     pub fn note_without_error(&self, msg: impl Into<DiagnosticMessage>) {
         self.diagnostic().note_without_error(msg)
     }
+    #[rustc_lint_diagnostics]
     pub fn span_note_without_error<S: Into<MultiSpan>>(
         &self,
         sp: S,
@@ -579,6 +584,7 @@ impl Session {
     ) {
         self.diagnostic().span_note_without_error(sp, msg)
     }
+    #[rustc_lint_diagnostics]
     pub fn struct_note_without_error(
         &self,
         msg: impl Into<DiagnosticMessage>,
diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index f27ac24fdedd3..50ee97e980ce7 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs
@@ -1992,11 +1992,11 @@ extern "rust-intrinsic" {
     pub fn nontemporal_store<T>(ptr: *mut T, val: T);
 
     /// See documentation of `<*const T>::offset_from` for details.
-    #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "92980")]
+    #[rustc_const_stable(feature = "const_ptr_offset_from", since = "1.65.0")]
     pub fn ptr_offset_from<T>(ptr: *const T, base: *const T) -> isize;
 
     /// See documentation of `<*const T>::sub_ptr` for details.
-    #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "92980")]
+    #[rustc_const_unstable(feature = "const_ptr_sub_ptr", issue = "95892")]
     pub fn ptr_offset_from_unsigned<T>(ptr: *const T, base: *const T) -> usize;
 
     /// See documentation of `<*const T>::guaranteed_eq` for details.
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index afec497ee44d9..bf75796f1fcb2 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -130,7 +130,6 @@
 #![feature(const_replace)]
 #![feature(const_ptr_as_ref)]
 #![feature(const_ptr_is_null)]
-#![feature(const_ptr_offset_from)]
 #![feature(const_ptr_read)]
 #![feature(const_ptr_write)]
 #![feature(const_raw_ptr_comparison)]
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index 3a115a8b8b6c6..0bd9c8e9acfcb 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -457,11 +457,12 @@ macro_rules! r#try {
 ///
 /// A module can import both `std::fmt::Write` and `std::io::Write` and call `write!` on objects
 /// implementing either, as objects do not typically implement both. However, the module must
-/// import the traits qualified so their names do not conflict:
+/// avoid conflict between the trait names, such as by importing them as `_` or otherwise renaming
+/// them:
 ///
 /// ```
-/// use std::fmt::Write as FmtWrite;
-/// use std::io::Write as IoWrite;
+/// use std::fmt::Write as _;
+/// use std::io::Write as _;
 ///
 /// fn main() -> Result<(), Box<dyn std::error::Error>> {
 ///     let mut s = String::new();
@@ -474,6 +475,23 @@ macro_rules! r#try {
 /// }
 /// ```
 ///
+/// If you also need the trait names themselves, such as to implement one or both on your types,
+/// import the containing module and then name them with a prefix:
+///
+/// ```
+/// # #![allow(unused_imports)]
+/// use std::fmt::{self, Write as _};
+/// use std::io::{self, Write as _};
+///
+/// struct Example;
+///
+/// impl fmt::Write for Example {
+///     fn write_str(&mut self, _s: &str) -> core::fmt::Result {
+///          unimplemented!();
+///     }
+/// }
+/// ```
+///
 /// Note: This macro can be used in `no_std` setups as well.
 /// In a `no_std` setup you are responsible for the implementation details of the components.
 ///
@@ -526,25 +544,6 @@ macro_rules! write {
 ///     Ok(())
 /// }
 /// ```
-///
-/// A module can import both `std::fmt::Write` and `std::io::Write` and call `write!` on objects
-/// implementing either, as objects do not typically implement both. However, the module must
-/// import the traits qualified so their names do not conflict:
-///
-/// ```
-/// use std::fmt::Write as FmtWrite;
-/// use std::io::Write as IoWrite;
-///
-/// fn main() -> Result<(), Box<dyn std::error::Error>> {
-///     let mut s = String::new();
-///     let mut v = Vec::new();
-///
-///     writeln!(&mut s, "{} {}", "abc", 123)?; // uses fmt::Write::write_fmt
-///     writeln!(&mut v, "s = {:?}", s)?; // uses io::Write::write_fmt
-///     assert_eq!(v, b"s = \"abc 123\\n\"\n");
-///     Ok(())
-/// }
-/// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[cfg_attr(not(test), rustc_diagnostic_item = "writeln_macro")]
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index c25b159c533a1..08fbb79fa654c 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -641,7 +641,7 @@ impl<T: ?Sized> *const T {
     /// }
     /// ```
     #[stable(feature = "ptr_offset_from", since = "1.47.0")]
-    #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "92980")]
+    #[rustc_const_stable(feature = "const_ptr_offset_from", since = "1.65.0")]
     #[inline]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn offset_from(self, origin: *const T) -> isize
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index fff06b458c7c1..8467469053151 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -824,7 +824,7 @@ impl<T: ?Sized> *mut T {
     /// }
     /// ```
     #[stable(feature = "ptr_offset_from", since = "1.47.0")]
-    #[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "92980")]
+    #[rustc_const_stable(feature = "const_ptr_offset_from", since = "1.65.0")]
     #[inline(always)]
     #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
     pub const unsafe fn offset_from(self, origin: *const T) -> isize
diff --git a/library/std/src/fs.rs b/library/std/src/fs.rs
index c8e131b6ee14c..6e8cc15af64d0 100644
--- a/library/std/src/fs.rs
+++ b/library/std/src/fs.rs
@@ -377,6 +377,35 @@ impl File {
         OpenOptions::new().write(true).create(true).truncate(true).open(path.as_ref())
     }
 
+    /// Creates a new file in read-write mode; error if the file exists.
+    ///
+    /// This function will create a file if it does not exist, or return an error if it does. This
+    /// way, if the call succeeds, the file returned is guaranteed to be new.
+    ///
+    /// This option is useful because it is atomic. Otherwise between checking whether a file
+    /// exists and creating a new one, the file may have been created by another process (a TOCTOU
+    /// race condition / attack).
+    ///
+    /// This can also be written using
+    /// `File::options().read(true).write(true).create_new(true).open(...)`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// #![feature(file_create_new)]
+    ///
+    /// use std::fs::File;
+    ///
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut f = File::create_new("foo.txt")?;
+    ///     Ok(())
+    /// }
+    /// ```
+    #[unstable(feature = "file_create_new", issue = "none")]
+    pub fn create_new<P: AsRef<Path>>(path: P) -> io::Result<File> {
+        OpenOptions::new().read(true).write(true).create_new(true).open(path.as_ref())
+    }
+
     /// Returns a new OpenOptions object.
     ///
     /// This function returns a new OpenOptions object that you can use to
diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs
index 96addbd1a0558..17c60512d10c7 100644
--- a/library/std/src/io/mod.rs
+++ b/library/std/src/io/mod.rs
@@ -265,6 +265,8 @@ pub use self::buffered::WriterPanicked;
 #[unstable(feature = "internal_output_capture", issue = "none")]
 #[doc(no_inline, hidden)]
 pub use self::stdio::set_output_capture;
+#[unstable(feature = "is_terminal", issue = "98070")]
+pub use self::stdio::IsTerminal;
 #[unstable(feature = "print_internals", issue = "none")]
 pub use self::stdio::{_eprint, _print};
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/std/src/io/stdio.rs b/library/std/src/io/stdio.rs
index 4d3736f79146c..0c2b02c3bc360 100644
--- a/library/std/src/io/stdio.rs
+++ b/library/std/src/io/stdio.rs
@@ -7,6 +7,7 @@ use crate::io::prelude::*;
 
 use crate::cell::{Cell, RefCell};
 use crate::fmt;
+use crate::fs::File;
 use crate::io::{self, BufReader, IoSlice, IoSliceMut, LineWriter, Lines};
 use crate::pin::Pin;
 use crate::sync::atomic::{AtomicBool, Ordering};
@@ -1016,6 +1017,34 @@ where
     }
 }
 
+/// Trait to determine if a descriptor/handle refers to a terminal/tty.
+#[unstable(feature = "is_terminal", issue = "98070")]
+pub trait IsTerminal: crate::sealed::Sealed {
+    /// Returns `true` if the descriptor/handle refers to a terminal/tty.
+    ///
+    /// On platforms where Rust does not know how to detect a terminal yet, this will return
+    /// `false`. This will also return `false` if an unexpected error occurred, such as from
+    /// passing an invalid file descriptor.
+    fn is_terminal(&self) -> bool;
+}
+
+macro_rules! impl_is_terminal {
+    ($($t:ty),*$(,)?) => {$(
+        #[unstable(feature = "sealed", issue = "none")]
+        impl crate::sealed::Sealed for $t {}
+
+        #[unstable(feature = "is_terminal", issue = "98070")]
+        impl IsTerminal for $t {
+            #[inline]
+            fn is_terminal(&self) -> bool {
+                crate::sys::io::is_terminal(self)
+            }
+        }
+    )*}
+}
+
+impl_is_terminal!(File, Stdin, StdinLock<'_>, Stdout, StdoutLock<'_>, Stderr, StderrLock<'_>);
+
 #[unstable(
     feature = "print_internals",
     reason = "implementation detail which may disappear or be replaced at any time",
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 50e3acc940076..215165e1592b9 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -252,6 +252,7 @@
 #![feature(dropck_eyepatch)]
 #![feature(exhaustive_patterns)]
 #![feature(intra_doc_pointers)]
+#![feature(is_terminal)]
 #![cfg_attr(bootstrap, feature(label_break_value))]
 #![feature(lang_items)]
 #![feature(let_else)]
diff --git a/library/std/src/net/parser.rs b/library/std/src/net/parser.rs
index 069b660998559..a38031c48c862 100644
--- a/library/std/src/net/parser.rs
+++ b/library/std/src/net/parser.rs
@@ -39,8 +39,8 @@ struct Parser<'a> {
 }
 
 impl<'a> Parser<'a> {
-    fn new(input: &'a str) -> Parser<'a> {
-        Parser { state: input.as_bytes() }
+    fn new(input: &'a [u8]) -> Parser<'a> {
+        Parser { state: input }
     }
 
     /// Run a parser, and restore the pre-parse state if it fails.
@@ -273,32 +273,106 @@ impl<'a> Parser<'a> {
     }
 }
 
+impl IpAddr {
+    /// Parse an IP address from a slice of bytes.
+    ///
+    /// ```
+    /// #![feature(addr_parse_ascii)]
+    ///
+    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
+    ///
+    /// let localhost_v4 = IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1));
+    /// let localhost_v6 = IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1));
+    ///
+    /// assert_eq!(IpAddr::parse_ascii(b"127.0.0.1"), Ok(localhost_v4));
+    /// assert_eq!(IpAddr::parse_ascii(b"::1"), Ok(localhost_v6));
+    /// ```
+    #[unstable(feature = "addr_parse_ascii", issue = "101035")]
+    pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
+        Parser::new(b).parse_with(|p| p.read_ip_addr(), AddrKind::Ip)
+    }
+}
+
 #[stable(feature = "ip_addr", since = "1.7.0")]
 impl FromStr for IpAddr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<IpAddr, AddrParseError> {
-        Parser::new(s).parse_with(|p| p.read_ip_addr(), AddrKind::Ip)
+        Self::parse_ascii(s.as_bytes())
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
-impl FromStr for Ipv4Addr {
-    type Err = AddrParseError;
-    fn from_str(s: &str) -> Result<Ipv4Addr, AddrParseError> {
+impl Ipv4Addr {
+    /// Parse an IPv4 address from a slice of bytes.
+    ///
+    /// ```
+    /// #![feature(addr_parse_ascii)]
+    ///
+    /// use std::net::Ipv4Addr;
+    ///
+    /// let localhost = Ipv4Addr::new(127, 0, 0, 1);
+    ///
+    /// assert_eq!(Ipv4Addr::parse_ascii(b"127.0.0.1"), Ok(localhost));
+    /// ```
+    #[unstable(feature = "addr_parse_ascii", issue = "101035")]
+    pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
         // don't try to parse if too long
-        if s.len() > 15 {
+        if b.len() > 15 {
             Err(AddrParseError(AddrKind::Ipv4))
         } else {
-            Parser::new(s).parse_with(|p| p.read_ipv4_addr(), AddrKind::Ipv4)
+            Parser::new(b).parse_with(|p| p.read_ipv4_addr(), AddrKind::Ipv4)
         }
     }
 }
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl FromStr for Ipv4Addr {
+    type Err = AddrParseError;
+    fn from_str(s: &str) -> Result<Ipv4Addr, AddrParseError> {
+        Self::parse_ascii(s.as_bytes())
+    }
+}
+
+impl Ipv6Addr {
+    /// Parse an IPv6 address from a slice of bytes.
+    ///
+    /// ```
+    /// #![feature(addr_parse_ascii)]
+    ///
+    /// use std::net::Ipv6Addr;
+    ///
+    /// let localhost = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
+    ///
+    /// assert_eq!(Ipv6Addr::parse_ascii(b"::1"), Ok(localhost));
+    /// ```
+    #[unstable(feature = "addr_parse_ascii", issue = "101035")]
+    pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
+        Parser::new(b).parse_with(|p| p.read_ipv6_addr(), AddrKind::Ipv6)
+    }
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl FromStr for Ipv6Addr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<Ipv6Addr, AddrParseError> {
-        Parser::new(s).parse_with(|p| p.read_ipv6_addr(), AddrKind::Ipv6)
+        Self::parse_ascii(s.as_bytes())
+    }
+}
+
+impl SocketAddrV4 {
+    /// Parse an IPv4 socket address from a slice of bytes.
+    ///
+    /// ```
+    /// #![feature(addr_parse_ascii)]
+    ///
+    /// use std::net::{Ipv4Addr, SocketAddrV4};
+    ///
+    /// let socket = SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 8080);
+    ///
+    /// assert_eq!(SocketAddrV4::parse_ascii(b"127.0.0.1:8080"), Ok(socket));
+    /// ```
+    #[unstable(feature = "addr_parse_ascii", issue = "101035")]
+    pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
+        Parser::new(b).parse_with(|p| p.read_socket_addr_v4(), AddrKind::SocketV4)
     }
 }
 
@@ -306,7 +380,25 @@ impl FromStr for Ipv6Addr {
 impl FromStr for SocketAddrV4 {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<SocketAddrV4, AddrParseError> {
-        Parser::new(s).parse_with(|p| p.read_socket_addr_v4(), AddrKind::SocketV4)
+        Self::parse_ascii(s.as_bytes())
+    }
+}
+
+impl SocketAddrV6 {
+    /// Parse an IPv6 socket address from a slice of bytes.
+    ///
+    /// ```
+    /// #![feature(addr_parse_ascii)]
+    ///
+    /// use std::net::{Ipv6Addr, SocketAddrV6};
+    ///
+    /// let socket = SocketAddrV6::new(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 1), 8080, 0, 0);
+    ///
+    /// assert_eq!(SocketAddrV6::parse_ascii(b"[2001:db8::1]:8080"), Ok(socket));
+    /// ```
+    #[unstable(feature = "addr_parse_ascii", issue = "101035")]
+    pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
+        Parser::new(b).parse_with(|p| p.read_socket_addr_v6(), AddrKind::SocketV6)
     }
 }
 
@@ -314,7 +406,27 @@ impl FromStr for SocketAddrV4 {
 impl FromStr for SocketAddrV6 {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<SocketAddrV6, AddrParseError> {
-        Parser::new(s).parse_with(|p| p.read_socket_addr_v6(), AddrKind::SocketV6)
+        Self::parse_ascii(s.as_bytes())
+    }
+}
+
+impl SocketAddr {
+    /// Parse a socket address from a slice of bytes.
+    ///
+    /// ```
+    /// #![feature(addr_parse_ascii)]
+    ///
+    /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
+    ///
+    /// let socket_v4 = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), 8080);
+    /// let socket_v6 = SocketAddr::new(IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1)), 8080);
+    ///
+    /// assert_eq!(SocketAddr::parse_ascii(b"127.0.0.1:8080"), Ok(socket_v4));
+    /// assert_eq!(SocketAddr::parse_ascii(b"[::1]:8080"), Ok(socket_v6));
+    /// ```
+    #[unstable(feature = "addr_parse_ascii", issue = "101035")]
+    pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
+        Parser::new(b).parse_with(|p| p.read_socket_addr(), AddrKind::Socket)
     }
 }
 
@@ -322,7 +434,7 @@ impl FromStr for SocketAddrV6 {
 impl FromStr for SocketAddr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<SocketAddr, AddrParseError> {
-        Parser::new(s).parse_with(|p| p.read_socket_addr(), AddrKind::Socket)
+        Self::parse_ascii(s.as_bytes())
     }
 }
 
diff --git a/library/std/src/os/fd/owned.rs b/library/std/src/os/fd/owned.rs
index a463bc41db7aa..2475c99923336 100644
--- a/library/std/src/os/fd/owned.rs
+++ b/library/std/src/os/fd/owned.rs
@@ -191,6 +191,23 @@ impl fmt::Debug for OwnedFd {
     }
 }
 
+macro_rules! impl_is_terminal {
+    ($($t:ty),*$(,)?) => {$(
+        #[unstable(feature = "sealed", issue = "none")]
+        impl crate::sealed::Sealed for $t {}
+
+        #[unstable(feature = "is_terminal", issue = "98070")]
+        impl crate::io::IsTerminal for $t {
+            #[inline]
+            fn is_terminal(&self) -> bool {
+                crate::sys::io::is_terminal(self)
+            }
+        }
+    )*}
+}
+
+impl_is_terminal!(BorrowedFd<'_>, OwnedFd);
+
 /// A trait to borrow the file descriptor from an underlying object.
 ///
 /// This is only available on unix platforms and must be imported in order to
diff --git a/library/std/src/os/mod.rs b/library/std/src/os/mod.rs
index 6fbaa42c76846..65e53d9e22e15 100644
--- a/library/std/src/os/mod.rs
+++ b/library/std/src/os/mod.rs
@@ -147,4 +147,4 @@ pub mod solid;
 pub mod vxworks;
 
 #[cfg(any(unix, target_os = "wasi", doc))]
-mod fd;
+pub(crate) mod fd;
diff --git a/library/std/src/os/windows/io/handle.rs b/library/std/src/os/windows/io/handle.rs
index 16cc8fa2783ee..1dfecc57338a7 100644
--- a/library/std/src/os/windows/io/handle.rs
+++ b/library/std/src/os/windows/io/handle.rs
@@ -384,6 +384,23 @@ impl fmt::Debug for OwnedHandle {
     }
 }
 
+macro_rules! impl_is_terminal {
+    ($($t:ty),*$(,)?) => {$(
+        #[unstable(feature = "sealed", issue = "none")]
+        impl crate::sealed::Sealed for $t {}
+
+        #[unstable(feature = "is_terminal", issue = "98070")]
+        impl crate::io::IsTerminal for $t {
+            #[inline]
+            fn is_terminal(&self) -> bool {
+                crate::sys::io::is_terminal(self)
+            }
+        }
+    )*}
+}
+
+impl_is_terminal!(BorrowedHandle<'_>, OwnedHandle);
+
 /// A trait to borrow the handle from an underlying object.
 #[stable(feature = "io_safety", since = "1.63.0")]
 pub trait AsHandle {
diff --git a/library/std/src/sys/unix/io.rs b/library/std/src/sys/unix/io.rs
index deb5ee76bd035..8d189059d3641 100644
--- a/library/std/src/sys/unix/io.rs
+++ b/library/std/src/sys/unix/io.rs
@@ -1,4 +1,6 @@
 use crate::marker::PhantomData;
+use crate::os::fd::owned::AsFd;
+use crate::os::fd::raw::AsRawFd;
 use crate::slice;
 
 use libc::{c_void, iovec};
@@ -74,3 +76,8 @@ impl<'a> IoSliceMut<'a> {
         unsafe { slice::from_raw_parts_mut(self.vec.iov_base as *mut u8, self.vec.iov_len) }
     }
 }
+
+pub fn is_terminal(fd: &impl AsFd) -> bool {
+    let fd = fd.as_fd();
+    unsafe { libc::isatty(fd.as_raw_fd()) != 0 }
+}
diff --git a/library/std/src/sys/unsupported/io.rs b/library/std/src/sys/unsupported/io.rs
index d5f475b4310fd..82610ffab7e1e 100644
--- a/library/std/src/sys/unsupported/io.rs
+++ b/library/std/src/sys/unsupported/io.rs
@@ -45,3 +45,7 @@ impl<'a> IoSliceMut<'a> {
         self.0
     }
 }
+
+pub fn is_terminal<T>(_: &T) -> bool {
+    false
+}
diff --git a/library/std/src/sys/wasi/io.rs b/library/std/src/sys/wasi/io.rs
index ee017d13a4ca0..bd9f8872333e2 100644
--- a/library/std/src/sys/wasi/io.rs
+++ b/library/std/src/sys/wasi/io.rs
@@ -1,6 +1,8 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 
 use crate::marker::PhantomData;
+use crate::os::fd::owned::AsFd;
+use crate::os::fd::raw::AsRawFd;
 use crate::slice;
 
 #[derive(Copy, Clone)]
@@ -71,3 +73,8 @@ impl<'a> IoSliceMut<'a> {
         unsafe { slice::from_raw_parts_mut(self.vec.buf as *mut u8, self.vec.buf_len) }
     }
 }
+
+pub fn is_terminal(fd: &impl AsFd) -> bool {
+    let fd = fd.as_fd();
+    unsafe { libc::isatty(fd.as_raw_fd()) != 0 }
+}
diff --git a/library/std/src/sys/windows/c.rs b/library/std/src/sys/windows/c.rs
index ef3f6a9ba1755..09ca02afea241 100644
--- a/library/std/src/sys/windows/c.rs
+++ b/library/std/src/sys/windows/c.rs
@@ -125,6 +125,8 @@ pub const SECURITY_SQOS_PRESENT: DWORD = 0x00100000;
 
 pub const FIONBIO: c_ulong = 0x8004667e;
 
+pub const MAX_PATH: usize = 260;
+
 #[repr(C)]
 #[derive(Copy)]
 pub struct WIN32_FIND_DATAW {
@@ -521,6 +523,12 @@ pub struct SYMBOLIC_LINK_REPARSE_BUFFER {
     pub PathBuffer: WCHAR,
 }
 
+#[repr(C)]
+pub struct FILE_NAME_INFO {
+    pub FileNameLength: DWORD,
+    pub FileName: [WCHAR; 1],
+}
+
 #[repr(C)]
 pub struct MOUNT_POINT_REPARSE_BUFFER {
     pub SubstituteNameOffset: c_ushort,
diff --git a/library/std/src/sys/windows/io.rs b/library/std/src/sys/windows/io.rs
index fb06df1f80cda..7e7518b6d8905 100644
--- a/library/std/src/sys/windows/io.rs
+++ b/library/std/src/sys/windows/io.rs
@@ -1,6 +1,10 @@
 use crate::marker::PhantomData;
+use crate::mem::size_of;
+use crate::os::windows::io::{AsHandle, AsRawHandle, BorrowedHandle};
 use crate::slice;
 use crate::sys::c;
+use core;
+use libc;
 
 #[derive(Copy, Clone)]
 #[repr(transparent)]
@@ -78,3 +82,66 @@ impl<'a> IoSliceMut<'a> {
         unsafe { slice::from_raw_parts_mut(self.vec.buf as *mut u8, self.vec.len as usize) }
     }
 }
+
+pub fn is_terminal(h: &impl AsHandle) -> bool {
+    unsafe { handle_is_console(h.as_handle()) }
+}
+
+unsafe fn handle_is_console(handle: BorrowedHandle<'_>) -> bool {
+    let handle = handle.as_raw_handle();
+
+    // A null handle means the process has no console.
+    if handle.is_null() {
+        return false;
+    }
+
+    let mut out = 0;
+    if c::GetConsoleMode(handle, &mut out) != 0 {
+        // False positives aren't possible. If we got a console then we definitely have a console.
+        return true;
+    }
+
+    // At this point, we *could* have a false negative. We can determine that this is a true
+    // negative if we can detect the presence of a console on any of the standard I/O streams. If
+    // another stream has a console, then we know we're in a Windows console and can therefore
+    // trust the negative.
+    for std_handle in [c::STD_INPUT_HANDLE, c::STD_OUTPUT_HANDLE, c::STD_ERROR_HANDLE] {
+        let std_handle = c::GetStdHandle(std_handle);
+        if !std_handle.is_null()
+            && std_handle != handle
+            && c::GetConsoleMode(std_handle, &mut out) != 0
+        {
+            return false;
+        }
+    }
+
+    // Otherwise, we fall back to an msys hack to see if we can detect the presence of a pty.
+    msys_tty_on(handle)
+}
+
+unsafe fn msys_tty_on(handle: c::HANDLE) -> bool {
+    let size = size_of::<c::FILE_NAME_INFO>() + c::MAX_PATH * size_of::<c::WCHAR>();
+    let mut name_info_bytes = vec![0u8; size];
+    let res = c::GetFileInformationByHandleEx(
+        handle,
+        c::FileNameInfo,
+        name_info_bytes.as_mut_ptr() as *mut libc::c_void,
+        size as u32,
+    );
+    if res == 0 {
+        return false;
+    }
+    let name_info: &c::FILE_NAME_INFO = &*(name_info_bytes.as_ptr() as *const c::FILE_NAME_INFO);
+    let name_len = name_info.FileNameLength as usize / 2;
+    // Offset to get the `FileName` field.
+    let name_ptr = name_info_bytes.as_ptr().offset(size_of::<c::DWORD>() as isize).cast::<u16>();
+    let s = core::slice::from_raw_parts(name_ptr, name_len);
+    let name = String::from_utf16_lossy(s);
+    // This checks whether 'pty' exists in the file name, which indicates that
+    // a pseudo-terminal is attached. To mitigate against false positives
+    // (e.g., an actual file name that contains 'pty'), we also require that
+    // either the strings 'msys-' or 'cygwin-' are in the file name as well.)
+    let is_msys = name.contains("msys-") || name.contains("cygwin-");
+    let is_pty = name.contains("-pty");
+    is_msys && is_pty
+}
diff --git a/library/test/src/cli.rs b/library/test/src/cli.rs
index f981b9c495476..8be32183fe780 100644
--- a/library/test/src/cli.rs
+++ b/library/test/src/cli.rs
@@ -3,9 +3,9 @@
 use std::env;
 use std::path::PathBuf;
 
-use super::helpers::isatty;
 use super::options::{ColorConfig, Options, OutputFormat, RunIgnored};
 use super::time::TestTimeOptions;
+use std::io::{self, IsTerminal};
 
 #[derive(Debug)]
 pub struct TestOpts {
@@ -32,7 +32,7 @@ pub struct TestOpts {
 impl TestOpts {
     pub fn use_color(&self) -> bool {
         match self.color {
-            ColorConfig::AutoColor => !self.nocapture && isatty::stdout_isatty(),
+            ColorConfig::AutoColor => !self.nocapture && io::stdout().is_terminal(),
             ColorConfig::AlwaysColor => true,
             ColorConfig::NeverColor => false,
         }
diff --git a/library/test/src/helpers/isatty.rs b/library/test/src/helpers/isatty.rs
deleted file mode 100644
index 874ecc3764572..0000000000000
--- a/library/test/src/helpers/isatty.rs
+++ /dev/null
@@ -1,32 +0,0 @@
-//! Helper module which provides a function to test
-//! if stdout is a tty.
-
-cfg_if::cfg_if! {
-    if #[cfg(unix)] {
-        pub fn stdout_isatty() -> bool {
-            unsafe { libc::isatty(libc::STDOUT_FILENO) != 0 }
-        }
-    } else if #[cfg(windows)] {
-        pub fn stdout_isatty() -> bool {
-            type DWORD = u32;
-            type BOOL = i32;
-            type HANDLE = *mut u8;
-            type LPDWORD = *mut u32;
-            const STD_OUTPUT_HANDLE: DWORD = -11i32 as DWORD;
-            extern "system" {
-                fn GetStdHandle(which: DWORD) -> HANDLE;
-                fn GetConsoleMode(hConsoleHandle: HANDLE, lpMode: LPDWORD) -> BOOL;
-            }
-            unsafe {
-                let handle = GetStdHandle(STD_OUTPUT_HANDLE);
-                let mut out = 0;
-                GetConsoleMode(handle, &mut out) != 0
-            }
-        }
-    } else {
-        // FIXME: Implement isatty on SGX
-        pub fn stdout_isatty() -> bool {
-            false
-        }
-    }
-}
diff --git a/library/test/src/helpers/mod.rs b/library/test/src/helpers/mod.rs
index 049cadf86a6d0..6f366a911e8cd 100644
--- a/library/test/src/helpers/mod.rs
+++ b/library/test/src/helpers/mod.rs
@@ -3,6 +3,5 @@
 
 pub mod concurrency;
 pub mod exit_code;
-pub mod isatty;
 pub mod metrics;
 pub mod shuffle;
diff --git a/library/test/src/lib.rs b/library/test/src/lib.rs
index 3b7193adcc758..f595e2a74d4ad 100644
--- a/library/test/src/lib.rs
+++ b/library/test/src/lib.rs
@@ -17,6 +17,7 @@
 #![doc(test(attr(deny(warnings))))]
 #![feature(bench_black_box)]
 #![feature(internal_output_capture)]
+#![feature(is_terminal)]
 #![feature(staged_api)]
 #![feature(process_exitcode_internals)]
 #![feature(test)]
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index baad0c75295a5..c759d9b88e2ff 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -1514,7 +1514,15 @@ note: if you're sure you want to do this, please open an issue as to why. In the
 
         test_args.append(&mut builder.config.cmd.test_args());
 
-        cmd.args(&test_args);
+        // On Windows, replace forward slashes in test-args by backslashes
+        // so the correct filters are passed to libtest
+        if cfg!(windows) {
+            let test_args_win: Vec<String> =
+                test_args.iter().map(|s| s.replace("/", "\\")).collect();
+            cmd.args(&test_args_win);
+        } else {
+            cmd.args(&test_args);
+        }
 
         if builder.is_verbose() {
             cmd.arg("--verbose");
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index 912601dda20b1..4fc54eb87d6bc 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -371,16 +371,21 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                     }
                     clean::ImportKind::Glob => String::new(),
                 };
+                let stab_tags = stab_tags.unwrap_or_default();
+                let (stab_tags_before, stab_tags_after) = if stab_tags.is_empty() {
+                    ("", "")
+                } else {
+                    ("<div class=\"item-right docblock-short\">", "</div>")
+                };
                 write!(
                     w,
                     "<div class=\"item-left {stab}{add}import-item\"{id}>\
                          <code>{vis}{imp}</code>\
                      </div>\
-                     <div class=\"item-right docblock-short\">{stab_tags}</div>",
+                     {stab_tags_before}{stab_tags}{stab_tags_after}",
                     stab = stab.unwrap_or_default(),
                     vis = myitem.visibility.print_with_space(myitem.item_id, cx),
                     imp = import.print(cx),
-                    stab_tags = stab_tags.unwrap_or_default(),
                 );
                 w.write_str(ITEM_TABLE_ROW_CLOSE);
             }
@@ -412,6 +417,12 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
 
                 let doc_value = myitem.doc_value().unwrap_or_default();
                 w.write_str(ITEM_TABLE_ROW_OPEN);
+                let docs = MarkdownSummaryLine(&doc_value, &myitem.links(cx)).into_string();
+                let (docs_before, docs_after) = if docs.is_empty() {
+                    ("", "")
+                } else {
+                    ("<div class=\"item-right docblock-short\">", "</div>")
+                };
                 write!(
                     w,
                     "<div class=\"item-left {stab}{add}module-item\">\
@@ -420,11 +431,10 @@ fn item_module(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Item, items:
                         {unsafety_flag}\
                         {stab_tags}\
                      </div>\
-                     <div class=\"item-right docblock-short\">{docs}</div>",
+                     {docs_before}{docs}{docs_after}",
                     name = myitem.name.unwrap(),
                     visibility_emoji = visibility_emoji,
                     stab_tags = extra_info_tags(myitem, item, cx.tcx()),
-                    docs = MarkdownSummaryLine(&doc_value, &myitem.links(cx)).into_string(),
                     class = myitem.type_(),
                     add = add,
                     stab = stab.unwrap_or_default(),
diff --git a/src/test/codegen/external-no-mangle-statics.rs b/src/test/codegen/external-no-mangle-statics.rs
index 6274434cd8fcc..c6ecb7aa96abc 100644
--- a/src/test/codegen/external-no-mangle-statics.rs
+++ b/src/test/codegen/external-no-mangle-statics.rs
@@ -1,12 +1,11 @@
 // revisions: lib staticlib
 // ignore-emscripten default visibility is hidden
 // compile-flags: -O
+// [lib] compile-flags: --crate-type lib
+// [staticlib] compile-flags: --crate-type staticlib
 // `#[no_mangle]`d static variables always have external linkage, i.e., no `internal` in their
 // definitions
 
-#![cfg_attr(lib, crate_type = "lib")]
-#![cfg_attr(staticlib, crate_type = "staticlib")]
-
 // CHECK: @A = local_unnamed_addr constant
 #[no_mangle]
 static A: u8 = 0;
diff --git a/src/test/run-make/incremental-session-fail/Makefile b/src/test/run-make/incremental-session-fail/Makefile
index 0461bb926e76e..6ce1370927bc1 100644
--- a/src/test/run-make/incremental-session-fail/Makefile
+++ b/src/test/run-make/incremental-session-fail/Makefile
@@ -9,6 +9,6 @@ all:
 	touch $(SESSION_DIR)
 	# Check exit code is 1 for an error, and not 101 for ICE.
 	$(RUSTC) foo.rs --crate-type=rlib -C incremental=$(SESSION_DIR) > $(OUTPUT_FILE) 2>&1; [ $$? -eq 1 ]
-	$(CGREP) "Could not create incremental compilation crate directory" < $(OUTPUT_FILE)
+	$(CGREP) "could not create incremental compilation crate directory" < $(OUTPUT_FILE)
 	# -v tests are fragile, hopefully this text won't change
 	$(CGREP) -v "internal compiler error" < $(OUTPUT_FILE)
diff --git a/src/test/rustdoc-gui/item-summary-table.goml b/src/test/rustdoc-gui/item-summary-table.goml
index 6bf4e288c4377..4bff32b3d5db1 100644
--- a/src/test/rustdoc-gui/item-summary-table.goml
+++ b/src/test/rustdoc-gui/item-summary-table.goml
@@ -3,4 +3,4 @@ goto: file://|DOC_PATH|/lib2/summary_table/index.html
 // We check that we picked the right item first.
 assert-text: (".item-table .item-left", "Foo")
 // Then we check that its summary is empty.
-assert-text: (".item-table .item-right", "")
+assert-false: ".item-table .item-right"
diff --git a/src/test/rustdoc/short-docblock-codeblock.rs b/src/test/rustdoc/short-docblock-codeblock.rs
index c6b318b0677ce..3c5fa7b36adbf 100644
--- a/src/test/rustdoc/short-docblock-codeblock.rs
+++ b/src/test/rustdoc/short-docblock-codeblock.rs
@@ -1,8 +1,6 @@
 #![crate_name = "foo"]
 
-// @has foo/index.html '//*[@class="item-right docblock-short"]' ""
-// @!has foo/index.html '//*[@class="item-right docblock-short"]' "Some text."
-// @!has foo/index.html '//*[@class="item-right docblock-short"]' "let x = 12;"
+// @count foo/index.html '//*[@class="item-right docblock-short"]' 0
 
 /// ```
 /// let x = 12;
diff --git a/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs b/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
index 16da25c402b57..8bd0859ee149f 100644
--- a/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
+++ b/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
@@ -167,8 +167,8 @@ enum P {
 #[derive(SessionSubdiagnostic)]
 enum Q {
     #[bar]
-//~^ ERROR `#[bar]` is not a valid attribute
-//~^^ ERROR cannot find attribute `bar` in this scope
+    //~^ ERROR `#[bar]` is not a valid attribute
+    //~^^ ERROR cannot find attribute `bar` in this scope
     A {
         #[primary_span]
         span: Span,
@@ -179,8 +179,8 @@ enum Q {
 #[derive(SessionSubdiagnostic)]
 enum R {
     #[bar = "..."]
-//~^ ERROR `#[bar = ...]` is not a valid attribute
-//~^^ ERROR cannot find attribute `bar` in this scope
+    //~^ ERROR `#[bar = ...]` is not a valid attribute
+    //~^^ ERROR cannot find attribute `bar` in this scope
     A {
         #[primary_span]
         span: Span,
@@ -191,8 +191,8 @@ enum R {
 #[derive(SessionSubdiagnostic)]
 enum S {
     #[bar = 4]
-//~^ ERROR `#[bar = ...]` is not a valid attribute
-//~^^ ERROR cannot find attribute `bar` in this scope
+    //~^ ERROR `#[bar = ...]` is not a valid attribute
+    //~^^ ERROR cannot find attribute `bar` in this scope
     A {
         #[primary_span]
         span: Span,
@@ -203,8 +203,8 @@ enum S {
 #[derive(SessionSubdiagnostic)]
 enum T {
     #[bar("...")]
-//~^ ERROR `#[bar("...")]` is not a valid attribute
-//~^^ ERROR cannot find attribute `bar` in this scope
+    //~^ ERROR `#[bar(...)]` is not a valid attribute
+    //~^^ ERROR cannot find attribute `bar` in this scope
     A {
         #[primary_span]
         span: Span,
@@ -215,7 +215,7 @@ enum T {
 #[derive(SessionSubdiagnostic)]
 enum U {
     #[label(code = "...")]
-//~^ ERROR diagnostic slug must be first argument of a `#[label(...)]` attribute
+    //~^ ERROR diagnostic slug must be first argument of a `#[label(...)]` attribute
     A {
         #[primary_span]
         span: Span,
@@ -232,7 +232,7 @@ enum V {
         var: String,
     },
     B {
-//~^ ERROR subdiagnostic kind not specified
+    //~^ ERROR subdiagnostic kind not specified
         #[primary_span]
         span: Span,
         var: String,
@@ -310,10 +310,8 @@ union AC {
 #[derive(SessionSubdiagnostic)]
 #[label(parser::add_paren)]
 //~^ NOTE previously specified here
-//~^^ NOTE previously specified here
 #[label(parser::add_paren)]
 //~^ ERROR specified multiple times
-//~^^ ERROR specified multiple times
 struct AD {
     #[primary_span]
     span: Span,
@@ -331,16 +329,16 @@ struct AE {
 #[label(parser::add_paren)]
 struct AF {
     #[primary_span]
-//~^ NOTE previously specified here
+    //~^ NOTE previously specified here
     span_a: Span,
     #[primary_span]
-//~^ ERROR specified multiple times
+    //~^ ERROR specified multiple times
     span_b: Span,
 }
 
 #[derive(SessionSubdiagnostic)]
 struct AG {
-//~^ ERROR subdiagnostic kind not specified
+    //~^ ERROR subdiagnostic kind not specified
     #[primary_span]
     span: Span,
 }
@@ -392,27 +390,25 @@ struct AK {
     #[primary_span]
     span: Span,
     #[applicability]
-//~^ NOTE previously specified here
+    //~^ NOTE previously specified here
     applicability_a: Applicability,
     #[applicability]
-//~^ ERROR specified multiple times
+    //~^ ERROR specified multiple times
     applicability_b: Applicability,
 }
 
 #[derive(SessionSubdiagnostic)]
 #[suggestion(parser::add_paren, code = "...")]
-//~^ ERROR suggestion without `applicability`
 struct AL {
     #[primary_span]
     span: Span,
     #[applicability]
-//~^ ERROR the `#[applicability]` attribute can only be applied to fields of type `Applicability`
+    //~^ ERROR the `#[applicability]` attribute can only be applied to fields of type `Applicability`
     applicability: Span,
 }
 
 #[derive(SessionSubdiagnostic)]
 #[suggestion(parser::add_paren, code = "...")]
-//~^ ERROR suggestion without `applicability`
 struct AM {
     #[primary_span]
     span: Span,
@@ -448,8 +444,7 @@ struct AQ;
 
 #[derive(SessionSubdiagnostic)]
 #[suggestion(parser::add_paren, code = "...")]
-//~^ ERROR suggestion without `applicability`
-//~^^ ERROR suggestion without `#[primary_span]` field
+//~^ ERROR suggestion without `#[primary_span]` field
 struct AR {
     var: String,
 }
@@ -520,3 +515,120 @@ struct AZ {
     #[primary_span]
     span: Span,
 }
+
+#[derive(SessionSubdiagnostic)]
+#[suggestion(parser::add_paren, code = "...")]
+//~^ ERROR suggestion without `#[primary_span]` field
+struct BA {
+    #[suggestion_part]
+    //~^ ERROR `#[suggestion_part]` is not a valid attribute
+    span: Span,
+    #[suggestion_part(code = "...")]
+    //~^ ERROR `#[suggestion_part(...)]` is not a valid attribute
+    span2: Span,
+    #[applicability]
+    applicability: Applicability,
+    var: String,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, code = "...", applicability = "machine-applicable")]
+//~^ ERROR multipart suggestion without any `#[suggestion_part(...)]` fields
+//~| ERROR `code` is not a valid nested attribute of a `multipart_suggestion` attribute
+struct BBa {
+    var: String,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BBb {
+    #[suggestion_part]
+    //~^ ERROR `#[suggestion_part(...)]` attribute without `code = "..."`
+    span1: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BBc {
+    #[suggestion_part()]
+    //~^ ERROR `#[suggestion_part(...)]` attribute without `code = "..."`
+    span1: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren)]
+//~^ ERROR multipart suggestion without any `#[suggestion_part(...)]` fields
+struct BC {
+    #[primary_span]
+    //~^ ERROR `#[primary_span]` is not a valid attribute
+    span: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren)]
+struct BD {
+    #[suggestion_part]
+    //~^ ERROR `#[suggestion_part(...)]` attribute without `code = "..."`
+    span1: Span,
+    #[suggestion_part()]
+    //~^ ERROR `#[suggestion_part(...)]` attribute without `code = "..."`
+    span2: Span,
+    #[suggestion_part(foo = "bar")]
+    //~^ ERROR `#[suggestion_part(foo = ...)]` is not a valid attribute
+    span4: Span,
+    #[suggestion_part(code = "...")]
+    //~^ ERROR the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
+    s1: String,
+    #[suggestion_part()]
+    //~^ ERROR the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
+    s2: String,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BE {
+    #[suggestion_part(code = "...", code = ",,,")]
+    //~^ ERROR specified multiple times
+    //~| NOTE previously specified here
+    span: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BF {
+    #[suggestion_part(code = "(")]
+    first: Span,
+    #[suggestion_part(code = ")")]
+    second: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren)]
+struct BG {
+    #[applicability]
+    appl: Applicability,
+    #[suggestion_part(code = "(")]
+    first: Span,
+    #[suggestion_part(code = ")")]
+    second: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+//~^ NOTE previously specified here
+struct BH {
+    #[applicability]
+    //~^ ERROR specified multiple times
+    appl: Applicability,
+    #[suggestion_part(code = "(")]
+    first: Span,
+    #[suggestion_part(code = ")")]
+    second: Span,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+struct BI {
+    #[suggestion_part(code = "")]
+    spans: Vec<Span>,
+}
diff --git a/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr b/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
index a289c4fffd936..f91a9d4ce48e9 100644
--- a/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
+++ b/src/test/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
@@ -65,16 +65,16 @@ LL | #[label()]
    | ^^^^^^^^^^
 
 error: `code` is not a valid nested attribute of a `label` attribute
-  --> $DIR/subdiagnostic-derive.rs:137:1
+  --> $DIR/subdiagnostic-derive.rs:137:28
    |
 LL | #[label(parser::add_paren, code = "...")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                            ^^^^^^^^^^^^
 
 error: `applicability` is not a valid nested attribute of a `label` attribute
-  --> $DIR/subdiagnostic-derive.rs:146:1
+  --> $DIR/subdiagnostic-derive.rs:146:28
    |
 LL | #[label(parser::add_paren, applicability = "machine-applicable")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: unsupported type attribute for subdiagnostic enum
   --> $DIR/subdiagnostic-derive.rs:155:1
@@ -100,13 +100,11 @@ error: `#[bar = ...]` is not a valid attribute
 LL |     #[bar = 4]
    |     ^^^^^^^^^^
 
-error: `#[bar("...")]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:205:11
+error: `#[bar(...)]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:205:5
    |
 LL |     #[bar("...")]
-   |           ^^^^^
-   |
-   = help: first argument of the attribute should be the diagnostic slug
+   |     ^^^^^^^^^^^^^
 
 error: diagnostic slug must be first argument of a `#[label(...)]` attribute
   --> $DIR/subdiagnostic-derive.rs:217:5
@@ -163,6 +161,8 @@ error: `#[bar(...)]` is not a valid attribute
    |
 LL |     #[bar("...")]
    |     ^^^^^^^^^^^^^
+   |
+   = help: only `primary_span`, `applicability` and `skip_arg` are valid field attributes
 
 error: unexpected unsupported untagged union
   --> $DIR/subdiagnostic-derive.rs:304:1
@@ -175,19 +175,7 @@ LL | | }
    | |_^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:314:1
-   |
-LL | #[label(parser::add_paren)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:311:1
-   |
-LL | #[label(parser::add_paren)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:314:1
+  --> $DIR/subdiagnostic-derive.rs:313:1
    |
 LL | #[label(parser::add_paren)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -199,7 +187,7 @@ LL | #[label(parser::add_paren)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `#[label(parser::add_paren)]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:323:28
+  --> $DIR/subdiagnostic-derive.rs:321:28
    |
 LL | #[label(parser::add_paren, parser::add_paren)]
    |                            ^^^^^^^^^^^^^^^^^
@@ -207,133 +195,225 @@ LL | #[label(parser::add_paren, parser::add_paren)]
    = help: a diagnostic slug must be the first argument to the attribute
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:336:5
+  --> $DIR/subdiagnostic-derive.rs:334:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:333:5
+  --> $DIR/subdiagnostic-derive.rs:331:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
 
 error: subdiagnostic kind not specified
-  --> $DIR/subdiagnostic-derive.rs:342:8
+  --> $DIR/subdiagnostic-derive.rs:340:8
    |
 LL | struct AG {
    |        ^^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:379:47
+  --> $DIR/subdiagnostic-derive.rs:377:47
    |
 LL | #[suggestion(parser::add_paren, code = "...", code = "...")]
    |                                               ^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:379:33
+  --> $DIR/subdiagnostic-derive.rs:377:33
    |
 LL | #[suggestion(parser::add_paren, code = "...", code = "...")]
    |                                 ^^^^^^^^^^^^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:397:5
+  --> $DIR/subdiagnostic-derive.rs:395:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:394:5
+  --> $DIR/subdiagnostic-derive.rs:392:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
 error: the `#[applicability]` attribute can only be applied to fields of type `Applicability`
-  --> $DIR/subdiagnostic-derive.rs:408:5
+  --> $DIR/subdiagnostic-derive.rs:405:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:403:1
+error: suggestion without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:418:1
    |
-LL | / #[suggestion(parser::add_paren, code = "...")]
-LL | |
-LL | | struct AL {
-LL | |     #[primary_span]
-...  |
-LL | |     applicability: Span,
-LL | | }
-   | |_^
+LL | #[suggestion(parser::add_paren)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: invalid applicability
+  --> $DIR/subdiagnostic-derive.rs:428:46
+   |
+LL | #[suggestion(parser::add_paren, code ="...", applicability = "foo")]
+   |                                              ^^^^^^^^^^^^^^^^^^^^^
 
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:414:1
+error: suggestion without `#[primary_span]` field
+  --> $DIR/subdiagnostic-derive.rs:446:1
    |
 LL | / #[suggestion(parser::add_paren, code = "...")]
 LL | |
-LL | | struct AM {
-LL | |     #[primary_span]
-LL | |     span: Span,
+LL | | struct AR {
+LL | |     var: String,
 LL | | }
    | |_^
 
-error: suggestion without `code = "..."`
-  --> $DIR/subdiagnostic-derive.rs:422:1
+error: unsupported type attribute for subdiagnostic enum
+  --> $DIR/subdiagnostic-derive.rs:460:1
+   |
+LL | #[label]
+   | ^^^^^^^^
+
+error: `var` doesn't refer to a field on this type
+  --> $DIR/subdiagnostic-derive.rs:480:39
+   |
+LL | #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
+   |                                       ^^^^^^^
+
+error: `var` doesn't refer to a field on this type
+  --> $DIR/subdiagnostic-derive.rs:499:43
+   |
+LL |     #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
+   |                                           ^^^^^^^
+
+error: `#[suggestion_part]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:523:5
+   |
+LL |     #[suggestion_part]
+   |     ^^^^^^^^^^^^^^^^^^
+   |
+   = help: `#[suggestion_part(...)]` is only valid in multipart suggestions, use `#[primary_span]` instead
+
+error: `#[suggestion_part(...)]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:526:5
+   |
+LL |     #[suggestion_part(code = "...")]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-LL | / #[suggestion(parser::add_paren)]
+   = help: `#[suggestion_part(...)]` is only valid in multipart suggestions
+
+error: suggestion without `#[primary_span]` field
+  --> $DIR/subdiagnostic-derive.rs:520:1
+   |
+LL | / #[suggestion(parser::add_paren, code = "...")]
 LL | |
-LL | | struct AN {
-LL | |     #[primary_span]
+LL | | struct BA {
+LL | |     #[suggestion_part]
 ...  |
-LL | |     applicability: Applicability,
+LL | |     var: String,
 LL | | }
    | |_^
 
-error: invalid applicability
-  --> $DIR/subdiagnostic-derive.rs:432:46
+error: `code` is not a valid nested attribute of a `multipart_suggestion` attribute
+  --> $DIR/subdiagnostic-derive.rs:535:43
    |
-LL | #[suggestion(parser::add_paren, code ="...", applicability = "foo")]
-   |                                              ^^^^^^^^^^^^^^^^^^^^^
+LL | #[multipart_suggestion(parser::add_paren, code = "...", applicability = "machine-applicable")]
+   |                                           ^^^^^^^^^^^^
 
-error: suggestion without `applicability`
-  --> $DIR/subdiagnostic-derive.rs:450:1
+error: multipart suggestion without any `#[suggestion_part(...)]` fields
+  --> $DIR/subdiagnostic-derive.rs:535:1
    |
-LL | / #[suggestion(parser::add_paren, code = "...")]
+LL | / #[multipart_suggestion(parser::add_paren, code = "...", applicability = "machine-applicable")]
 LL | |
 LL | |
-LL | | struct AR {
+LL | | struct BBa {
 LL | |     var: String,
 LL | | }
    | |_^
 
-error: suggestion without `#[primary_span]` field
-  --> $DIR/subdiagnostic-derive.rs:450:1
+error: `#[suggestion_part(...)]` attribute without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:545:5
    |
-LL | / #[suggestion(parser::add_paren, code = "...")]
+LL |     #[suggestion_part]
+   |     ^^^^^^^^^^^^^^^^^^
+
+error: `#[suggestion_part(...)]` attribute without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:553:5
+   |
+LL |     #[suggestion_part()]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: `#[primary_span]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:562:5
+   |
+LL |     #[primary_span]
+   |     ^^^^^^^^^^^^^^^
+   |
+   = help: multipart suggestions use one or more `#[suggestion_part]`s rather than one `#[primary_span]`
+
+error: multipart suggestion without any `#[suggestion_part(...)]` fields
+  --> $DIR/subdiagnostic-derive.rs:559:1
+   |
+LL | / #[multipart_suggestion(parser::add_paren)]
 LL | |
+LL | | struct BC {
+LL | |     #[primary_span]
 LL | |
-LL | | struct AR {
-LL | |     var: String,
+LL | |     span: Span,
 LL | | }
    | |_^
 
-error: unsupported type attribute for subdiagnostic enum
-  --> $DIR/subdiagnostic-derive.rs:465:1
+error: `#[suggestion_part(...)]` attribute without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:570:5
    |
-LL | #[label]
-   | ^^^^^^^^
+LL |     #[suggestion_part]
+   |     ^^^^^^^^^^^^^^^^^^
 
-error: `var` doesn't refer to a field on this type
-  --> $DIR/subdiagnostic-derive.rs:485:39
+error: `#[suggestion_part(...)]` attribute without `code = "..."`
+  --> $DIR/subdiagnostic-derive.rs:573:5
    |
-LL | #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
-   |                                       ^^^^^^^
+LL |     #[suggestion_part()]
+   |     ^^^^^^^^^^^^^^^^^^^^
 
-error: `var` doesn't refer to a field on this type
-  --> $DIR/subdiagnostic-derive.rs:504:43
+error: `#[suggestion_part(foo = ...)]` is not a valid attribute
+  --> $DIR/subdiagnostic-derive.rs:576:23
    |
-LL |     #[suggestion(parser::add_paren, code ="{var}", applicability = "machine-applicable")]
-   |                                           ^^^^^^^
+LL |     #[suggestion_part(foo = "bar")]
+   |                       ^^^^^^^^^^^
+   |
+   = help: `code` is the only valid nested attribute
+
+error: the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
+  --> $DIR/subdiagnostic-derive.rs:579:5
+   |
+LL |     #[suggestion_part(code = "...")]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
+  --> $DIR/subdiagnostic-derive.rs:582:5
+   |
+LL |     #[suggestion_part()]
+   |     ^^^^^^^^^^^^^^^^^^^^
+
+error: specified multiple times
+  --> $DIR/subdiagnostic-derive.rs:590:37
+   |
+LL |     #[suggestion_part(code = "...", code = ",,,")]
+   |                                     ^^^^^^^^^^^^
+   |
+note: previously specified here
+  --> $DIR/subdiagnostic-derive.rs:590:23
+   |
+LL |     #[suggestion_part(code = "...", code = ",,,")]
+   |                       ^^^^^^^^^^^^
+
+error: specified multiple times
+  --> $DIR/subdiagnostic-derive.rs:620:5
+   |
+LL |     #[applicability]
+   |     ^^^^^^^^^^^^^^^^
+   |
+note: previously specified here
+  --> $DIR/subdiagnostic-derive.rs:617:43
+   |
+LL | #[multipart_suggestion(parser::add_paren, applicability = "machine-applicable")]
+   |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: cannot find attribute `foo` in this scope
   --> $DIR/subdiagnostic-derive.rs:63:3
@@ -395,6 +475,6 @@ error[E0425]: cannot find value `slug` in module `rustc_errors::fluent`
 LL | #[label(slug)]
    |         ^^^^ not found in `rustc_errors::fluent`
 
-error: aborting due to 52 previous errors
+error: aborting due to 64 previous errors
 
 For more information about this error, try `rustc --explain E0425`.
diff --git a/src/test/ui/borrowck/index-mut-help.rs b/src/test/ui/borrowck/index-mut-help.rs
index d57ef975d9634..35266e113a6de 100644
--- a/src/test/ui/borrowck/index-mut-help.rs
+++ b/src/test/ui/borrowck/index-mut-help.rs
@@ -1,10 +1,9 @@
 // When mutably indexing a type that implements `Index` but not `IndexMut`, a
 // special 'help' message is added to the output.
+use std::collections::HashMap;
 
 
 fn main() {
-    use std::collections::HashMap;
-
     let mut map = HashMap::new();
     map.insert("peter", "23".to_string());
 
diff --git a/src/test/ui/borrowck/index-mut-help.stderr b/src/test/ui/borrowck/index-mut-help.stderr
index 0ce60e3eb1db8..f42d7e0155433 100644
--- a/src/test/ui/borrowck/index-mut-help.stderr
+++ b/src/test/ui/borrowck/index-mut-help.stderr
@@ -1,23 +1,33 @@
 error[E0596]: cannot borrow data in an index of `HashMap<&str, String>` as mutable
-  --> $DIR/index-mut-help.rs:11:5
+  --> $DIR/index-mut-help.rs:10:5
    |
 LL |     map["peter"].clear();
    |     ^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<&str, String>`
-   = help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `HashMap<&str, String>` use `.get_mut()`
+   |
+LL |     map.get_mut("peter").map(|val| val.clear());
+   |        ~~~~~~~~~       ~~~~~~~~~~~~~~~        +
 
 error[E0594]: cannot assign to data in an index of `HashMap<&str, String>`
-  --> $DIR/index-mut-help.rs:12:5
+  --> $DIR/index-mut-help.rs:11:5
    |
 LL |     map["peter"] = "0".to_string();
    |     ^^^^^^^^^^^^ cannot assign
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<&str, String>`
-   = help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API
+   |
+LL |     map.insert("peter", "0".to_string());
+   |        ~~~~~~~~       ~                +
+LL |     map.get_mut("peter").map(|val| { *val = "0".to_string(); });
+   |        ~~~~~~~~~       ~~~~~~~~~~~~~~~~~~                  ++++
+LL |     let val = map.entry("peter").or_insert("0".to_string());
+   |     +++++++++    ~~~~~~~       ~~~~~~~~~~~~               +
 
 error[E0596]: cannot borrow data in an index of `HashMap<&str, String>` as mutable
-  --> $DIR/index-mut-help.rs:13:13
+  --> $DIR/index-mut-help.rs:12:13
    |
 LL |     let _ = &mut map["peter"];
    |             ^^^^^^^^^^^^^^^^^ cannot borrow as mutable
diff --git a/src/test/ui/btreemap/btreemap-index-mut.stderr b/src/test/ui/btreemap/btreemap-index-mut.stderr
index 260f710007426..26f2a4c4b2914 100644
--- a/src/test/ui/btreemap/btreemap-index-mut.stderr
+++ b/src/test/ui/btreemap/btreemap-index-mut.stderr
@@ -5,7 +5,14 @@ LL |     map[&0] = 1;
    |     ^^^^^^^^^^^ cannot assign
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `BTreeMap<u32, u32>`
-   = help: to modify a `BTreeMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `BTreeMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
+   |
+LL |     map.insert(&0, 1);
+   |        ~~~~~~~~  ~  +
+LL |     map.get_mut(&0).map(|val| { *val = 1; });
+   |        ~~~~~~~~~  ~~~~~~~~~~~~~~~~~~    ++++
+LL |     let val = map.entry(&0).or_insert(1);
+   |     +++++++++    ~~~~~~~  ~~~~~~~~~~~~ +
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/cfg/future-compat-crate-attributes-using-cfg_attr.rs b/src/test/ui/cfg/future-compat-crate-attributes-using-cfg_attr.rs
index 6cb2ff9d8136b..1f23dadc43226 100644
--- a/src/test/ui/cfg/future-compat-crate-attributes-using-cfg_attr.rs
+++ b/src/test/ui/cfg/future-compat-crate-attributes-using-cfg_attr.rs
@@ -1,7 +1,6 @@
 // check-fail
 // compile-flags:--cfg foo
 
-#![deny(warnings)]
 #![cfg_attr(foo, crate_type="bin")]
 //~^ERROR `crate_type` within
 //~| WARN this was previously accepted
diff --git a/src/test/ui/cfg/future-compat-crate-attributes-using-cfg_attr.stderr b/src/test/ui/cfg/future-compat-crate-attributes-using-cfg_attr.stderr
index 5609f8e9d9f36..b52535ffdbab2 100644
--- a/src/test/ui/cfg/future-compat-crate-attributes-using-cfg_attr.stderr
+++ b/src/test/ui/cfg/future-compat-crate-attributes-using-cfg_attr.stderr
@@ -1,20 +1,15 @@
 error: `crate_type` within an `#![cfg_attr] attribute is deprecated`
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:5:18
+  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:4:18
    |
 LL | #![cfg_attr(foo, crate_type="bin")]
    |                  ^^^^^^^^^^^^^^^^
    |
-note: the lint level is defined here
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:4:9
-   |
-LL | #![deny(warnings)]
-   |         ^^^^^^^^
-   = note: `#[deny(deprecated_cfg_attr_crate_type_name)]` implied by `#[deny(warnings)]`
+   = note: `#[deny(deprecated_cfg_attr_crate_type_name)]` on by default
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #91632 <https://github.com/rust-lang/rust/issues/91632>
 
 error: `crate_name` within an `#![cfg_attr] attribute is deprecated`
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:10:18
+  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:9:18
    |
 LL | #![cfg_attr(foo, crate_name="bar")]
    |                  ^^^^^^^^^^^^^^^^
@@ -23,7 +18,7 @@ LL | #![cfg_attr(foo, crate_name="bar")]
    = note: for more information, see issue #91632 <https://github.com/rust-lang/rust/issues/91632>
 
 error: `crate_type` within an `#![cfg_attr] attribute is deprecated`
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:5:18
+  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:4:18
    |
 LL | #![cfg_attr(foo, crate_type="bin")]
    |                  ^^^^^^^^^^^^^^^^
@@ -32,7 +27,7 @@ LL | #![cfg_attr(foo, crate_type="bin")]
    = note: for more information, see issue #91632 <https://github.com/rust-lang/rust/issues/91632>
 
 error: `crate_name` within an `#![cfg_attr] attribute is deprecated`
-  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:10:18
+  --> $DIR/future-compat-crate-attributes-using-cfg_attr.rs:9:18
    |
 LL | #![cfg_attr(foo, crate_name="bar")]
    |                  ^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/consts/const-eval/issue-91827-extern-types.rs b/src/test/ui/consts/const-eval/issue-91827-extern-types.rs
index e1f5e8ae1453c..43c99799f7704 100644
--- a/src/test/ui/consts/const-eval/issue-91827-extern-types.rs
+++ b/src/test/ui/consts/const-eval/issue-91827-extern-types.rs
@@ -3,7 +3,6 @@
 // Test that we can handle unsized types with an extern type tail part.
 // Regression test for issue #91827.
 
-#![feature(const_ptr_offset_from)]
 #![feature(extern_types)]
 
 use std::ptr::addr_of;
diff --git a/src/test/ui/consts/offset.rs b/src/test/ui/consts/offset.rs
index f9ddda554fcf0..b2c663fe617a4 100644
--- a/src/test/ui/consts/offset.rs
+++ b/src/test/ui/consts/offset.rs
@@ -1,5 +1,4 @@
 // run-pass
-#![feature(const_ptr_offset_from)]
 use std::ptr;
 
 #[repr(C)]
diff --git a/src/test/ui/consts/offset_from.rs b/src/test/ui/consts/offset_from.rs
index b53718316f3b5..465147041d966 100644
--- a/src/test/ui/consts/offset_from.rs
+++ b/src/test/ui/consts/offset_from.rs
@@ -1,6 +1,5 @@
 // run-pass
 
-#![feature(const_ptr_offset_from)]
 #![feature(const_ptr_sub_ptr)]
 #![feature(ptr_sub_ptr)]
 
diff --git a/src/test/ui/consts/offset_from_ub.rs b/src/test/ui/consts/offset_from_ub.rs
index 1f29a690550bc..51163e650d6aa 100644
--- a/src/test/ui/consts/offset_from_ub.rs
+++ b/src/test/ui/consts/offset_from_ub.rs
@@ -1,4 +1,4 @@
-#![feature(const_ptr_offset_from)]
+#![feature(const_ptr_sub_ptr)]
 #![feature(core_intrinsics)]
 
 use std::intrinsics::{ptr_offset_from, ptr_offset_from_unsigned};
diff --git a/src/test/ui/hashmap/hashmap-index-mut.stderr b/src/test/ui/hashmap/hashmap-index-mut.stderr
index c72b380f4666d..c1948ab627149 100644
--- a/src/test/ui/hashmap/hashmap-index-mut.stderr
+++ b/src/test/ui/hashmap/hashmap-index-mut.stderr
@@ -5,7 +5,14 @@ LL |     map[&0] = 1;
    |     ^^^^^^^^^^^ cannot assign
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<u32, u32>`
-   = help: to modify a `HashMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `HashMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
+   |
+LL |     map.insert(&0, 1);
+   |        ~~~~~~~~  ~  +
+LL |     map.get_mut(&0).map(|val| { *val = 1; });
+   |        ~~~~~~~~~  ~~~~~~~~~~~~~~~~~~    ++++
+LL |     let val = map.entry(&0).or_insert(1);
+   |     +++++++++    ~~~~~~~  ~~~~~~~~~~~~ +
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-41726.stderr b/src/test/ui/issues/issue-41726.stderr
index 9c70ab7d9711d..b05c1fb14efc6 100644
--- a/src/test/ui/issues/issue-41726.stderr
+++ b/src/test/ui/issues/issue-41726.stderr
@@ -5,7 +5,10 @@ LL |         things[src.as_str()].sort();
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<String, Vec<String>>`
-   = help: to modify a `HashMap<String, Vec<String>>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `HashMap<String, Vec<String>>` use `.get_mut()`
+   |
+LL |         things.get_mut(src.as_str()).map(|val| val.sort());
+   |               ~~~~~~~~~            ~~~~~~~~~~~~~~~       +
 
 error: aborting due to previous error
 
diff --git a/src/tools/tidy/src/error_codes_check.rs b/src/tools/tidy/src/error_codes_check.rs
index f0054a1c1c9bb..0a226443e01ca 100644
--- a/src/tools/tidy/src/error_codes_check.rs
+++ b/src/tools/tidy/src/error_codes_check.rs
@@ -217,7 +217,7 @@ pub fn check(paths: &[&Path], bad: &mut bool) {
     println!("Checking which error codes lack tests...");
 
     for path in paths {
-        super::walk(path, &mut |path| super::filter_dirs(path), &mut |entry, contents| {
+        super::walk(path, &mut super::filter_dirs, &mut |entry, contents| {
             let file_name = entry.file_name();
             let entry_path = entry.path();
 
diff --git a/src/tools/unicode-table-generator/src/main.rs b/src/tools/unicode-table-generator/src/main.rs
index a3327a3c2ffd9..2fe578acd90e7 100644
--- a/src/tools/unicode-table-generator/src/main.rs
+++ b/src/tools/unicode-table-generator/src/main.rs
@@ -221,7 +221,7 @@ fn main() {
     let write_location = std::env::args().nth(1).unwrap_or_else(|| {
         eprintln!("Must provide path to write unicode tables to");
         eprintln!(
-            "e.g. {} library/core/unicode/unicode_data.rs",
+            "e.g. {} library/core/src/unicode/unicode_data.rs",
             std::env::args().next().unwrap_or_default()
         );
         std::process::exit(1);
diff --git a/src/tools/unicode-table-generator/src/unicode_download.rs b/src/tools/unicode-table-generator/src/unicode_download.rs
index 9b2e0a25891c7..714bb53382e70 100644
--- a/src/tools/unicode-table-generator/src/unicode_download.rs
+++ b/src/tools/unicode-table-generator/src/unicode_download.rs
@@ -1,6 +1,6 @@
 use crate::UNICODE_DIRECTORY;
 use std::path::Path;
-use std::process::Command;
+use std::process::{Command, Output};
 
 static URL_PREFIX: &str = "https://www.unicode.org/Public/UCD/latest/ucd/";
 
@@ -9,6 +9,18 @@ static README: &str = "ReadMe.txt";
 static RESOURCES: &[&str] =
     &["DerivedCoreProperties.txt", "PropList.txt", "UnicodeData.txt", "SpecialCasing.txt"];
 
+#[track_caller]
+fn fetch(url: &str) -> Output {
+    let output = Command::new("curl").arg(URL_PREFIX.to_owned() + url).output().unwrap();
+    if !output.status.success() {
+        panic!(
+            "Failed to run curl to fetch {url}: stderr: {}",
+            String::from_utf8_lossy(&output.stderr)
+        );
+    }
+    output
+}
+
 pub fn fetch_latest() {
     let directory = Path::new(UNICODE_DIRECTORY);
     if directory.exists() {
@@ -20,27 +32,14 @@ pub fn fetch_latest() {
     if let Err(e) = std::fs::create_dir_all(directory) {
         panic!("Failed to create {UNICODE_DIRECTORY:?}: {e}");
     }
-    let output = Command::new("curl").arg(URL_PREFIX.to_owned() + README).output().unwrap();
-    if !output.status.success() {
-        panic!(
-            "Failed to run curl to fetch readme: stderr: {}",
-            String::from_utf8_lossy(&output.stderr)
-        );
-    }
+    let output = fetch(README);
     let current = std::fs::read_to_string(directory.join(README)).unwrap_or_default();
     if current.as_bytes() != &output.stdout[..] {
         std::fs::write(directory.join(README), output.stdout).unwrap();
     }
 
     for resource in RESOURCES {
-        let output = Command::new("curl").arg(URL_PREFIX.to_owned() + resource).output().unwrap();
-        if !output.status.success() {
-            panic!(
-                "Failed to run curl to fetch {}: stderr: {}",
-                resource,
-                String::from_utf8_lossy(&output.stderr)
-            );
-        }
+        let output = fetch(resource);
         std::fs::write(directory.join(resource), output.stdout).unwrap();
     }
 }