Rollup of 5 pull requests

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -207,15 +207,29 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
     fn visit_foreign_item(&mut self, i: &'a ast::ForeignItem) {
         match i.kind {
             ast::ForeignItemKind::Fn(..) | ast::ForeignItemKind::Static(..) => {
-                let link_name = attr::first_attr_value_str_by_name(&i.attrs, sym::link_name);
-                let links_to_llvm = link_name.is_some_and(|val| val.as_str().starts_with("llvm."));
-                if links_to_llvm {
+                let symbol_name = if let Some(link_name) =
+                    attr::first_attr_value_str_by_name(&i.attrs, sym::link_name)
+                {
+                    link_name
+                } else {
+                    i.kind.ident().unwrap().name
+                };
+
+                let name = symbol_name.as_str();
+                if name.starts_with("llvm.") {
                     gate!(
                         self,
                         link_llvm_intrinsics,
                         i.span,
                         "linking to LLVM intrinsics is experimental"
                     );
+                } else if name.starts_with("__enzyme_") {
+                    gate!(
+                        self,
+                        link_enzyme_intrinsics,
+                        i.span,
+                        "linking to Enzyme intrinsics is experimental"
+                    );
                 }
             }
             ast::ForeignItemKind::TyAlias(..) => {

compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs

@@ -10,6 +10,7 @@ use std::fmt::Debug;
 use std::io;
 use std::io::Write;
 use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, Ordering};
 
 use annotate_snippets::renderer::DEFAULT_TERM_WIDTH;
 use annotate_snippets::{AnnotationKind, Group, Origin, Padding, Patch, Renderer, Snippet};
@@ -46,6 +47,9 @@ pub struct AnnotateSnippetEmitter {
     track_diagnostics: bool,
     terminal_url: TerminalUrl,
     theme: OutputTheme,
+    /// Whether we've already suggested installing `rust-src`. Shown at most once per compile.
+    #[setters(skip)]
+    rust_src_hint_shown: AtomicBool,
 }
 
 impl Debug for AnnotateSnippetEmitter {
@@ -147,6 +151,7 @@ impl AnnotateSnippetEmitter {
             track_diagnostics: false,
             terminal_url: TerminalUrl::No,
             theme: OutputTheme::Ascii,
+            rust_src_hint_shown: AtomicBool::new(false),
         }
     }
 
@@ -231,6 +236,7 @@ impl AnnotateSnippetEmitter {
                         group,
                         &annotation_level,
                     );
+                    self.maybe_suggest_rust_src(&file.name, sm, &mut group);
                     // If this is the last annotation for a file, and
                     // this is the last file, and the first child is a
                     // "secondary" message, we need to add padding
@@ -299,6 +305,7 @@ impl AnnotateSnippetEmitter {
                         group,
                         &level,
                     );
+                    self.maybe_suggest_rust_src(&file.name, sm, &mut group);
                 }
             }
         }
@@ -582,6 +589,29 @@ impl AnnotateSnippetEmitter {
         }
     }
 
+    /// If `file_name` is a remapped standard-library source (so its source isn't available
+    /// locally), append a one-time `help` telling the user to install `rust-src`. Shown at most
+    /// once per compile session (tracked via `self.rust_src_hint_shown`).
+    fn maybe_suggest_rust_src<'a>(
+        &self,
+        file_name: &FileName,
+        sm: &Arc<SourceMap>,
+        group: &mut Group<'a>,
+    ) {
+        if self.rust_src_hint_shown.load(Ordering::Relaxed)
+            || !sm.filename_for_diagnostics(file_name).starts_with("/rustc/")
+        {
+            return;
+        }
+        self.rust_src_hint_shown.store(true, Ordering::Relaxed);
+        // `Group::element` consumes `self`, so swap in a cheap placeholder to take ownership.
+        let owned = std::mem::replace(group, Group::with_level(annotate_snippets::Level::HELP));
+        *group = owned.element(annotate_snippets::Level::HELP.message(
+            "the source code for the standard library is not available; \
+             run `rustup component add rust-src` to make it available",
+        ));
+    }
+
     fn unannotated_messages<'a>(
         &self,
         annotations: Vec<Annotation>,

compiler/rustc_feature/src/unstable.rs

@@ -247,6 +247,8 @@ declare_features! (
     (internal, lang_items, "1.0.0", None),
     /// Allows `#[link(..., cfg(..))]`; perma-unstable per #37406
     (internal, link_cfg, "1.14.0", None),
+    /// Allows using `#[link_name="__enzyme_*"]`.
+    (internal, link_enzyme_intrinsics, "CURRENT_RUSTC_VERSION", None),
     /// Allows using `?Trait` trait bounds in more contexts.
     (internal, more_maybe_bounds, "1.82.0", None),
     /// Allow negative trait bounds. This is an internal-only feature for testing the trait solver!

compiler/rustc_span/src/lib.rs

@@ -564,6 +564,14 @@ impl<'a> FileNameDisplay<'a> {
             _ => Cow::from(self.to_string()),
         }
     }
+
+    /// Returns whether the displayed file name starts with `prefix`.
+    ///
+    /// Avoids allocating in the common case of a valid-UTF-8 path, where
+    /// `to_string_lossy` borrows rather than allocates.
+    pub fn starts_with(&self, prefix: &str) -> bool {
+        self.to_string_lossy().starts_with(prefix)
+    }
 }
 
 impl FileName {

compiler/rustc_span/src/symbol.rs

@@ -1204,6 +1204,7 @@ symbols! {
         link_args,
         link_cfg,
         link_dash_arg: "link-arg",
+        link_enzyme_intrinsics,
         link_llvm_intrinsics,
         link_name,
         link_ordinal,

src/bootstrap/mk/Makefile.in

@@ -112,9 +112,9 @@ TEST_SET2 := --skip=tests --skip=library --skip=tidyselftest
 
 # this intentionally doesn't use `$(BOOTSTRAP)` so we can test the shebang on Windows
 ci-msvc-py:
-	$(Q)$(CFG_SRC_DIR)/x.py test --stage 2 $(TEST_SET1) --skip=src/tools/linkchecker
+	$(Q)$(CFG_SRC_DIR)/x.py test --stage 2 $(TEST_SET1)
 ci-msvc-ps1:
-	$(Q)$(CFG_SRC_DIR)/x.ps1 test --stage 2 $(TEST_SET2) --skip=src/tools/linkchecker
+	$(Q)$(CFG_SRC_DIR)/x.ps1 test --stage 2 $(TEST_SET2)
 ci-msvc: ci-msvc-py ci-msvc-ps1
 
 ## MingW native builders

src/bootstrap/src/core/build_steps/doc.rs

@@ -1415,13 +1415,6 @@ impl CommandLineStep for RustcBook {
     /// in the "md-doc" directory in the build output directory. Then
     /// "rustbook" is used to convert it to HTML.
     fn run(self, builder: &Builder<'_>) {
-        // FIXME: Temporary workaround for https://github.com/rust-lang/rust/issues/158378
-        // Make sure this workaround doesn't break unit tests on the affected host.
-        if cfg!(not(test)) && self.target == "i686-pc-windows-msvc" {
-            eprintln!("WARNING: Skipping rustc book build to work around #158378");
-            return;
-        }
-
         let out_base = builder.out.join(self.target).join("md-doc").join("rustc");
         t!(fs::create_dir_all(&out_base));
         let out_listing = out_base.join("src/lints");

src/ci/github-actions/jobs.yml

@@ -811,7 +811,6 @@ auto:
         --host=
         --target=i686-pc-windows-msvc
         --enable-profiler
-        --disable-docs
       SCRIPT: python x.py dist bootstrap --include-default-paths
       CODEGEN_BACKENDS: llvm
     <<: *job-windows

src/tools/build-manifest/src/main.rs

@@ -26,7 +26,6 @@ static DOCS_FALLBACK: &[(&str, &str)] = &[
     ("-apple-", "aarch64-apple-darwin"),
     ("aarch64", "aarch64-unknown-linux-gnu"),
     ("arm-", "aarch64-unknown-linux-gnu"),
-    ("i686-pc-windows", "x86_64-pc-windows-msvc"),
     ("", "x86_64-unknown-linux-gnu"),
 ];
 

tests/ui/errors/suggest-rust-src.rs

@@ -0,0 +1,27 @@
+// When a diagnostic points into the standard library but its source isn't
+// available locally, rustc can't render the snippet. In that case it should
+// suggest installing the `rust-src` component. See #156402.
+//
+// We simulate the "std source unavailable" situation (as happens with a `rustup`
+// toolchain that doesn't have `rust-src` installed) by remapping the rust-src
+// base and disabling translation back to the local path.
+//@ compile-flags: -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no
+//
+// The line:col of the remapped std path is volatile, so normalise it. (The
+// `$SRC_DIR` normalisation doesn't kick in because the path is remapped.)
+//@ normalize-stderr: ".rs:\d+:\d+" -> ".rs:LL:COL"
+
+use std::thread;
+
+struct Worker {
+    thread: thread::JoinHandle<()>,
+}
+
+impl Drop for Worker {
+    fn drop(&mut self) {
+        self.thread.join().unwrap();
+        //~^ ERROR cannot move out of `self.thread` which is behind a mutable reference
+    }
+}
+
+fn main() {}

tests/ui/errors/suggest-rust-src.stderr

@@ -0,0 +1,15 @@
+error[E0507]: cannot move out of `self.thread` which is behind a mutable reference
+  --> $DIR/suggest-rust-src.rs:LL:COL
+   |
+LL |         self.thread.join().unwrap();
+   |         ^^^^^^^^^^^ ------ `self.thread` moved due to this method call
+   |         |
+   |         move occurs because `self.thread` has type `JoinHandle<()>`, which does not implement the `Copy` trait
+   |
+note: `JoinHandle::<T>::join` takes ownership of the receiver `self`, which moves `self.thread`
+  --> $SRC_DIR/std/src/thread/join_handle.rs:LL:COL
+   = help: the source code for the standard library is not available; run `rustup component add rust-src` to make it available
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0507`.

tests/ui/feature-gates/feature-gate-link-enzyme-intrinsics-enabled.rs

@@ -0,0 +1,18 @@
+//@ check-pass
+// gate-test-link_enzyme_intrinsics
+#![feature(link_enzyme_intrinsics)]
+
+unsafe extern "C" {
+    fn __enzyme_autodiff();
+    fn __enzyme_fwddiff();
+    fn __enzyme_augmentfwd();
+    fn __enzyme_reverse();
+    #[link_name = "__enzyme_autodiff"]
+    fn autodiff();
+
+    static __enzyme_dup: i32;
+    #[link_name = "__enzyme_dup"]
+    static ENZYME_DUP: i32;
+}
+
+fn main() {}

tests/ui/feature-gates/feature-gate-link-enzyme-intrinsics-no-gate.rs

@@ -0,0 +1,30 @@
+// gate-test-link_enzyme_intrinsics
+
+unsafe extern "C" {
+    fn __enzyme_autodiff();
+    //~^ ERROR linking to Enzyme intrinsics is experimental
+
+    fn __enzyme_fwddiff();
+    //~^ ERROR linking to Enzyme intrinsics is experimental
+
+    fn __enzyme_augmentfwd();
+    //~^ ERROR linking to Enzyme intrinsics is experimental
+
+    fn __enzyme_reverse();
+    //~^ ERROR linking to Enzyme intrinsics is experimental
+
+    #[link_name = "__enzyme_autodiff"]
+    fn autodiff();
+    //~^ ERROR linking to Enzyme intrinsics is experimental
+
+    static __enzyme_dup: i32;
+    //~^ ERROR linking to Enzyme intrinsics is experimental
+
+    #[link_name = "__enzyme_dup"]
+    static ENZYME_DUP: i32;
+    //~^ ERROR linking to Enzyme intrinsics is experimental
+
+    static enzyme_dup: i32;
+}
+
+fn main() {}

tests/ui/feature-gates/feature-gate-link-enzyme-intrinsics-no-gate.stderr

@@ -0,0 +1,66 @@
+error[E0658]: linking to Enzyme intrinsics is experimental
+  --> $DIR/feature-gate-link-enzyme-intrinsics-no-gate.rs:4:5
+   |
+LL |     fn __enzyme_autodiff();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(link_enzyme_intrinsics)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: linking to Enzyme intrinsics is experimental
+  --> $DIR/feature-gate-link-enzyme-intrinsics-no-gate.rs:7:5
+   |
+LL |     fn __enzyme_fwddiff();
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(link_enzyme_intrinsics)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: linking to Enzyme intrinsics is experimental
+  --> $DIR/feature-gate-link-enzyme-intrinsics-no-gate.rs:10:5
+   |
+LL |     fn __enzyme_augmentfwd();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(link_enzyme_intrinsics)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: linking to Enzyme intrinsics is experimental
+  --> $DIR/feature-gate-link-enzyme-intrinsics-no-gate.rs:13:5
+   |
+LL |     fn __enzyme_reverse();
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(link_enzyme_intrinsics)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: linking to Enzyme intrinsics is experimental
+  --> $DIR/feature-gate-link-enzyme-intrinsics-no-gate.rs:17:5
+   |
+LL |     fn autodiff();
+   |     ^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(link_enzyme_intrinsics)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: linking to Enzyme intrinsics is experimental
+  --> $DIR/feature-gate-link-enzyme-intrinsics-no-gate.rs:20:5
+   |
+LL |     static __enzyme_dup: i32;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(link_enzyme_intrinsics)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: linking to Enzyme intrinsics is experimental
+  --> $DIR/feature-gate-link-enzyme-intrinsics-no-gate.rs:24:5
+   |
+LL |     static ENZYME_DUP: i32;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(link_enzyme_intrinsics)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0658`.

tests/ui/higher-ranked/hr-fn-ptr-trait-impl-mismatch-29061.rs

@@ -0,0 +1,33 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/29061>.
+//!
+//! A trait implemented for a higher-ranked fn pointer is not implemented for a fn pointer
+//! with a specific lifetime, and vice versa. The errors now spell out which form the impl
+//! applies to instead of just saying the bound is unsatisfied.
+
+//@ edition: 2024
+
+#![allow(dead_code)]
+
+fn x(_: &()) {}
+
+trait HR {}
+impl HR for fn(&()) {}
+fn hr<T: HR>(_: T) {}
+
+trait NotHR {}
+impl<'a> NotHR for fn(&'a ()) {}
+fn not_hr<T: NotHR>(_: T) {}
+
+fn a<'a>() {
+    let not_hr_func: fn(&'a ()) = x;
+    let hr_func: fn(&()) = x;
+    let hr_func2: for<'b> fn(&'b ()) = x;
+    hr(not_hr_func);
+    //~^ ERROR implementation of `HR` is not general enough
+    not_hr(hr_func);
+    //~^ ERROR implementation of `NotHR` is not general enough
+    not_hr(hr_func2);
+    //~^ ERROR implementation of `NotHR` is not general enough
+}
+
+fn main() {}