Add bullet points for error messages and use them in query cycle errors

compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs

@@ -116,13 +116,28 @@ fn annotation_level_for_level(level: Level) -> annotate_snippets::level::Level<'
         Level::Fatal | Level::Error => annotate_snippets::level::ERROR,
         Level::ForceWarning | Level::Warning => annotate_snippets::Level::WARNING,
         Level::Note | Level::OnceNote => annotate_snippets::Level::NOTE,
+        Level::BulletPoint => annotate_snippets::Level::NOTE.no_name(),
         Level::Help | Level::OnceHelp => annotate_snippets::Level::HELP,
         Level::FailureNote => annotate_snippets::Level::NOTE.no_name(),
         Level::Allow => panic!("Should not call with Allow"),
         Level::Expect => panic!("Should not call with Expect"),
     }
 }
 
+fn message_level_for_level(level: Level) -> annotate_snippets::level::Level<'static> {
+    match level {
+        Level::BulletPoint => annotate_snippets::Level::NOTE.no_name(),
+        _ => annotation_level_for_level(level),
+    }
+}
+
+fn format_message_for_level(level: Level, msg: Cow<'static, str>) -> Cow<'static, str> {
+    match level {
+        Level::BulletPoint => Cow::Owned(format!("   - {msg}")),
+        _ => msg,
+    }
+}
+
 impl AnnotateSnippetEmitter {
     pub fn new(dst: Destination) -> Self {
         Self {
@@ -174,11 +189,26 @@ impl AnnotateSnippetEmitter {
 
         // If we don't have span information, emit and exit
         let Some(sm) = self.sm.as_ref() else {
-            group = group.elements(children.iter().map(|c| {
-                let msg = format_diag_messages(&c.messages, args).to_string();
-                let level = annotation_level_for_level(c.level);
-                level.message(msg)
-            }));
+            for c in children {
+                let msg = format_message_for_level(
+                    c.level,
+                    Cow::Owned(format_diag_messages(&c.messages, args).to_string()),
+                );
+                let annotation_level = annotation_level_for_level(c.level);
+                let message_level = message_level_for_level(c.level);
+
+                if c.level == Level::BulletPoint
+                    && !c.span.has_primary_spans()
+                    && !c.span.has_span_labels()
+                {
+                    report.push(std::mem::replace(
+                        &mut group,
+                        Group::with_title(annotation_level.secondary_title(msg)),
+                    ));
+                } else {
+                    group = group.element(message_level.message(msg));
+                }
+            }
 
             report.push(group);
             if let Err(e) = emit_to_destination(
@@ -239,7 +269,8 @@ impl AnnotateSnippetEmitter {
         }
 
         for c in children {
-            let level = annotation_level_for_level(c.level);
+            let annotation_level = annotation_level_for_level(c.level);
+            let message_level = message_level_for_level(c.level);
 
             // If at least one portion of the message is styled, we need to
             // "pre-style" the message
@@ -248,16 +279,24 @@ impl AnnotateSnippetEmitter {
             } else {
                 format_diag_messages(&c.messages, args)
             };
+            let msg = format_message_for_level(c.level, msg);
 
             // This is a secondary message with no span info
             if !c.span.has_primary_spans() && !c.span.has_span_labels() {
-                group = group.element(level.clone().message(msg));
+                if c.level == Level::BulletPoint {
+                    report.push(std::mem::replace(
+                        &mut group,
+                        Group::with_title(annotation_level.secondary_title(msg)),
+                    ));
+                } else {
+                    group = group.element(message_level.message(msg));
+                }
                 continue;
             }
 
             report.push(std::mem::replace(
                 &mut group,
-                Group::with_title(level.clone().secondary_title(msg)),
+                Group::with_title(annotation_level.clone().secondary_title(msg)),
             ));
 
             let mut file_ann = collect_annotations(args, &c.span, sm);
@@ -286,7 +325,7 @@ impl AnnotateSnippetEmitter {
                         file_idx,
                         &mut report,
                         group,
-                        &level,
+                        &annotation_level,
                     );
                 }
             }

compiler/rustc_errors/src/diagnostic.rs

@@ -297,6 +297,7 @@ impl DiagInner {
             Level::ForceWarning
             | Level::Warning
             | Level::Note
+            | Level::BulletPoint
             | Level::OnceNote
             | Level::Help
             | Level::OnceHelp
@@ -688,6 +689,20 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     }
 
+    with_fn! { with_bullet_point,
+    /// Add a bullet point to this diagnostic.
+    pub fn bullet_point(&mut self, msg: impl Into<DiagMessage>) -> &mut Self {
+        self.sub(Level::BulletPoint, msg, MultiSpan::new());
+        self
+    } }
+
+    with_fn! { with_span_bullet_point,
+    /// Add a bullet point to this diagnostic.
+    pub fn span_bullet_point(&mut self, sp: impl Into<MultiSpan>, msg: impl Into<DiagMessage>) -> &mut Self {
+        self.sub(Level::BulletPoint, msg, sp.into());
+        self
+    } }
+
     pub fn highlighted_span_note(
         &mut self,
         span: impl Into<MultiSpan>,

compiler/rustc_errors/src/lib.rs

@@ -600,8 +600,8 @@ impl<'a> DiagCtxtHandle<'a> {
             DelayedBug => {
                 return self.inner.borrow_mut().emit_diagnostic(diag, self.tainted_with_errors);
             }
-            ForceWarning | Warning | Note | OnceNote | Help | OnceHelp | FailureNote | Allow
-            | Expect => None,
+            ForceWarning | Warning | Note | BulletPoint | OnceNote | Help | OnceHelp
+            | FailureNote | Allow | Expect => None,
         };
 
         // FIXME(Centril, #69537): Consider reintroducing panic on overwriting a stashed diagnostic
@@ -1261,7 +1261,7 @@ impl DiagCtxtInner {
                     return None;
                 }
             }
-            Note | Help | FailureNote => {}
+            Note | BulletPoint | Help | FailureNote => {}
             OnceNote | OnceHelp => panic!("bad level: {:?}", diagnostic.level),
             Allow => {
                 // Nothing emitted for allowed lints.
@@ -1531,6 +1531,7 @@ impl DelayedDiagInner {
 /// | ForceWarning | -        | ()                           | yes       | -   | lint-only
 /// | Warning      | -        | ()                           | yes       | yes | yes
 /// | Note         | -        | ()                           | rare      | yes | -
+/// | BulletPoint  | -        | ()                           | -         | yes | -
 /// | OnceNote     | -        | ()                           | -         | yes | lint-only
 /// | Help         | -        | ()                           | rare      | yes | -
 /// | OnceHelp     | -        | ()                           | -         | yes | lint-only
@@ -1574,6 +1575,9 @@ pub enum Level {
     /// A message giving additional context.
     Note,
 
+    /// A message rendered as a bullet point.
+    BulletPoint,
+
     /// A note that is only emitted once.
     OnceNote,
 
@@ -1611,7 +1615,7 @@ impl Level {
                     AnsiColor::Yellow.on_default()
                 }
             }
-            Note | OnceNote => AnsiColor::BrightGreen.on_default(),
+            Note | BulletPoint | OnceNote => AnsiColor::BrightGreen.on_default(),
             Help | OnceHelp => AnsiColor::BrightCyan.on_default(),
             FailureNote => anstyle::Style::new(),
             Allow | Expect => unreachable!(),
@@ -1624,6 +1628,7 @@ impl Level {
             Fatal | Error => "error",
             ForceWarning | Warning => "warning",
             Note | OnceNote => "note",
+            BulletPoint => "bullet-point",
             Help | OnceHelp => "help",
             FailureNote => "failure-note",
             Allow | Expect => unreachable!(),

compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs

@@ -237,6 +237,7 @@ impl DiagnosticDeriveVariantBuilder {
         let fn_ident = format_ident!("{}", subdiag);
         match subdiag {
             SubdiagnosticKind::Note
+            | SubdiagnosticKind::BulletPoint
             | SubdiagnosticKind::NoteOnce
             | SubdiagnosticKind::Help
             | SubdiagnosticKind::HelpOnce
@@ -362,6 +363,7 @@ impl DiagnosticDeriveVariantBuilder {
                 Ok(self.add_spanned_subdiagnostic(binding, &fn_ident, message, variant))
             }
             SubdiagnosticKind::Note
+            | SubdiagnosticKind::BulletPoint
             | SubdiagnosticKind::NoteOnce
             | SubdiagnosticKind::Help
             | SubdiagnosticKind::HelpOnce

compiler/rustc_macros/src/diagnostics/utils.rs

@@ -560,6 +560,8 @@ pub(super) enum SubdiagnosticKind {
     Label,
     /// `#[note(...)]`
     Note,
+    /// `#[bullet_point(...)]`
+    BulletPoint,
     /// `#[note_once(...)]`
     NoteOnce,
     /// `#[help(...)]`
@@ -612,6 +614,7 @@ impl SubdiagnosticVariant {
         let mut kind = match name {
             "label" => SubdiagnosticKind::Label,
             "note" => SubdiagnosticKind::Note,
+            "bullet_point" => SubdiagnosticKind::BulletPoint,
             "note_once" => SubdiagnosticKind::NoteOnce,
             "help" => SubdiagnosticKind::Help,
             "help_once" => SubdiagnosticKind::HelpOnce,
@@ -672,6 +675,7 @@ impl SubdiagnosticVariant {
                 match kind {
                     SubdiagnosticKind::Label
                     | SubdiagnosticKind::Note
+                    | SubdiagnosticKind::BulletPoint
                     | SubdiagnosticKind::NoteOnce
                     | SubdiagnosticKind::Help
                     | SubdiagnosticKind::HelpOnce
@@ -819,6 +823,7 @@ impl SubdiagnosticVariant {
             }
             SubdiagnosticKind::Label
             | SubdiagnosticKind::Note
+            | SubdiagnosticKind::BulletPoint
             | SubdiagnosticKind::NoteOnce
             | SubdiagnosticKind::Help
             | SubdiagnosticKind::HelpOnce
@@ -834,6 +839,7 @@ impl quote::IdentFragment for SubdiagnosticKind {
         match self {
             SubdiagnosticKind::Label => write!(f, "label"),
             SubdiagnosticKind::Note => write!(f, "note"),
+            SubdiagnosticKind::BulletPoint => write!(f, "bullet_point"),
             SubdiagnosticKind::NoteOnce => write!(f, "note_once"),
             SubdiagnosticKind::Help => write!(f, "help"),
             SubdiagnosticKind::HelpOnce => write!(f, "help_once"),

compiler/rustc_macros/src/lib.rs

@@ -184,6 +184,7 @@ decl_derive!(
         help,
         help_once,
         note,
+        bullet_point,
         note_once,
         warning,
         // field attributes
@@ -203,6 +204,7 @@ decl_derive!(
         help,
         help_once,
         note,
+        bullet_point,
         note_once,
         warning,
         subdiagnostic,

compiler/rustc_query_impl/src/error.rs

@@ -25,7 +25,7 @@ pub(crate) struct QueryOverflowNote {
 }
 
 #[derive(Subdiagnostic)]
-#[note("...which requires {$desc}...")]
+#[bullet_point("which requires {$desc}...")]
 pub(crate) struct CycleStack {
     #[primary_span]
     pub span: Span,
@@ -34,9 +34,9 @@ pub(crate) struct CycleStack {
 
 #[derive(Subdiagnostic)]
 pub(crate) enum StackCount {
-    #[note("...which immediately requires {$stack_bottom} again")]
+    #[bullet_point("which immediately requires {$stack_bottom} again")]
     Single { stack_bottom: String },
-    #[note("...which again requires {$stack_bottom}, completing the cycle")]
+    #[bullet_point("which again requires {$stack_bottom}, completing the cycle")]
     Multiple { stack_bottom: String },
 }
 

src/tools/compiletest/src/errors.rs

@@ -25,7 +25,7 @@ impl ErrorKind {
         match s {
             "help" => ErrorKind::Help,
             "error" | "error: internal compiler error" => ErrorKind::Error,
-            "note" | "failure-note" => ErrorKind::Note,
+            "note" | "failure-note" | "bullet-point" => ErrorKind::Note,
             "warning" => ErrorKind::Warning,
             _ => panic!("unexpected compiler diagnostic kind `{s}`"),
         }

tests/rustdoc-ui/private-type-cycle-dyn-110629.stderr

@@ -4,7 +4,8 @@ error[E0391]: cycle detected when expanding type alias `Bar`
 LL | type Bar<'a, 'b> = Box<dyn PartialEq<Bar<'a, 'b>>>;
    |                                      ^^^^^^^^^^^
    |
-   = note: ...which immediately requires expanding type alias `Bar` again
+   - which immediately requires expanding type alias `Bar` again
+   |
    = note: type aliases cannot be recursive
    = help: consider using a struct, enum, or union instead to break the cycle
    = help: see <https://doc.rust-lang.org/reference/types.html#recursive-types> for more information

tests/ui/associated-consts/defaults-cyclic-fail.stderr

@@ -4,22 +4,22 @@ error[E0391]: cycle detected when simplifying constant for the type system `Tr::
 LL |     const A: u8 = Self::B;
    |     ^^^^^^^^^^^
    |
-note: ...which requires const-evaluating + checking `Tr::A`...
+   - which requires const-evaluating + checking `Tr::A`...
   --> $DIR/defaults-cyclic-fail.rs:5:19
    |
 LL |     const A: u8 = Self::B;
    |                   ^^^^^^^
-note: ...which requires simplifying constant for the type system `Tr::B`...
+   - which requires simplifying constant for the type system `Tr::B`...
   --> $DIR/defaults-cyclic-fail.rs:8:5
    |
 LL |     const B: u8 = Self::A;
    |     ^^^^^^^^^^^
-note: ...which requires const-evaluating + checking `Tr::B`...
+   - which requires const-evaluating + checking `Tr::B`...
   --> $DIR/defaults-cyclic-fail.rs:8:19
    |
 LL |     const B: u8 = Self::A;
    |                   ^^^^^^^
-   = note: ...which again requires simplifying constant for the type system `Tr::A`, completing the cycle
+   - which again requires simplifying constant for the type system `Tr::A`, completing the cycle
 note: cycle used when optimizing promoted MIR for `main`
   --> $DIR/defaults-cyclic-fail.rs:16:16
    |

tests/ui/associated-consts/issue-24949-assoc-const-static-recursion-impl.stderr

@@ -4,22 +4,22 @@ error[E0391]: cycle detected when checking if `IMPL_REF_BAR` is a trivial const
 LL | const IMPL_REF_BAR: u32 = GlobalImplRef::BAR;
    | ^^^^^^^^^^^^^^^^^^^^^^^
    |
-note: ...which requires building MIR for `IMPL_REF_BAR`...
+   - which requires building MIR for `IMPL_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:7:1
    |
 LL | const IMPL_REF_BAR: u32 = GlobalImplRef::BAR;
    | ^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires checking if `<impl at $DIR/issue-24949-assoc-const-static-recursion-impl.rs:11:1: 11:19>::BAR` is a trivial const...
+   - which requires checking if `<impl at $DIR/issue-24949-assoc-const-static-recursion-impl.rs:11:1: 11:19>::BAR` is a trivial const...
   --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:12:5
    |
 LL |     const BAR: u32 = IMPL_REF_BAR;
    |     ^^^^^^^^^^^^^^
-note: ...which requires building MIR for `<impl at $DIR/issue-24949-assoc-const-static-recursion-impl.rs:11:1: 11:19>::BAR`...
+   - which requires building MIR for `<impl at $DIR/issue-24949-assoc-const-static-recursion-impl.rs:11:1: 11:19>::BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:12:5
    |
 LL |     const BAR: u32 = IMPL_REF_BAR;
    |     ^^^^^^^^^^^^^^
-   = note: ...which again requires checking if `IMPL_REF_BAR` is a trivial const, completing the cycle
+   - which again requires checking if `IMPL_REF_BAR` is a trivial const, completing the cycle
 note: cycle used when simplifying constant for the type system `IMPL_REF_BAR`
   --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:7:1
    |

tests/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait-default.stderr

@@ -4,32 +4,32 @@ error[E0391]: cycle detected when caching mir of `FooDefault::BAR` for CTFE
 LL |     const BAR: u32 = DEFAULT_REF_BAR;
    |     ^^^^^^^^^^^^^^
    |
-note: ...which requires elaborating drops for `FooDefault::BAR`...
+   - which requires elaborating drops for `FooDefault::BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:8:22
    |
 LL |     const BAR: u32 = DEFAULT_REF_BAR;
    |                      ^^^^^^^^^^^^^^^
-note: ...which requires simplifying constant for the type system `DEFAULT_REF_BAR`...
+   - which requires simplifying constant for the type system `DEFAULT_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:11:1
    |
 LL | const DEFAULT_REF_BAR: u32 = <GlobalDefaultRef>::BAR;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires const-evaluating + checking `DEFAULT_REF_BAR`...
+   - which requires const-evaluating + checking `DEFAULT_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:11:30
    |
 LL | const DEFAULT_REF_BAR: u32 = <GlobalDefaultRef>::BAR;
    |                              ^^^^^^^^^^^^^^^^^^^^^^^
-note: ...which requires simplifying constant for the type system `FooDefault::BAR`...
+   - which requires simplifying constant for the type system `FooDefault::BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:8:5
    |
 LL |     const BAR: u32 = DEFAULT_REF_BAR;
    |     ^^^^^^^^^^^^^^
-note: ...which requires const-evaluating + checking `FooDefault::BAR`...
+   - which requires const-evaluating + checking `FooDefault::BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:8:5
    |
 LL |     const BAR: u32 = DEFAULT_REF_BAR;
    |     ^^^^^^^^^^^^^^
-   = note: ...which again requires caching mir of `FooDefault::BAR` for CTFE, completing the cycle
+   - which again requires caching mir of `FooDefault::BAR` for CTFE, completing the cycle
 note: cycle used when const-evaluating + checking `FooDefault::BAR`
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:8:5
    |