Rollup merge of #121382 - nnethercote:rework-untranslatable_diagnostic-lint, r=davidtwco

Rework `untranslatable_diagnostic` lint

Currently it only checks calls to functions marked with `#[rustc_lint_diagnostics]`. This PR changes it to check calls to any function with an `impl Into<{D,Subd}iagnosticMessage>` parameter. This greatly improves its coverage and doesn't rely on people remembering to add `#[rustc_lint_diagnostics]`. It also lets us add `#[rustc_lint_diagnostics]` to a number of functions that don't have an `impl Into<{D,Subd}iagnosticMessage>`, such as `Diag::span`.

r? ``@davidtwco``

2 files changed, 55 insertions, 16 deletions

diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index 5390dda9b21..c186d5b284f 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -598,6 +598,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     ///
     /// In the meantime, though, callsites are required to deal with the "bug"
     /// locally in whichever way makes the most sense.
+    #[rustc_lint_diagnostics]
     #[track_caller]
     pub fn downgrade_to_delayed_bug(&mut self) {
         assert!(
@@ -631,6 +632,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     with_fn! { with_span_labels,
     /// Labels all the given spans with the provided label.
     /// See [`Self::span_label()`] for more information.
+    #[rustc_lint_diagnostics]
     pub fn span_labels(&mut self, spans: impl IntoIterator<Item = Span>, label: &str) -> &mut Self {
         for span in spans {
             self.span_label(span, label.to_string());
@@ -638,6 +640,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     } }
 
+    #[rustc_lint_diagnostics]
     pub fn replace_span_with(&mut self, after: Span, keep_label: bool) -> &mut Self {
         let before = self.span.clone();
         self.span(after);
@@ -653,6 +656,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     }
 
+    #[rustc_lint_diagnostics]
     pub fn note_expected_found(
         &mut self,
         expected_label: &dyn fmt::Display,
@@ -663,6 +667,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self.note_expected_found_extra(expected_label, expected, found_label, found, &"", &"")
     }
 
+    #[rustc_lint_diagnostics]
     pub fn note_expected_found_extra(
         &mut self,
         expected_label: &dyn fmt::Display,
@@ -705,6 +710,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     }
 
+    #[rustc_lint_diagnostics]
     pub fn note_trait_signature(&mut self, name: Symbol, signature: String) -> &mut Self {
         self.highlighted_note(vec![
             StringPart::normal(format!("`{name}` from trait: `")),
@@ -722,12 +728,14 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     } }
 
+    #[rustc_lint_diagnostics]
     fn highlighted_note(&mut self, msg: Vec<StringPart>) -> &mut Self {
         self.sub_with_highlights(Level::Note, msg, MultiSpan::new());
         self
     }
 
     /// This is like [`Diag::note()`], but it's only printed once.
+    #[rustc_lint_diagnostics]
     pub fn note_once(&mut self, msg: impl Into<SubdiagMessage>) -> &mut Self {
         self.sub(Level::OnceNote, msg, MultiSpan::new());
         self
@@ -748,6 +756,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
 
     /// Prints the span with a note above it.
     /// This is like [`Diag::note_once()`], but it gets its own span.
+    #[rustc_lint_diagnostics]
     pub fn span_note_once<S: Into<MultiSpan>>(
         &mut self,
         sp: S,
@@ -786,12 +795,14 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     } }
 
     /// This is like [`Diag::help()`], but it's only printed once.
+    #[rustc_lint_diagnostics]
     pub fn help_once(&mut self, msg: impl Into<SubdiagMessage>) -> &mut Self {
         self.sub(Level::OnceHelp, msg, MultiSpan::new());
         self
     }
 
     /// Add a help message attached to this diagnostic with a customizable highlighted message.
+    #[rustc_lint_diagnostics]
     pub fn highlighted_help(&mut self, msg: Vec<StringPart>) -> &mut Self {
         self.sub_with_highlights(Level::Help, msg, MultiSpan::new());
         self
@@ -812,12 +823,14 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     /// Disallow attaching suggestions this diagnostic.
     /// Any suggestions attached e.g. with the `span_suggestion_*` methods
     /// (before and after the call to `disable_suggestions`) will be ignored.
+    #[rustc_lint_diagnostics]
     pub fn disable_suggestions(&mut self) -> &mut Self {
         self.suggestions = Err(SuggestionsDisabled);
         self
     }
 
     /// Helper for pushing to `self.suggestions`, if available (not disable).
+    #[rustc_lint_diagnostics]
     fn push_suggestion(&mut self, suggestion: CodeSuggestion) {
         for subst in &suggestion.substitutions {
             for part in &subst.parts {
@@ -838,6 +851,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     with_fn! { with_multipart_suggestion,
     /// Show a suggestion that has multiple parts to it.
     /// In other words, multiple changes need to be applied as part of this suggestion.
+    #[rustc_lint_diagnostics]
     pub fn multipart_suggestion(
         &mut self,
         msg: impl Into<SubdiagMessage>,
@@ -854,6 +868,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
 
     /// Show a suggestion that has multiple parts to it, always as it's own subdiagnostic.
     /// In other words, multiple changes need to be applied as part of this suggestion.
+    #[rustc_lint_diagnostics]
     pub fn multipart_suggestion_verbose(
         &mut self,
         msg: impl Into<SubdiagMessage>,
@@ -869,6 +884,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     }
 
     /// [`Diag::multipart_suggestion()`] but you can set the [`SuggestionStyle`].
+    #[rustc_lint_diagnostics]
     pub fn multipart_suggestion_with_style(
         &mut self,
         msg: impl Into<SubdiagMessage>,
@@ -911,6 +927,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     /// be from the message, showing the span label inline would be visually unpleasant
     /// (marginally overlapping spans or multiline spans) and showing the snippet window wouldn't
     /// improve understandability.
+    #[rustc_lint_diagnostics]
     pub fn tool_only_multipart_suggestion(
         &mut self,
         msg: impl Into<SubdiagMessage>,
@@ -943,6 +960,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     /// * may contain a name of a function, variable, or type, but not whole expressions
     ///
     /// See `CodeSuggestion` for more information.
+    #[rustc_lint_diagnostics]
     pub fn span_suggestion(
         &mut self,
         sp: Span,
@@ -961,6 +979,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     } }
 
     /// [`Diag::span_suggestion()`] but you can set the [`SuggestionStyle`].
+    #[rustc_lint_diagnostics]
     pub fn span_suggestion_with_style(
         &mut self,
         sp: Span,
@@ -986,6 +1005,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
 
     with_fn! { with_span_suggestion_verbose,
     /// Always show the suggested change.
+    #[rustc_lint_diagnostics]
     pub fn span_suggestion_verbose(
         &mut self,
         sp: Span,
@@ -1006,6 +1026,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     with_fn! { with_span_suggestions,
     /// Prints out a message with multiple suggested edits of the code.
     /// See also [`Diag::span_suggestion()`].
+    #[rustc_lint_diagnostics]
     pub fn span_suggestions(
         &mut self,
         sp: Span,
@@ -1022,6 +1043,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         )
     } }
 
+    #[rustc_lint_diagnostics]
     pub fn span_suggestions_with_style(
         &mut self,
         sp: Span,
@@ -1052,6 +1074,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     /// Prints out a message with multiple suggested edits of the code, where each edit consists of
     /// multiple parts.
     /// See also [`Diag::multipart_suggestion()`].
+    #[rustc_lint_diagnostics]
     pub fn multipart_suggestions(
         &mut self,
         msg: impl Into<SubdiagMessage>,
@@ -1098,6 +1121,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     /// inline, it will only show the message and not the suggestion.
     ///
     /// See `CodeSuggestion` for more information.
+    #[rustc_lint_diagnostics]
     pub fn span_suggestion_short(
         &mut self,
         sp: Span,
@@ -1121,6 +1145,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     /// be from the message, showing the span label inline would be visually unpleasant
     /// (marginally overlapping spans or multiline spans) and showing the snippet window wouldn't
     /// improve understandability.
+    #[rustc_lint_diagnostics]
     pub fn span_suggestion_hidden(
         &mut self,
         sp: Span,
@@ -1165,6 +1190,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     /// [rustc_macros::Subdiagnostic]). Performs eager translation of any translatable messages
     /// used in the subdiagnostic, so suitable for use with repeated messages (i.e. re-use of
     /// interpolated variables).
+    #[rustc_lint_diagnostics]
     pub fn subdiagnostic(
         &mut self,
         dcx: &crate::DiagCtxt,
@@ -1180,6 +1206,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
 
     with_fn! { with_span,
     /// Add a span.
+    #[rustc_lint_diagnostics]
     pub fn span(&mut self, sp: impl Into<MultiSpan>) -> &mut Self {
         self.span = sp.into();
         if let Some(span) = self.span.primary_span() {
@@ -1188,6 +1215,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     } }
 
+    #[rustc_lint_diagnostics]
     pub fn is_lint(&mut self, name: String, has_future_breakage: bool) -> &mut Self {
         self.is_lint = Some(IsLint { name, has_future_breakage });
         self
@@ -1195,6 +1223,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
 
     with_fn! { with_code,
     /// Add an error code.
+    #[rustc_lint_diagnostics]
     pub fn code(&mut self, code: ErrCode) -> &mut Self {
         self.code = Some(code);
         self
@@ -1202,6 +1231,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
 
     with_fn! { with_primary_message,
     /// Add a primary message.
+    #[rustc_lint_diagnostics]
     pub fn primary_message(&mut self, msg: impl Into<DiagMessage>) -> &mut Self {
         self.messages[0] = (msg.into(), Style::NoStyle);
         self
@@ -1209,6 +1239,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
 
     with_fn! { with_arg,
     /// Add an argument.
+    #[rustc_lint_diagnostics]
     pub fn arg(
         &mut self,
         name: impl Into<DiagArgName>,
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 0caa8fa9e8a..76b44f73f47 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -1101,32 +1101,36 @@ impl DiagCtxt {
 // Functions beginning with `struct_`/`create_` create a diagnostic. Other
 // functions create and emit a diagnostic all in one go.
 impl DiagCtxt {
-    // No `#[rustc_lint_diagnostics]` because bug messages aren't user-facing.
+    // No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
+    // user-facing.
     #[track_caller]
-    pub fn struct_bug(&self, msg: impl Into<DiagMessage>) -> Diag<'_, BugAbort> {
-        Diag::new(self, Bug, msg)
+    pub fn struct_bug(&self, msg: impl Into<Cow<'static, str>>) -> Diag<'_, BugAbort> {
+        Diag::new(self, Bug, msg.into())
     }
 
-    // No `#[rustc_lint_diagnostics]` because bug messages aren't user-facing.
+    // No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
+    // user-facing.
     #[track_caller]
-    pub fn bug(&self, msg: impl Into<DiagMessage>) -> ! {
+    pub fn bug(&self, msg: impl Into<Cow<'static, str>>) -> ! {
         self.struct_bug(msg).emit()
     }
 
-    // No `#[rustc_lint_diagnostics]` because bug messages aren't user-facing.
+    // No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
+    // user-facing.
     #[track_caller]
     pub fn struct_span_bug(
         &self,
         span: impl Into<MultiSpan>,
-        msg: impl Into<DiagMessage>,
+        msg: impl Into<Cow<'static, str>>,
     ) -> Diag<'_, BugAbort> {
         self.struct_bug(msg).with_span(span)
     }
 
-    // No `#[rustc_lint_diagnostics]` because bug messages aren't user-facing.
+    // No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
+    // user-facing.
     #[track_caller]
-    pub fn span_bug(&self, span: impl Into<MultiSpan>, msg: impl Into<DiagMessage>) -> ! {
-        self.struct_span_bug(span, msg).emit()
+    pub fn span_bug(&self, span: impl Into<MultiSpan>, msg: impl Into<Cow<'static, str>>) -> ! {
+        self.struct_span_bug(span, msg.into()).emit()
     }
 
     #[track_caller]
@@ -1240,24 +1244,28 @@ impl DiagCtxt {
     }
 
     /// Ensures that an error is printed. See `Level::DelayedBug`.
-    // No `#[rustc_lint_diagnostics]` because bug messages aren't user-facing.
+    //
+    // No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
+    // user-facing.
     #[track_caller]
-    pub fn delayed_bug(&self, msg: impl Into<DiagMessage>) -> ErrorGuaranteed {
-        Diag::<ErrorGuaranteed>::new(self, DelayedBug, msg).emit()
+    pub fn delayed_bug(&self, msg: impl Into<Cow<'static, str>>) -> ErrorGuaranteed {
+        Diag::<ErrorGuaranteed>::new(self, DelayedBug, msg.into()).emit()
     }
 
     /// Ensures that an error is printed. See `Level::DelayedBug`.
     ///
     /// Note: this function used to be called `delay_span_bug`. It was renamed
     /// to match similar functions like `span_err`, `span_warn`, etc.
-    // No `#[rustc_lint_diagnostics]` because bug messages aren't user-facing.
+    //
+    // No `#[rustc_lint_diagnostics]` and no `impl Into<DiagMessage>` because bug messages aren't
+    // user-facing.
     #[track_caller]
     pub fn span_delayed_bug(
         &self,
         sp: impl Into<MultiSpan>,
-        msg: impl Into<DiagMessage>,
+        msg: impl Into<Cow<'static, str>>,
     ) -> ErrorGuaranteed {
-        Diag::<ErrorGuaranteed>::new(self, DelayedBug, msg).with_span(sp).emit()
+        Diag::<ErrorGuaranteed>::new(self, DelayedBug, msg.into()).with_span(sp).emit()
     }
 
     #[rustc_lint_diagnostics]