lint: add diagnostic translation migration lints

Introduce allow-by-default lints for checking whether diagnostics are
written in `SessionDiagnostic`/`AddSubdiagnostic` impls and whether
diagnostics are translatable. These lints can be denied for modules once
they are fully migrated to impls and translation.

Signed-off-by: David Wood <david.wood@huawei.com>

Author: davidtwco

compiler/rustc_error_messages/src/lib.rs

@@ -1,6 +1,7 @@
 #![feature(let_chains)]
 #![feature(once_cell)]
 #![feature(path_try_exists)]
+#![feature(rustc_attrs)]
 #![feature(type_alias_impl_trait)]
 
 use fluent_bundle::FluentResource;
@@ -241,6 +242,7 @@ type FluentId = Cow<'static, str>;
 /// message so messages of this type must be combined with a `DiagnosticMessage` (using
 /// `DiagnosticMessage::with_subdiagnostic_message`) before rendering. However, subdiagnostics from
 /// the `SessionSubdiagnostic` derive refer to Fluent identifiers directly.
+#[rustc_diagnostic_item = "SubdiagnosticMessage"]
 pub enum SubdiagnosticMessage {
     /// Non-translatable diagnostic message.
     // FIXME(davidtwco): can a `Cow<'static, str>` be used here?
@@ -281,6 +283,7 @@ impl<S: Into<String>> From<S> for SubdiagnosticMessage {
 ///
 /// Intended to be removed once diagnostics are entirely translatable.
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
+#[rustc_diagnostic_item = "DiagnosticMessage"]
 pub enum DiagnosticMessage {
     /// Non-translatable diagnostic message.
     // FIXME(davidtwco): can a `Cow<'static, str>` be used here?

compiler/rustc_errors/src/diagnostic.rs

@@ -80,6 +80,7 @@ impl<'source> Into<FluentValue<'source>> for DiagnosticArgValue<'source> {
 
 /// Trait implemented by error types. This should not be implemented manually. Instead, use
 /// `#[derive(SessionSubdiagnostic)]` -- see [rustc_macros::SessionSubdiagnostic].
+#[rustc_diagnostic_item = "AddSubdiagnostic"]
 pub trait AddSubdiagnostic {
     /// Add a subdiagnostic to an existing diagnostic.
     fn add_to_diagnostic(self, diag: &mut Diagnostic);
@@ -283,6 +284,7 @@ impl Diagnostic {
     ///
     /// This span is *not* considered a ["primary span"][`MultiSpan`]; only
     /// the `Span` supplied when creating the diagnostic is primary.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_label(&mut self, span: Span, label: impl Into<SubdiagnosticMessage>) -> &mut Self {
         self.span.push_span_label(span, self.subdiagnostic_message_to_diagnostic_message(label));
         self
@@ -401,6 +403,7 @@ impl Diagnostic {
     }
 
     /// Add a note attached to this diagnostic.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn note(&mut self, msg: impl Into<SubdiagnosticMessage>) -> &mut Self {
         self.sub(Level::Note, msg, MultiSpan::new(), None);
         self
@@ -423,6 +426,7 @@ impl Diagnostic {
 
     /// Prints the span with a note above it.
     /// This is like [`Diagnostic::note()`], but it gets its own span.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_note<S: Into<MultiSpan>>(
         &mut self,
         sp: S,
@@ -444,13 +448,15 @@ impl Diagnostic {
     }
 
     /// Add a warning attached to this diagnostic.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn warn(&mut self, msg: impl Into<SubdiagnosticMessage>) -> &mut Self {
         self.sub(Level::Warning, msg, MultiSpan::new(), None);
         self
     }
 
     /// Prints the span with a warning above it.
     /// This is like [`Diagnostic::warn()`], but it gets its own span.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_warn<S: Into<MultiSpan>>(
         &mut self,
         sp: S,
@@ -461,6 +467,7 @@ impl Diagnostic {
     }
 
     /// Add a help message attached to this diagnostic.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn help(&mut self, msg: impl Into<SubdiagnosticMessage>) -> &mut Self {
         self.sub(Level::Help, msg, MultiSpan::new(), None);
         self
@@ -474,6 +481,7 @@ impl Diagnostic {
 
     /// Prints the span with some help above it.
     /// This is like [`Diagnostic::help()`], but it gets its own span.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_help<S: Into<MultiSpan>>(
         &mut self,
         sp: S,

compiler/rustc_errors/src/lib.rs

@@ -9,6 +9,7 @@
 #![feature(let_else)]
 #![feature(never_type)]
 #![feature(adt_const_params)]
+#![feature(rustc_attrs)]
 #![allow(incomplete_features)]
 #![allow(rustc::potential_query_instability)]
 
@@ -644,6 +645,7 @@ impl Handler {
     /// Attempting to `.emit()` the builder will only emit if either:
     /// * `can_emit_warnings` is `true`
     /// * `is_force_warn` was set in `DiagnosticId::Lint`
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_span_warn(
         &self,
         span: impl Into<MultiSpan>,
@@ -655,6 +657,7 @@ impl Handler {
     }
 
     /// Construct a builder at the `Allow` level at the given `span` and with the `msg`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_span_allow(
         &self,
         span: impl Into<MultiSpan>,
@@ -667,6 +670,7 @@ impl Handler {
 
     /// Construct a builder at the `Warning` level at the given `span` and with the `msg`.
     /// Also include a code.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_span_warn_with_code(
         &self,
         span: impl Into<MultiSpan>,
@@ -683,16 +687,19 @@ impl Handler {
     /// Attempting to `.emit()` the builder will only emit if either:
     /// * `can_emit_warnings` is `true`
     /// * `is_force_warn` was set in `DiagnosticId::Lint`
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_warn(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         DiagnosticBuilder::new(self, Level::Warning, msg)
     }
 
     /// Construct a builder at the `Allow` level with the `msg`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_allow(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         DiagnosticBuilder::new(self, Level::Allow, msg)
     }
 
     /// Construct a builder at the `Expect` level with the `msg`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_expect(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -702,6 +709,7 @@ impl Handler {
     }
 
     /// Construct a builder at the `Error` level at the given `span` and with the `msg`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_span_err(
         &self,
         span: impl Into<MultiSpan>,
@@ -713,6 +721,7 @@ impl Handler {
     }
 
     /// Construct a builder at the `Error` level at the given `span`, with the `msg`, and `code`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_span_err_with_code(
         &self,
         span: impl Into<MultiSpan>,
@@ -726,6 +735,7 @@ impl Handler {
 
     /// Construct a builder at the `Error` level with the `msg`.
     // FIXME: This method should be removed (every error should have an associated error code).
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_err(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -740,6 +750,7 @@ impl Handler {
     }
 
     /// Construct a builder at the `Error` level with the `msg` and the `code`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_err_with_code(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -751,6 +762,7 @@ impl Handler {
     }
 
     /// Construct a builder at the `Warn` level with the `msg` and the `code`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_warn_with_code(
         &self,
         msg: impl Into<DiagnosticMessage>,
@@ -762,6 +774,7 @@ impl Handler {
     }
 
     /// Construct a builder at the `Fatal` level at the given `span` and with the `msg`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_span_fatal(
         &self,
         span: impl Into<MultiSpan>,
@@ -773,6 +786,7 @@ impl Handler {
     }
 
     /// Construct a builder at the `Fatal` level at the given `span`, with the `msg`, and `code`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_span_fatal_with_code(
         &self,
         span: impl Into<MultiSpan>,
@@ -785,28 +799,33 @@ impl Handler {
     }
 
     /// Construct a builder at the `Error` level with the `msg`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_fatal(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, !> {
         DiagnosticBuilder::new_fatal(self, msg)
     }
 
     /// Construct a builder at the `Help` level with the `msg`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_help(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, ()> {
         DiagnosticBuilder::new(self, Level::Help, msg)
     }
 
     /// Construct a builder at the `Note` level with the `msg`.
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn struct_note_without_error(
         &self,
         msg: impl Into<DiagnosticMessage>,
     ) -> DiagnosticBuilder<'_, ()> {
         DiagnosticBuilder::new(self, Level::Note, msg)
     }
 
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_fatal(&self, span: impl Into<MultiSpan>, msg: impl Into<DiagnosticMessage>) -> ! {
         self.emit_diag_at_span(Diagnostic::new(Fatal, msg), span);
         FatalError.raise()
     }
 
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_fatal_with_code(
         &self,
         span: impl Into<MultiSpan>,
@@ -817,6 +836,7 @@ impl Handler {
         FatalError.raise()
     }
 
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_err(
         &self,
         span: impl Into<MultiSpan>,
@@ -825,6 +845,7 @@ impl Handler {
         self.emit_diag_at_span(Diagnostic::new(Error { lint: false }, msg), span).unwrap()
     }
 
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_err_with_code(
         &self,
         span: impl Into<MultiSpan>,
@@ -837,10 +858,12 @@ impl Handler {
         );
     }
 
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_warn(&self, span: impl Into<MultiSpan>, msg: impl Into<DiagnosticMessage>) {
         self.emit_diag_at_span(Diagnostic::new(Warning, msg), span);
     }
 
+    #[cfg_attr(not(bootstrap), rustc_lint_diagnostics)]
     pub fn span_warn_with_code(
         &self,
         span: impl Into<MultiSpan>,

compiler/rustc_feature/src/builtin_attrs.rs

@@ -615,6 +615,9 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     // Used by the `rustc::potential_query_instability` lint to warn methods which
     // might not be stable during incremental compilation.
     rustc_attr!(rustc_lint_query_instability, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
+    // Used by the `rustc::untranslatable_diagnostic` and `rustc::diagnostic_outside_of_impl` lints
+    // to assist in changes to diagnostic APIs.
+    rustc_attr!(rustc_lint_diagnostics, Normal, template!(Word), WarnFollowing, INTERNAL_UNSTABLE),
 
     // ==========================================================================
     // Internal attributes, Const related: