middle: translation in LintDiagnosticBuilder

Accept `DiagnosticMessage` in `LintDiagnosticBuilder::build` so that
lints can be built with translatable diagnostic messages.

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

compiler/rustc_errors/src/diagnostic_builder.rs

@@ -529,7 +529,7 @@ pub fn span_labels(
         applicability: Applicability,
     ) -> &mut Self);
 
-    forward!(pub fn set_primary_message(&mut self, msg: impl Into<String>) -> &mut Self);
+    forward!(pub fn set_primary_message(&mut self, msg: impl Into<DiagnosticMessage>) -> &mut Self);
     forward!(pub fn set_span(&mut self, sp: impl Into<MultiSpan>) -> &mut Self);
     forward!(pub fn code(&mut self, s: DiagnosticId) -> &mut Self);
     forward!(pub fn set_arg(

compiler/rustc_lint/src/levels.rs

@@ -521,7 +521,7 @@ pub(crate) fn push(
                             src,
                             Some(sp.into()),
                             |lint| {
-                                let mut err = lint.build(&msg);
+                                let mut err = lint.build(msg);
                                 if let Some(new_name) = &renamed {
                                     err.span_suggestion(
                                         sp,
@@ -548,7 +548,7 @@ pub(crate) fn push(
                             } else {
                                 name.to_string()
                             };
-                            let mut db = lint.build(&format!("unknown lint: `{}`", name));
+                            let mut db = lint.build(format!("unknown lint: `{}`", name));
                             if let Some(suggestion) = suggestion {
                                 db.span_suggestion(
                                     sp,

compiler/rustc_middle/src/lint.rs

@@ -3,7 +3,8 @@
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_errors::{
-    Diagnostic, DiagnosticBuilder, DiagnosticId, EmissionGuarantee, ErrorGuaranteed, MultiSpan,
+    Diagnostic, DiagnosticBuilder, DiagnosticId, DiagnosticMessage, EmissionGuarantee,
+    ErrorGuaranteed, MultiSpan,
 };
 use rustc_hir::HirId;
 use rustc_index::vec::IndexVec;
@@ -231,7 +232,7 @@ pub fn new(
 
 impl<'a, G: EmissionGuarantee> LintDiagnosticBuilder<'a, G> {
     /// Return the inner `DiagnosticBuilder`, first setting the primary message to `msg`.
-    pub fn build(mut self, msg: &str) -> DiagnosticBuilder<'a, G> {
+    pub fn build(mut self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'a, G> {
         self.0.set_primary_message(msg);
         self.0.set_is_lint();
         self.0

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -550,7 +550,7 @@ fn recur(
                         id,
                         span,
                         |lint| {
-                            lint.build(&msg).emit();
+                            lint.build(msg).emit();
                         },
                     );
                 }

compiler/rustc_passes/src/check_attr.rs

@@ -1163,7 +1163,7 @@ fn check_doc_attrs(
                         hir_id,
                         meta.span(),
                         |lint| {
-                            lint.build(&"invalid `doc` attribute").emit();
+                            lint.build("invalid `doc` attribute").emit();
                         },
                     );
                     is_valid = false;