lint: port keyword idents diagnostics

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

compiler/rustc_error_messages/locales/en-US/lint.ftl

@@ -373,3 +373,6 @@ lint-builtin-ellipsis-inclusive-range-patterns = `...` range patterns are deprec
     .suggestion = use `..=` for an inclusive range
 
 lint-builtin-unnameable-test-items = cannot test inner items
+
+lint-builtin-keyword-idents = `{$kw}` is a keyword in the {$next} edition
+    .suggestion = you can use a raw identifier to stay compatible

compiler/rustc_errors/src/diagnostic.rs

@@ -8,7 +8,7 @@
 use rustc_lint_defs::{Applicability, LintExpectationId};
 use rustc_span::edition::LATEST_STABLE_EDITION;
 use rustc_span::symbol::{Ident, Symbol};
-use rustc_span::{Span, DUMMY_SP};
+use rustc_span::{edition::Edition, Span, DUMMY_SP};
 use std::borrow::Cow;
 use std::fmt;
 use std::hash::{Hash, Hasher};
@@ -115,6 +115,12 @@ fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
     }
 }
 
+impl IntoDiagnosticArg for Edition {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::Str(Cow::Owned(self.to_string()))
+    }
+}
+
 impl IntoDiagnosticArg for Symbol {
     fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
         self.to_ident_string().into_diagnostic_arg()

compiler/rustc_lint/src/builtin.rs

@@ -2033,10 +2033,12 @@ fn check_ident_token(
         }
 
         cx.struct_span_lint(KEYWORD_IDENTS, ident.span, |lint| {
-            lint.build(&format!("`{}` is a keyword in the {} edition", ident, next_edition))
+            lint.build(fluent::lint::builtin_keyword_idents)
+                .set_arg("kw", ident.clone())
+                .set_arg("next", next_edition)
                 .span_suggestion(
                     ident.span,
-                    "you can use a raw identifier to stay compatible",
+                    fluent::lint::suggestion,
                     format!("r#{}", ident),
                     Applicability::MachineApplicable,
                 )