lint: port missing documentation diagnostics

Signed-off-by: David Wood <[email protected]>

Author: davidtwco

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

@@ -324,3 +324,5 @@ lint-builtin-export-name-method = declaration of a method with `export_name`
 lint-builtin-decl-unsafe-fn = declaration of an `unsafe` function
 lint-builtin-decl-unsafe-method = declaration of an `unsafe` method
 lint-builtin-impl-unsafe-method = implementation of an `unsafe` method
+
+lint-builtin-missing-doc = missing documentation for {$article} {$desc}

compiler/rustc_lint/src/builtin.rs

@@ -582,7 +582,10 @@ impl MissingDoc {
                 MISSING_DOCS,
                 cx.tcx.sess.source_map().guess_head_span(sp),
                 |lint| {
-                    lint.build(&format!("missing documentation for {} {}", article, desc)).emit();
+                    lint.build(fluent::lint::builtin_missing_doc)
+                        .set_arg("article", article)
+                        .set_arg("desc", desc)
+                        .emit();
                 },
             );
         }