empty_label

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1,5 +1,5 @@
-// #![deny(rustc::untranslatable_diagnostic)]
-// #![deny(rustc::diagnostic_outside_of_impl)]
+#![deny(rustc::untranslatable_diagnostic)]
+#![deny(rustc::diagnostic_outside_of_impl)]
 
 use rustc_errors::{
     Applicability, Diagnostic, DiagnosticBuilder, EmissionGuarantee, ErrorGuaranteed,
@@ -1047,8 +1047,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     kind: hir::ImplItemKind::Fn(sig, _),
                     ..
                 }) => {
-                    //FIXME: empty string here don't pass lint
-                    err.span_label(ident.span, "");
+                    err.subdiagnostic(FnMutBumpFn::EmptyLabel { span: ident.span });
                     err.subdiagnostic(FnMutBumpFn::ReturnFnMut { span: sig.decl.output.span() });
                     err.subdiagnostic(FnMutBumpFn::Here { span: self.body.span });
                 }

compiler/rustc_borrowck/src/session_diagnostics.rs

@@ -157,7 +157,7 @@ pub(crate) enum RequireStaticErr {
         multi_span: MultiSpan,
     },
 }
-//mutability_errors.rs
+
 #[derive(SessionSubdiagnostic)]
 pub(crate) enum ShowMutatingUpvar {
     #[label(borrowck::require_mutable_binding)]
@@ -187,6 +187,11 @@ pub(crate) enum FnMutBumpFn<'a> {
         #[primary_span]
         span: Span,
     },
+    #[label(borrowck::empty_label)]
+    EmptyLabel {
+        #[primary_span]
+        span: Span,
+    },
     #[label(borrowck::in_this_closure)]
     Here {
         #[primary_span]

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

@@ -71,6 +71,8 @@ borrowck_expects_fnmut_not_fn =
 borrowck_expects_fn_not_fnmut =
     expects `Fn` instead of `FnMut`
 
+borrowck_empty_label = {""}
+
 borrowck_in_this_closure =
     in this closure