Auto merge of #118687 - matthiaskrgr:rollup-317ztgu, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #117981 (Remove deprecated `--check-cfg` syntax)
 - #118177 (Suppress warnings in LLVM wrapper when targeting MSVC)
 - #118317 (tip for define macro name after `macro_rules!`)
 - #118504 (Enforce `must_use` on associated types and RPITITs that have a must-use trait in bounds)
 - #118660 (rustc_arena: add `alloc_str`)
 - #118681 (Fix is_foreign_item for StableMIR instance )

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_resolve/src/diagnostics.rs

@@ -27,10 +27,8 @@ use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, Span, SyntaxContext};
 use thin_vec::{thin_vec, ThinVec};
 
-use crate::errors::{
-    AddedMacroUse, ChangeImportBinding, ChangeImportBindingSuggestion, ConsiderAddingADerive,
-    ExplicitUnsafeTraits,
-};
+use crate::errors::{AddedMacroUse, ChangeImportBinding, ChangeImportBindingSuggestion};
+use crate::errors::{ConsiderAddingADerive, ExplicitUnsafeTraits, MaybeMissingMacroRulesName};
 use crate::imports::{Import, ImportKind};
 use crate::late::{PatternSource, Rib};
 use crate::path_names_to_string;
@@ -1421,14 +1419,21 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             "",
         );
 
+        if macro_kind == MacroKind::Bang && ident.name == sym::macro_rules {
+            err.subdiagnostic(MaybeMissingMacroRulesName { span: ident.span });
+            return;
+        }
+
         if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
             err.subdiagnostic(ExplicitUnsafeTraits { span: ident.span, ident });
             return;
         }
+
         if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
             err.subdiagnostic(AddedMacroUse);
             return;
         }
+
         if ident.name == kw::Default
             && let ModuleKind::Def(DefKind::Enum, def_id, _) = parent_scope.module.kind
         {

compiler/rustc_resolve/src/errors.rs

@@ -665,6 +665,13 @@ pub(crate) struct ExplicitUnsafeTraits {
     pub(crate) ident: Ident,
 }
 
+#[derive(Subdiagnostic)]
+#[note(resolve_missing_macro_rules_name)]
+pub(crate) struct MaybeMissingMacroRulesName {
+    #[primary_span]
+    pub(crate) span: Span,
+}
+
 #[derive(Subdiagnostic)]
 #[help(resolve_added_macro_use)]
 pub(crate) struct AddedMacroUse;