[clang] [clang][Sema] Add diagnostic note for reference of function-like macros requiring without parentheses (PR #123495)

[via cfe-commits]

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@@ -2548,6 +2548,28 @@ Sema::BuildDeclRefExpr(ValueDecl *D, QualType Ty, ExprValueKind VK,
   return E;
 }
 
+// Diagnose when a macro cannot be expanded because it's a function-like macro
+// being used as an object-like macro. Returns true if a diagnostic is emitted.
+static bool diagnoseFunctionLikeMacro(Sema &SemaRef, DeclarationName Name,
+                                      SourceLocation TypoLoc) {
+
+  if (IdentifierInfo *II = Name.getAsIdentifierInfo()) {
+    if (II->hasMacroDefinition()) {
+      MacroInfo *MI = SemaRef.PP.getMacroInfo(II);
+      if (MI && MI->isFunctionLike()) {
+        SemaRef.Diag(TypoLoc,
+                     diag::err_undeclared_var_use_suggest_func_like_macro)
+            << II->getName();
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StarOne01 wrote:

xD, Let me know if there's anything else you'd like changed.

https://github.com/llvm/llvm-project/pull/123495