[clang] [clang] Improved diagnostics for explicit specialization/instantiation of closure type members (PR #192843)

[Timm Baeder via cfe-commits]

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@@ -16331,10 +16331,13 @@ Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Decl *D,
   // have the LSI properly restored.
   if (isGenericLambdaCallOperatorSpecialization(FD)) {
     // C++2c 7.5.5.2p17 A member of a closure type shall not be explicitly
-    // instantiated, explicitly specialized.
-    if (FD->getTemplateSpecializationInfo()
-            ->isExplicitInstantiationOrSpecialization()) {
-      Diag(FD->getLocation(), diag::err_lambda_explicit_spec);
+    // specialized.
+    if (FD->getTemplateSpecializationInfo()->isExplicitSpecialization()) {
+      Diag(FD->getLocation(), diag::err_lambda_explicit_temp_spec)
+          << /*specialization*/ 0;
+      CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(FD->getParent());
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tbaederr wrote:

This either needs to be `cast<>` or you need to check the result for `nullptr`.

https://github.com/llvm/llvm-project/pull/192843