[Clang][Sema] set declaration invalid earlier to prevent crash in calculating record layout

Author: huqizhi

clang/docs/ReleaseNotes.rst

@@ -465,6 +465,8 @@ Bug Fixes to C++ Support
   following the first `::` were ignored).
 - Fix an out-of-bounds crash when checking the validity of template partial specializations. (part of #GH86757).
 - Fix an issue caused by not handling invalid cases when substituting into the parameter mapping of a constraint. Fixes (#GH86757).
+- Fix a crash caused by defined struct in a type alias template when the structure
+  has fields with dependent type. Fixes (#GH75221).
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaType.cpp

@@ -3899,6 +3899,9 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
       SemaRef.Diag(OwnedTagDecl->getLocation(), DiagID)
           << SemaRef.Context.getTypeDeclType(OwnedTagDecl);
       D.setInvalidType(true);
+      OwnedTagDecl->setCompleteDefinition(false);
+      OwnedTagDecl->setInvalidDecl();
+      OwnedTagDecl->setCompleteDefinition();
     }
   }
 

clang/test/SemaCXX/PR75221.cpp

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -verify -std=c++11 -fsyntax-only %s
+// expected-no-diagnostics
+
+template <class T> using foo = struct foo {
+  T size = 0;
+};
+foo a;