[AST][RecoveryExpr] Fix a crash on a field decl with invalid type.

Summary:
The field decl (in the testcase) was still valid, which results in a
valid RecordDecl, it led to crash when performing struct layout,
and computing struct size etc.

Reviewers: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D81913

clang/lib/Sema/SemaDecl.cpp

@@ -16479,7 +16479,7 @@ FieldDecl *Sema::CheckFieldDecl(DeclarationName Name, QualType T,
 
   // If we receive a broken type, recover by assuming 'int' and
   // marking this declaration as invalid.
-  if (T.isNull()) {
+  if (T.isNull() || T->containsErrors()) {
     InvalidDecl = true;
     T = Context.IntTy;
   }

clang/test/Sema/invalid-member.cpp

@@ -13,3 +13,9 @@ class Y {
 };
 // Should be able to evaluate sizeof without crashing.
 static_assert(sizeof(Y) == 1, "No valid members");
+
+class Z {
+  int array[sizeof(invalid())]; // expected-error {{use of undeclared identifier}}
+};
+// Should be able to evaluate sizeof without crashing.
+static_assert(sizeof(Z) == 1, "No valid members");