Check for an invalid field earlier in a constructor's initialization

of that field. Otherwise, we can end up building and later trying to
instantiate a dependent member initializer that will fail at
instantiation time. 

Unfortunately, I've only managed to trigger this bug with very large
sources, so there's no test case :(

llvm-svn: 118306

clang/lib/Sema/SemaDeclCXX.cpp

@@ -1252,6 +1252,9 @@ Sema::BuildMemberInitializer(FieldDecl *Member, Expr **Args,
                              unsigned NumArgs, SourceLocation IdLoc,
                              SourceLocation LParenLoc,
                              SourceLocation RParenLoc) {
+  if (Member->isInvalidDecl())
+    return true;
+  
   // Diagnose value-uses of fields to initialize themselves, e.g.
   //   foo(foo)
   // where foo is not also a parameter to the constructor.
@@ -1294,9 +1297,6 @@ Sema::BuildMemberInitializer(FieldDecl *Member, Expr **Args,
     
   }
   
-  if (Member->isInvalidDecl())
-    return true;
-  
   // Initialize the member.
   InitializedEntity MemberEntity =
     InitializedEntity::InitializeMember(Member, 0);