fix PR3459: improve compatibility with gcc when checking for constant exprs

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@63517 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaDecl.cpp

@@ -3128,10 +3128,9 @@ static QualType TryToFixInvalidVariablyModifiedType(QualType T,
     
   assert(EvalResult.Val.isInt() && "Size expressions must be integers!");
   llvm::APSInt &Res = EvalResult.Val.getInt();
-  if (Res > llvm::APSInt(Res.getBitWidth(), Res.isUnsigned()))
-    return Context.getConstantArrayType(VLATy->getElementType(),
-                                        Res, ArrayType::Normal, 0);
-  return QualType();
+
+  return Context.getConstantArrayType(VLATy->getElementType(),
+                                      Res, ArrayType::Normal, 0);
 }
 
 bool Sema::VerifyBitField(SourceLocation FieldLoc, IdentifierInfo *FieldName, 

test/Sema/struct-decl.c

@@ -0,0 +1,10 @@
+// RUN: clang -fsyntax-only -verify %s
+
+// PR3459
+struct bar {
+	char n[1];
+};
+
+struct foo {
+	char name[(int)&((struct bar *)0)->n];
+};