Fix isIntegerConstantExpr eval of __builtin_offsetof to return result
with correct width.
 - PR2728.

Also, fix PR2727 test case.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@55493 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Sema/PR2728.c b/test/Sema/PR2728.c
new file mode 100644
index 0000000..01a3be7
--- /dev/null
+++ b/test/Sema/PR2728.c
@@ -0,0 +1,9 @@
+// RUN: clang -verify -fsyntax-only -std=c90 %s &&
+// RUN: clang -verify -fsyntax-only -std=c99 %s
+
+struct s
+{
+  int a;
+};
+
+int a[__builtin_offsetof(struct s, a) == 0];