Protect std::ios tests under libcpp-no-exceptions

Skip tests that expect an exception be thrown. Also add
some missing asserts in the original test.

Differential Revision: https://reviews.llvm.org/D26512



git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@286823 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/input.output/iostreams.base/ios/iostate.flags/clear.pass.cpp

@@ -7,7 +7,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-// XFAIL: libcpp-no-exceptions
 // <ios>
 
 // template <class charT, class traits> class basic_ios
@@ -18,6 +17,8 @@
 #include <streambuf>
 #include <cassert>
 
+#include "test_macros.h"
+
 struct testbuf : public std::streambuf {};
 
 int main()
@@ -26,9 +27,11 @@ int main()
         std::ios ios(0);
         ios.clear();
         assert(ios.rdstate() == std::ios::badbit);
+#ifndef TEST_HAS_NO_EXCEPTIONS
         try
         {
             ios.exceptions(std::ios::badbit);
+            assert(false);
         }
         catch (...)
         {
@@ -51,6 +54,7 @@ int main()
         {
             assert(ios.rdstate() == (std::ios::eofbit | std::ios::badbit));
         }
+#endif
     }
     {
         testbuf sb;