[libc++] Undef min/max in test_macros.h

[EricWF]

Summary

After changing libc++ to push/pop the min/max macros on Windows we have a bunch of new test failures, caused by tests using min/max. I would like to use test_macros.h to undefine it.

Would this work for you? How have you been dealing with these failures?

[STL_MSFT]

I haven't seen min/max test failures, probably because our CRT/STL headers never drag in Windows.h.

I have no objection to undeffing min/max although I wouldn't do this myself (it creates order dependencies which I think are totally evil).

[EricWF]

In D33741#769371, @STL_MSFT wrote:

I haven't seen min/max test failures, probably because our CRT/STL headers never drag in Windows.h.

Ah, that makes sense. Libc++ currently does although the plan is to fix that eventually. :-S

I have no objection to undeffing min/max although I wouldn't do this myself (it creates order dependencies which I think are totally evil).

Yeah, the header order is super evil. Agreed.

[CaseyCarter]

In D33741#769381, @EricWF wrote:

In D33741#769371, @STL_MSFT wrote:

I haven't seen min/max test failures, probably because our CRT/STL headers never drag in Windows.h.

Ah, that makes sense. Libc++ currently does although the plan is to fix that eventually. :-S

Are you aware that Windows.h won't define min and max if you define NOMINMAX before including it? You could solve the problem by adding -DNOMINMAX to your test compile parameters.

[EricWF]

In D33741#769421, @CaseyCarter wrote:

In D33741#769381, @EricWF wrote:

In D33741#769371, @STL_MSFT wrote:

I haven't seen min/max test failures, probably because our CRT/STL headers never drag in Windows.h.

Ah, that makes sense. Libc++ currently does although the plan is to fix that eventually. :-S

Are you aware that Windows.h won't define min and max if you define NOMINMAX before including it? You could solve the problem by adding -DNOMINMAX to your test compile parameters.

I want to avoid modifying how Windows.h is included in the libc++ headers, in case people actually depend on that macro.

However passing -DNOMINMAX as a test compiler parameter is a much better solution. Thanks!

test/support/test_macros.h

 template <class Tp>
 inline void DoNotOptimize(Tp const& value) {
   const volatile void* volatile unused = __builtin_addressof(value);
   static_cast<void>(unused);
   _ReadWriteBarrier();
 }
 #endif
 
+#if defined(min)
+#undef min
+#endif
+
+#if defined(max)
+#undef max
+#endif
+
 #if defined(__GNUC__)
 #pragma GCC diagnostic pop
 #endif
 
 #endif // SUPPORT_TEST_MACROS_HPP