<yvals_core.h>: Remove _HAS_STD_BYTE someday

[StephanTLavavej]

After microsoft/GSL#821 "gsl_byte should inspect __cpp_lib_byte in addition to _HAS_STD_BYTE" is fixed, _HAS_STD_BYTE should no longer be needed for detection.

After the Windows SDK's unqualified mentions of byte (referring to their own ::byte) are fixed, _HAS_STD_BYTE should no longer be needed for control.

Then we can finally remove:

STL/stl/inc/yvals_core.h

Lines 475 to 477 in 447f879

	#ifndef _HAS_STD_BYTE
	#define _HAS_STD_BYTE _HAS_CXX17 // inspected by GSL, do not remove
	#endif // _HAS_STD_BYTE

Also, I created microsoft/GSL#1145 so that GSL will no longer inspect _HAS_STD_BYTE at all.

[JordanMaples]

gsl_byte now inspects __cpp_lib_byte, this should unblock you.

[StephanTLavavej]

Great, thank you! We’re still blocked on the WinSDK needing this as an escape hatch, but your quick fix to GSL means that there will be plenty of time for users to update their dependencies.

[StephanTLavavej]

Microsoft-internal WinSDK issue: OS-11785508 "Make Windows headers compatible with C++17 std::byte".

[miscco]

Out of curriosity can this be closed now that the __cpp_lib_byte change is implemented

[CaseyCarter]

Out of curiosity can this be closed now that the __cpp_lib_byte change is implemented

OS-11785508 hasn't been addressed yet.

[Zingam]

@StephanTLavavej Was support for std::byte removed in VS2019 16.8? It looks like __cpp_lib_byte isn't defined.

[CaseyCarter]

@StephanTLavavej Was support for std::byte removed in VS2019 16.8? It looks like __cpp_lib_byte isn't defined.

We define it unless someone explicitly disables std::byte by defining _HAS_STD_BYTE to 0 before yvals_core.h is first included:

STL/stl/inc/yvals_core.h

Lines 1115 to 1117 in 9959929

	#if _HAS_STD_BYTE
	#define __cpp_lib_byte 201603L
	#endif // _HAS_STD_BYTE

[StephanTLavavej]

And you have to be compiling in /std:c++17 or /std:c++latest mode in order to get std::byte (and its feature-test macro).

[karam-jaber-intel]

Is this issue fixed, if not, Is there an ETA for fix?

[StephanTLavavej]

No ETA; the Microsoft-internal WinSDK issue OS-11785508 "Make Windows headers compatible with C++17 std::byte" is still open.

I'm not sure how many unqualified mentions of byte remain in the Windows SDK.