P0595R2 is_constant_evaluated()

[StephanTLavavej]

P0595R2 is_constant_evaluated()

This is a compiler feature in a library wrapper. Clang 9 supports the compiler builtin; MSVC's compiler front-end C1XX has implemented it for VS 2019 16.5 Preview 2.

Thanks to @NathanSWard for bringing this paper to my attention (we had Microsoft-internal spreadsheets for the compiler and library, and I converted the library spreadsheet to GitHub issues, but I forgot that I had put this one in the compiler spreadsheet).

Feature-test macro as of WG21-N4842:
#define __cpp_lib_is_constant_evaluated 201811L

[jonwil]

Do you mean VS 2019 16.4 Preview 2? (Given that 16.4 isn't even available yet, let alone a 16.5 Preview 1, I can't see how a 16.5 Preview 2 can exist)

[StephanTLavavej]

I really do mean 16.5 Preview 2 - VS releases are deeply pipelined, with a number of merges and “toolset insertions” required before bits end up shipping publicly.

[SuperWig]

Do you mean VS 2019 16.4 Preview 2?

16.4 is already on Preview 4.
If I'm not mistaken Preview 1 comes out at the same time as a final version,