[WIN] Fix error C7555: use of designated initializers requires at least '/std:c++20'

[whitneywhtsang]

Fixes #4890

[etiotto]

Can we simply change the std level to C++20 instead of changing the code ?

[whitneywhtsang]

Can we simply change the std level to C++20 instead of changing the code ?

It is intentionally made Windows build C++17 compliant: #2837.
The issue doesn't explain why.

[kwasd]

trying to switch to 20 here, not sure about effects: #4891

[kwasd]

Builds with C++20.
So have to merge either #4889 (change code) or #4891 (switch compiler to C++20) to unblock the CI.

[whitneywhtsang]

Builds with C++20. So have to merge either #4889 (change code) or #4891 (switch compiler to C++20) to unblock the CI.

@kwasd Do you know why the error is not reported on Linux? Note upstream set to C++17: https://github.com/triton-lang/triton/blob/main/CMakeLists.txt#L11.

[kwasd]

I have only an assumption: other compiler is not very strict about the standard. Something similar described here.

[kwasd]

It seems like on Linux it use -std=gnu++17 by default.
Setting to -std=c++17 gives other errors, but not this particular case (run)

[kwasd]

The issue doesn't explain why.

By Anatoly
#2833 (comment):

Do you know if upstream is opened to changing to C++20 compliant?

I don't know, it seems to me that there is a connection with PyTorch, which still uses c++17 standard. I suppose that as soon as it updates the standard, Triton will do the same.

[etiotto]

Triton doesn't have to use the same C++ std level that PyTorch uses. Using -std=C++20 would be fine, but I am also fine to fix the source code as per this PR.

[kwasd]

Triton doesn't have to use the same C++ std level that PyTorch uses. Using -std=C++20 would be fine, but I am also fine to fix the source code as per this PR.

There's other C++20-related upstream PRs and discussions
triton-lang/triton#5186
triton-lang/triton#6615
triton-lang/triton#5291