[eastl] Fix error C2338

[Cheney-W]

• What does your PR fix?

  In an internal version of Visual Studio, eastl install failed with following error:
  internal\atomic\atomic_integral.h(330): error C2338: eastl::atomic<T> atomic macro not implemented!

  This issue could be fixed by adding the compile option: /Zc:static_assert- or modifying the source, I added this patch only as a temporary workaround, the specific fix still needs to be discussed with upstream.

No feature need to be tested.

[BillyONeal]

What is the behavior of adding /Zc:static_assert- with older compilers?

[BillyONeal]

I observe that /Zc:static_assert- is not documented: https://docs.microsoft.com/en-us/cpp/build/reference/zc-conformance?view=msvc-170

[Cheney-W]

1. I have compared one by one the output of this port between the older compiler and the latest compiler with /Zc:static_assert- option, I didn't notice any difference.
2. This option is added by Jonathan Caves, please check the related commit for more info.

[BillyONeal]

I asked Jonathan Caves to comment.

[BillyONeal]

(I'm not sure whether 'author response' or 'upstream changes' convey the right tone here but...)

[Cheney-W]

Avoid affecting the PR age, converted this PR to draft.

[BillyONeal]

I know we talked a lot about this change out-of-band; to summarize what I think needs to happen:

• Given that there is no documented behavior for what the compiler does on unrecognized /Zc flags and the existence of clang-cl and friends, I think this needs to be guarded for versions of the compiler new enough to support it.
• Documentation for the new /Zc switch needs to be added to MSDN/docs.microsoft.com/etc.

[JackBoosY]

Ping @Cheney-W

[Cheney-W]

The /Zc:static_assert- option is now recognized in the latest VS2022 17.1.0 Preview 5, but this version should not be able to be used as a judgment node for implementing version protection.
We may have to wait for VS2022 17.1 to be released.

@BillyONeal What do you think about this?

[BillyONeal]

@Cheney-W As long as the version check can be done in CMake world I think it's fine without waiting for 17.1. Perhaps CMAKE_C_COMPILER_VERSION/CMAKE_CXX_COMPILER_VERSION could work?

[github-actions]

You have modified or added at least one vcpkg.json where a "license" field is missing.
If you feel able to do so, please consider adding a "license" field to the following files:

• ports/eastl/vcpkg.json

Valid values for the license field are listed at https://spdx.org/licenses/

[ras0219-msft]

Thanks!