When building on Windows w/swiftc, can accidently include both msvc and gcc math.inls.

[jeffdav]

Describe the bug

On Windows, I'm building aws-sdk-swift using CMake. I build aws-c-* using ExternalProject_Add().
(Thank you for providing CMakeLists.txt for your projects!)

The issue is when building aws-sdk-swift, we end up using clang, which causes math.h include both math.msvc.inl and math.gcc_builtin.inl during module import, leading to duplicate symbols.

Expected Behavior

We should only include one or the other.

Current Behavior

We include both.

Reproduction Steps

Build aws-sdk-swift using CMake on Windows. I'm happy to share my CMakeLists.txt for doing this if it is helpful.

Possible Solution

Currently I'm patching:

#if defined(__clang__) || defined(__GNUC__)

To:

#if (defined(__clang__) || defined(__GNUC__)) && !defined(AWS_HAVE_MSVC_INTRINSICS_X64)
#    include <aws/common/math.gcc_builtin.inl>
#endif

I'm not 100% certain this is the most correct, but it works.

Additional Information/Context

No response

aws-c-common version used

commit 6978946 (origin/main, origin/HEAD, main)

Compiler and version used

swiftc: compnerd.org Swift version 6.0-dev (LLVM a527f49f462b0d7, Swift eef85a7be270421), clang: compnerd.org clang version 17.0.6, cl: Microsoft (R) C/C++ Optimizing Compiler Version 19.41.34120 for x64

Operating System and version

Windows 11 23H2

[TingDaoK]

Yeah, please share the CMakeLists, which will help us to reproduce the issue.

[jmklix]

Please note that it is still a feature request to get swiftc working on windows. As mentioned here by @waahm7

Currently, both Aws-crt-swift and Aws-sdk-swift don't support Windows. This is a feature request, and I think we will probably hit more issues than just awslabs/aws-crt-swift#290 to properly support Windows and also add CI for it. Swift SDK might have to do some work as well on their side. We have added this to our backlog and will update here as soon as we have any updates.

Please 👍 the original issue and that will help us prioritize this.

[jjerphan]

I also have this issue when building using clang-cl a project depending transitively on aws-c-common (see man-group/ArcticDB@9323534 from man-group/ArcticDB#2252).

Might AWS_HAVE_MSVC_INTRINSICS_X64 and __clang__ be defined by clang-cl?

[jjerphan]

#1194 was opened to propose a solution.