<intrin.h>: clang-tidy and "expected function body after function declarator"

[ZaldronGG]

Describe the bug
After updating to 16.8.0 Preview 3, I've been getting strange errors from Clang-Tidy. Fearing it was some weird interaction between my MSBuild config, .clang-tidy, the Unity build, or project structure, I tried a simple x64 console project right from the templates and managed to get the same error:

Build started...
1>------ Build started: Project: ClangTidyIssue, Configuration: Debug x64 ------
1>ClangTidyIssue.cpp
Error while processing C:\Darkmere\experiments\ClangTidyIssue\ClangTidyIssue.cpp.
C:\Program Files (x86)\Microsoft Visual Studio\2019\Preview\VC\Tools\MSVC\14.28.29304\include\intrin.h(56,1): error G7973E533: expected function body after function declarator [clang-diagnostic-error]
__MACHINE(void * _AddressOfReturnAddress(void))
^
Suppressed 1 warnings (1 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
Found compiler error(s).
1>Done building project "ClangTidyIssue.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Command-line test case
Just create a new Console Application, Enable Code Analysis on build and Clang-Tidy, build in x64/Debug.

Expected behavior
No compile failures ([clang-diagnostic-error]) every time intrin.h is included.

STL version
Microsoft Visual Studio Community 2019 Preview Version 16.8.0 Preview 3.0

[StephanTLavavej]

Thanks for reporting this issue - while intrin.h is technically not part of the STL repo, we caused this issue by changing the header (ironically, to address other issues with Clang), so instead of asking you to file this on Developer Community, we can continue tracking the issue here. We're a bit busy with CppCon at the moment but we'll try to investigate soon as this is a very recent regression.

[ZaldronGG]

Thanks for the prompt response! I was hesitant to report the issue here as I couldn't find intrin.h, but I was also incapable of logging into Developer Community all day long 😣. Not a blocker of any kind; enjoy the rest of CppCon!

[Agrael1]

Adding to this problem:

1. intrinsics of mm sector including _mm_shuffle_ps turns red and speaks of invalid type conversion
2. for cycle broke away, every declaration inside is red, and usage of iterator inside results in errors

but seems to compile without errors though.

[CaseyCarter]

Given that we have independent reports from users about two different problems caused by this change within two days of the preview release, I think we should make this a priority and try to get it fixed for 16.8.

[StephanTLavavej]

I believe I can fix this (with a change entirely within intrin0.h); unfortunately I believe I've missed the 16.8 cutoff (the bar for porting fixes is very high now, and this doesn't affect the codegen compilers).

[StephanTLavavej]

I believe I've fixed this with Microsoft-internal MSVC-PR-278849 which will ship in VS 2019 16.9 Preview 2.

[PathogenDavid]

@StephanTLavavej

Thanks for getting this issue fixed! Since the change won't be making it into 16.8, can you share with us any details of what the fix was? It might make it easier for us to work around the issue ourselves.

[CaseyCarter]

@ParthogenDavid Here's the actual diff for the fix we applied.

GH-1300.diff.txt

[PathogenDavid]

Thanks, that's perfect!

[eiband]

I'm a bit confused. Does this mean that 16.8 is incompatible with clang and we will have no fix for the next months? Using VC 2019 16.9 Preview is not an option for me.