C++ ClangCL on Windows - `/wd4668` flag results in error

[szymonj99]

C++ ClangCL on Windows - `/wd4668` flag results in error

[glandium]

Related to #1730 ?

[szymonj99]

I think the error is unrelated, but the fix is what's causing the issue (correct me if I'm wrong) (I've compiled sccache from source with commit 6bfe2cbdbd4bfceecadd35a9c5b19586eb7161f2 from 19th June, and the issue persisted; I had no issues with the warning that the original PR references (error C4668: '__midl' is not defined as a preprocessor macro, replacing with '0' for '#if/#elif'). I'm running version 0.5.4 right now which has that fix included.

[sylvestre]

cc @Alexei-Barnes if you have an idea

[cctv130]

After testing, you can add comments to wd4668, in msvc.rs, then recompile sccache, after that you can use clang-cl.

[szymonj99]

I'll do more testing on my side and report back; I seem to have fixed the issue now, and I'm not 100% sure why.

[cctv130]

I'll do more testing on my side and report back; I seem to have fixed the issue now, and I'm not 100% sure why.

clang-cl, as I know, is not fully compatible with msvc, so it seems that clang-cl will not handle the wd4668 error, while msvc will handle the wd4668 error.

[aeubanks]

clang-cl handles /wd4668 just fine, the actual problem is that it's getting passed at the very end of the command line after a --, so it gets treated as a file to compile rather than a flag

the same thing happens with MSVC, it's just that MSVC doesn't recognize -- and I see the following when using sccache with cl (and don't see it without sccache)

cl : Command line warning D9002 : ignoring unknown option '--'

so MSVC treats /wd4668 at the end of the command like a flag

[glandium]

So, this is a dupe of #1498 then

[aeubanks]

in some sense yes, fixing #1498 would also fix this, but the currently proposed fix #1856 is also reasonable but would only fix this