x86 clang compilation broken

[hummeleBop]

Hey there,

I'm still using clang-check to get more warnings from my source code.
However, since the last update, I get the following errors :

out-herschel-uwp\Generated Files\winrt/base.h(4098,18): error: assigning to 'int (*)(unsigned int, const winrt::guid &,       void *, void **) __attribute__((stdcall)) noexcept' from incompatible type '(lambda at out-herschel-uwp\Generated       Files\winrt/base.h:4106:13)'
        result = fallback;
                 ^~~~~~~~
out-herschel-uwp\Generated Files\winrt/base.h(4105,9): note: in instantiation of function template specialization             'winrt::impl::load_runtime_function<int (*)(unsigned int, const winrt::guid &, void *, void **)
      __attribute__((stdcall)) noexcept, (lambda at out-herschel-uwp\Generated Files\winrt/base.h:4106:13)>' requested
      here
        load_runtime_function("RoGetAgileReference", handler,
        ^
out-herschel-uwp\Generated Files\winrt/base.h(4098,18): error: assigning to 'int (*)(int, void *, void *)
      __attribute__((stdcall)) noexcept' from incompatible type '(lambda at out-herschel-uwp\Generated
      Files\winrt/base.h:4474:17)'
        result = fallback;
                 ^~~~~~~~
out-herschel-uwp\Generated Files\winrt/base.h(4473,19): note: in instantiation of function template specialization            'winrt::impl::load_runtime_function<int (*)(int, void *, void *) __attribute__((stdcall)) noexcept, (lambda at
      out-herschel-uwp\Generated Files\winrt/base.h:4474:17)>' requested here
            impl::load_runtime_function("RoOriginateLanguageException", handler,
                  ^
out-herschel-uwp\Generated Files\winrt/base.h(4098,18): error: assigning to 'void (*)(int) __attribute__((stdcall))           noexcept' from incompatible type '(lambda at out-herschel-uwp\Generated Files\winrt/base.h:4745:13)'
        result = fallback;
                 ^~~~~~~~
out-herschel-uwp\Generated Files\winrt/base.h(4744,15): note: in instantiation of function template specialization            'winrt::impl::load_runtime_function<void (*)(int) __attribute__((stdcall)) noexcept, (lambda at
      out-herschel-uwp\Generated Files\winrt/base.h:4745:13)>' requested here
        impl::load_runtime_function("RoFailFastWithErrorContext", handler,
              ^
out-herschel-uwp\Generated Files\winrt/base.h(4098,18): error: assigning to 'int (*)(void *, const winrt::guid &, void
      **) __attribute__((stdcall)) noexcept' from incompatible type '(lambda at out-herschel-uwp\Generated
      Files\winrt/base.h:5626:13)'
        result = fallback;
                 ^~~~~~~~
out-herschel-uwp\Generated Files\winrt/base.h(5625,15): note: in instantiation of function template specialization
      'winrt::impl::load_runtime_function<int (*)(void *, const winrt::guid &, void **) __attribute__((stdcall))              noexcept, (lambda at out-herschel-uwp\Generated Files\winrt/base.h:5626:13)>' requested here
        impl::load_runtime_function("RoGetActivationFactory", handler,
              ^

It doesn't seem to be a big issue, but it could be great to have a fix :)

Have a nice day

[kennykerr]

Is there a way to have clang-cl produce these warnings/errors? Here's how I'm testing Clang today - if there is a way to tweak this to be stricter that would be great. I have tested with LLVM 9 and my test compiles without warning.

[hummeleBop]

The issue is when the flag -m32 is landed.

clang-cl minimal.cpp /std:c++17 /EHsc -Xclang -fcoroutines-ts -Xclang -isystem".\generated" -m32

[hummeleBop]

I know clang won't be able to deal with XAML anytime soon (I'm aware cppwinrt needs to use some C++/CX code fragments).
but the headers inclusion shouldn't break:

In file included from \Generated Files\winrt/Windows.UI.Xaml.h:28:
In file included from \Generated Files\winrt/impl/Windows.UI.Xaml.Media.Animation.2.h:9:
In file included from \Generated Files\winrt/impl/Windows.UI.Xaml.Media.Animation.1.h:5:
\Generated Files\winrt/impl/Windows.UI.Xaml.Media.Animation.0.h(2305,54): error: too many arguments provided to function-like macro invocation
            virtual int32_t __stdcall GetCurrentTime(int64_t*) noexcept = 0;
                                                     ^
C:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um\winbase.h(95,9): note: macro 'GetCurrentTime' defined here
#define GetCurrentTime()                GetTickCount()
        ^
In file included from \Generated Files\winrt/Windows.UI.Xaml.h:28:
In file included from \Generated Files\winrt/impl/Windows.UI.Xaml.Media.Animation.2.h:9:
In file included from \Generated Files\winrt/impl/Windows.UI.Xaml.Media.Animation.1.h:5:
\Generated Files\winrt/impl/Windows.UI.Xaml.Media.Animation.0.h(2305,13): error: 'virtual' can only appear on non-static member functions
            virtual int32_t __stdcall GetCurrentTime(int64_t*) noexcept = 0;
            ^
\Generated Files\winrt/impl/Windows.UI.Xaml.Media.Animation.0.h(2305,53): error: expected ';' at end of declaration list
            virtual int32_t __stdcall GetCurrentTime(int64_t*) noexcept = 0;
                                                    ^

I'm sorry to be such a bother in this area..
You're probably busy a lot with more relevant things to do.

[kennykerr]

Xaml doesn't require C++/CX.

The issue here is that GetCurrentTime is a macro that you've introduced before including C++/WinRT headers. I have no control over this, but you can fix it yourself as follows:

#include <Windows.h>
#undef GetCurrentTime
#include "winrt/Windows.UI.Xaml.Media.Animation.h"

[hummeleBop]

I wonder why I thought the XAML generation process was related to C++/CX
Thanks for all 👍

[kennykerr]

I see the problem with the -m32 errors. In that mode, Clang is honoring the __stdcall calling convention, but the calling convention of the lambda conflicts with that of the function pointer. Visual C++ implements all calling conventions for lambdas while inexplicably Clang does not so I end up having to change the lambdas into functions.