Bug: Missing `<intrin.h>` in `winrt.Windows.Foundation.ixx` in module builds

Đọc phần global module fragment trong winrt.Windows.Foundation.ixx và so sánh các include của nó với cách _InterlockedCompareExchangePointer được sử dụng trong Windows.Foundation.h. Thêm khai báo intrinsic còn thiếu vào quá trình build module và biên dịch module Windows.Foundation bằng GCC hoặc Clang để xác nhận lỗi tra cứu được báo cáo đã hết.

Version

3.0.260818.1

Summary

In C++20 module builds (-modules), the global module fragment of winrt.Windows.Foundation.ixx does not include <intrin.h>, even though the coroutine helpers in Windows.Foundation.h (winrt::when_any) directly call _InterlockedCompareExchangePointer.

Because <intrin.h> is only included in the global module fragment of winrt_base.ixx and is not exported across modules, _InterlockedCompareExchangePointer has no visible declaration in winrt.Windows.Foundation.ixx:

• GCC and Clang (targeting MinGW) reject winrt.Windows.Foundation.ixx during template definition lookup.
• Clang (targeting MSVC) masks this because -fms-extensions treats the intrinsic as a predeclared compiler builtin.
• MSVC masks this only because an earlier template instantiation in Windows.Foundation.h happens to pull the global module fragment declaration from winrt_base.ifc into scope before winrt::when_any is parsed.

Here is a minimal reproducible example for the msvc compiler bug:

// hidden.h
inline int hidden(int value)
{
    return value;
}

// mod.ixx
module;
#include "hidden.h"

export module provider;

export template <class T>
auto touch(T value)
{
    return hidden(value);
}

// main.cpp
import provider;

int test()
{
    touch(0);          // Instantiating the template leaks `hidden` into scope
    return hidden(42); // MSVC erroneously allows unqualified lookup to find `hidden`
}

Reproducible example

$out = Join-Path $env:TEMP "cppwinrt_intrin_repro"
Remove-Item -Recurse -Force $out -ErrorAction SilentlyContinue
New-Item -ItemType Directory -Force -Path $out | Out-Null
Push-Location $out

# 1. Generate module projection with cppwinrt 3.0.260818.1
$cppwinrt = "$env:USERPROFILE\.nuget\packages\microsoft.windows.cppwinrt\3.0.260818.1\bin\cppwinrt.exe"
& $cppwinrt -in local -out $out -modules -include Windows.Foundation

# Assume upstream fix for `export extern "C"` in winrt/base.h
# $baseH = Get-Content "winrt/base.h" -Raw
# $idx = $baseH.IndexOf('extern "C"')
# Set-Content "winrt/base.h" ($baseH.Substring(0, $idx) + 'export extern "C"' + $baseH.Substring($idx + 10))

# 2. MSVC
$vsDevCmd = "C:\Program Files\Microsoft Visual Studio\18\Community\Common7\Tools\VsDevCmd.bat"
$stdIxx = Get-ChildItem "C:\Program Files\Microsoft Visual Studio\18\Community\VC\Tools\MSVC\*\modules\std.ixx" |
          Select-Object -Last 1 -ExpandProperty FullName
$msvcCmds = @(
    "`"$vsDevCmd`" -arch=x64 -no_logo"
    "cd /d `"$out`""
    "cl /nologo /std:c++20 /EHsc /MD /c /interface /TP `"$stdIxx`" /ifcOutput std.ifc"
    "cl /nologo /std:c++20 /EHsc /MD /I. /c /interface /TP winrt/winrt_numerics.ixx /ifcOutput winrt_numerics.ifc"
    "cl /nologo /std:c++20 /EHsc /MD /I. /c /interface /TP winrt/winrt_base.ixx /reference std=std.ifc /reference winrt_numerics=winrt_numerics.ifc /ifcOutput winrt_base.ifc"
    "cl /nologo /std:c++20 /EHsc /MD /I. /c /interface /TP winrt/winrt.Windows.Foundation.ixx /reference std=std.ifc /reference winrt_numerics=winrt_numerics.ifc /reference winrt_base=winrt_base.ifc /ifcOutput winrt.Windows.Foundation.ifc"
) -join " && "
cmd /c $msvcCmds

# 3. GCC
(Get-Content "winrt/winrt_numerics.ixx" -Raw) -replace '#include <intrin.h>', "#include <x86intrin.h>`n#include <algorithm>`n#include <cmath>`n#include <intrin.h>" | Set-Content "winrt/winrt_numerics.ixx"
(Get-Content "winrt/winrt_base.ixx" -Raw) -replace '#include <intrin.h>', "#include <x86intrin.h>`n#include <intrin.h>" | Set-Content "winrt/winrt_base.ixx"

$stdCc = Get-ChildItem "C:\Tools\msys64\ucrt64\include\c++\*\bits\std.cc" | Select-Object -First 1 -ExpandProperty FullName
g++ -std=c++23 -fmodules -c "$stdCc" -o std.o
g++ -std=c++23 -fmodules -I. -x c++ -c winrt/winrt_numerics.ixx -o winrt_numerics.o
g++ -std=c++23 -fmodules -I. -x c++ -c winrt/winrt_base.ixx -o winrt_base.o
g++ -std=c++23 -fmodules -I. -x c++ -c winrt/winrt.Windows.Foundation.ixx -o winrt.Windows.Foundation.o

Pop-Location

MSVC output:

std.ixx
winrt_numerics.ixx
winrt_base.ixx
winrt.Windows.Foundation.ixx

GCC output when compiling winrt/winrt.Windows.Foundation.ixx:

In file included from winrt/winrt.Windows.Foundation.ixx:102:
./winrt/Windows.Foundation.h: In member function 'void winrt::when_any(const T&, const Rest& ...)::shared_type::operator()(const T&, winrt::Windows::Foundation::AsyncStatus)':
./winrt/Windows.Foundation.h:4217:32: error: there are no arguments to '_InterlockedCompareExchangePointer' that depend on a template parameter, so a declaration of '_InterlockedCompareExchangePointer' must be available [-Wtemplate-body]
 4217 |                 if (nullptr == _InterlockedCompareExchangePointer(reinterpret_cast<void**>(&result), sender_abi, nullptr))
      |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

g++ version:

g++ -v
Using built-in specs.
COLLECT_GCC=C:\Tools\msys64\ucrt64\bin\g++.exe
COLLECT_LTO_WRAPPER=C:/Tools/msys64/ucrt64/bin/../lib/gcc/x86_64-w64-mingw32/16.2.0/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../gcc-16.2.0/configure --prefix=/ucrt64 --with-sysroot=/ucrt64 --with-build-sysroot=D:/M/msys64/ucrt64 --with-local-prefix=/local --with-native-system-header-dir=/include --libexecdir=/ucrt64/lib --enable-bootstrap --enable-checking=release --with-arch=nocona --with-tune=generic --enable-mingw-wildcard --enable-languages=c,c++,ada,fortran,lto,objc,obj-c++,jit --enable-shared --enable-static --enable-libatomic --enable-threads=posix --enable-tls --enable-graphite --enable-fully-dynamic-string --enable-libstdcxx-backtrace=yes --enable-libstdcxx-filesystem-ts --enable-libstdcxx-time --disable-libstdcxx-pch --enable-libgomp --disable-libssp --disable-multilib --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-libiconv --with-system-zlib --with-gmp=/ucrt64 --with-mpfr=/ucrt64 --with-mpc=/ucrt64 --with-isl=/ucrt64 --with-pkgversion='Rev6, Built by MSYS2 project' --with-bugurl=https://github.com/msys2/MINGW-packages/issues --with-gnu-as --with-gnu-ld --with-libstdcxx-zoneinfo=yes --disable-libstdcxx-debug --enable-lto --enable-plugin --with-boot-ldflags=-static-libstdc++ --with-stage1-ldflags=-static-libstdc++
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.2.0 (Rev6, Built by MSYS2 project)

Additional comments

winrt_numerics.ixx includes <windowsnumerics.impl.h> directly inside its module purview after pre-including only <directxmath.h> in the global module fragment. However, <windowsnumerics.impl.h> transitively includes standard library headers (<stdexcept> and <limits> in the Windows SDK, and <algorithm> and <cmath> in mingw-w64) inside the module purview, which breaks module builds on libstdc++ and libc++. In addition, the DirectX interop functions (XMLoadFloat2, XMStoreFloat2, etc.) defined in <windowsnumerics.impl.h> sit outside _WINDOWS_NUMERICS_BEGIN_NAMESPACE_, leaving them unexported and attached to the winrt_numerics module even on MSVC.