目标平台为 Windows 时 Clang 工具链不主动加载 MSVC 编译环境

[Doekin]

Xmake 版本

xmake v2.9.6+HEAD.abd15c255

操作系统版本和架构

Windows 10

描述问题

使用 Clang 工具链（LLVM-MinGW）为 Windows 平台构建程序，出现找不到标准库头文件的错误

fatal error: 'stdio.h' file not found
    1 | #include <stdio.h>
      |          ^~~~~~~~~

而在 Developer PowerShell 中执行 clang -m64 --target=x86_64-windows-msvc src\hello.c 可以正常编译

期待的结果

使用 Clang 工具链时，能主动加载 MSVC 环境（类似使用 MSVC 工具链时 XMake 的行为）

工程配置

$ xmake f -c -vD --toolchain=clang
$ xmake -r -vD hello_c

附加信息和错误日志

诊断日志

checking for clang ... ok
checking for the c compiler (cc) ... clang
checking for flags (-O3) ... ok
> clang "-O3" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-DNDEBUG) ... ok
> clang "-DNDEBUG" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for clang ... ok
checking for the c++ compiler (cxx) ... clang
[ 50%]: cache compiling.release src\hello.c
clang -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -fvisibility=hidden -O3 -DNDEBUG -o build\.objs\hello_c\windows\x64\release\src\hello.c.obj src\hello.c
checking for flags (-MMD -MF) ... ok
> clang "-MMD" "-MF" "C:\Users\leemu\AppData\Local\Temp\.xmake\241216\_2C63DED93CDF473082B0786F9FF45880" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-fdiagnostics-color=always) ... ok
> clang "-fdiagnostics-color=always" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-fansi-escape-codes) ... ok
> clang "-fansi-escape-codes" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-Wno-gnu-line-marker -Werror) ... ok
> clang "-Wno-gnu-line-marker" "-Werror" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
error: @programdir\core\main.lua:329: @programdir\actions\build\main.lua:148: @programdir\modules\async\runjobs.lua:325: @programdir\modules\private\action\build\object.lua:91: @programdir\modules\core\tools\gcc.lua:966: src\hello.c:1:10:
 fatal error: 'stdio.h' file not found
    1 | #include <stdio.h>
      |          ^~~~~~~~~
1 error generated.
stack traceback:
    [C]: in function 'error'
    [@programdir\core\base\os.lua:1004]:
    [@programdir\modules\core\tools\gcc.lua:966]: in function 'catch'
    [@programdir\core\sandbox\modules\try.lua:123]: in function 'try'
    [@programdir\modules\core\tools\gcc.lua:907]:
    [C]: in function 'xpcall'
    [@programdir\core\base\utils.lua:244]:
    [@programdir\core\tool\compiler.lua:288]: in function 'compile'
    [@programdir\modules\private\action\build\object.lua:91]: in function 'script'
    [@programdir\modules\private\action\build\object.lua:122]: in function 'build_object'
    [@programdir\modules\private\action\build\object.lua:147]: in function 'jobfunc'
    [@programdir\modules\async\runjobs.lua:241]:
    [C]: in function 'xpcall'
    [@programdir\core\base\utils.lua:244]: in function 'trycall'
    [@programdir\core\sandbox\modules\try.lua:117]: in function 'try'
    [@programdir\modules\async\runjobs.lua:223]: in function 'cotask'
    [@programdir\core\base\scheduler.lua:406]:

stack traceback:
        [C]: in function 'error'
        @programdir\core\base\os.lua:1004: in function 'base/os.raiselevel'
        (...tail calls...)
        @programdir\core\main.lua:329: in upvalue 'cotask'
        @programdir\core\base\scheduler.lua:406: in function <@programdir\core\base\scheduler.lua:399>

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

---

Title: When the target platform is Windows, the Clang tool chain does not actively load the MSVC compilation environment

[Doekin]

Update

Clang 在目标平台为 Windows 时，是会加载 MSVC 环境变量的，只是不知道为什么，似乎不太管用

xmake/xmake/toolchains/clang/load.lua

Lines 67 to 85 in bd09a63

	if toolchain:is_plat("windows") then
	target = target .. "-windows-msvc"
	-- add vs environments
	local expect_vars = {"PATH", "LIB", "INCLUDE", "LIBPATH"}
	local curenvs = os.getenvs()
	for _, name in ipairs(expect_vars) do
	_add_vsenv(toolchain, name, curenvs)
	end
	for _, name in ipairs(find_vstudio.get_vcvars()) do
	if not table.contains(expect_vars, name:upper()) then
	_add_vsenv(toolchain, name, curenvs)
	end
	end
	if is_host("linux") then
	toolchain:add("ldflags", "-fuse-ld=lld-link" .. suffix)
	toolchain:add("shflags", "-fuse-ld=lld-link" .. suffix)
	end

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

---

Update

Clang will load the MSVC environment variable when the target platform is Windows, but I don’t know why and it doesn’t seem to work.

xmake/xmake/toolchains/clang/load.lua

Lines 67 to 85 in bd09a63

	if toolchain:is_plat("windows") then
	target = target .. "-windows-msvc"
	-- add vs environments
	local expect_vars = {"PATH", "LIB", "INCLUDE", "LIBPATH"}
	local curenvs = os.getenvs()
	for _, name in ipairs(expect_vars) do
	_add_vsenv(toolchain, name, curenvs)
	end
	for _, name in ipairs(find_vstudio.get_vcvars()) do
	if not table.contains(expect_vars, name:upper()) then
	_add_vsenv(toolchain, name, curenvs)
	end
	end
	if is_host("linux") then
	toolchain:add("ldflags", "-fuse-ld=lld-link" .. suffix)
	toolchain:add("shflags", "-fuse-ld=lld-link" .. suffix)
	end

[star-hengxing]

可以 add_cxflags("-v") 看看搜索路径

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

---

You can add_cxflags("-v") to see the search path

[Doekin]

xmake f -c -vD --toolchain=clang

checking for platform ... windows
checking for architecture ... x64
checking for clang ... ok
checking for clang++ ... ok
checking for the linker (ld) ... clang++
checking for clang++ ... ok
checking for the shared library linker (sh) ... clang++
configure
{
    mingw = D:/Applications/Scoop/apps/mingw-mstorsjo-llvm-ucrt/current/
    network = public
    proxy = socks5://127.0.0.1:20170
    ccache = true
    buildir = build
    toolchain = clang
    arch = x64
    mode = release
    kind = static
    clean = true
    proxy_pac = pac.lua
    ndk_stdcxx = true
    host = windows
    theme = default
    plat = windows
}

xmake -r -vD hello_c

checking for clang ... ok
checking for the c compiler (cc) ... clang
checking for flags (-O3) ... ok
> clang "-O3" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-v) ... ok
> clang "-v" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-DNDEBUG) ... ok
> clang "-DNDEBUG" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for clang ... ok
checking for the c++ compiler (cxx) ... clang
[ 50%]: cache compiling.release src\hello.c
clang -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -fvisibility=hidden -O3 -v -DNDEBUG -o build\.objs\hello_c\windows\x64\release\src\hello.c.obj src\hello.c
checking for flags (-MMD -MF) ... ok
> clang "-MMD" "-MF" "C:\Users\leemu\AppData\Local\Temp\.xmake\241217\_A3ADF10C90344B60830345B334841170" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-fdiagnostics-color=always) ... ok
> clang "-fdiagnostics-color=always" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-fansi-escape-codes) ... ok
> clang "-fansi-escape-codes" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
checking for flags (-Wno-gnu-line-marker -Werror) ... ok
> clang "-Wno-gnu-line-marker" "-Werror" "-Qunused-arguments" "-m64" "--target=x86_64-windows-msvc"
error: @programdir\core\main.lua:329: @programdir\actions\build\main.lua:148: @programdir\modules\async\runjobs.lua:325: @programdir\modules\private\action\build\object.lua:91: @programdir\modules\core\tools\gcc.lua:966: clang version 19.1.5 (https://github.com/llvm/llvm-project.git ab4b5a2db582958af1ee308a790cfdb42bd24720)
Target: x86_64-unknown-windows-msvc
Thread model: posix
InstalledDir: D:/Applications/Scoop/apps/mingw-mstorsjo-llvm-ucrt/19.1.5-20241203/bin
 (in-process)
 "D:/Applications/Scoop/apps/mingw-mstorsjo-llvm-ucrt/19.1.5-20241203/bin/clang-19.exe" -cc1 -triple x86_64-unknown-windows-msvc19.33.0 -emit-obj -mincremental-linker-compatible -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name hello.c 
-mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -fdebug-compilation-dir=D:/projects/cpp-playground -v -fcoverage-compilation-dir=D:/projects/cpp-playground -resource-dir D:/Applications/Scoop/apps/mingw-mstorsjo-llvm-ucrt/19.1.5-20241203/lib/clang/19 -dependency-file "C:\\Users\\leemu\\AppData\\Local\\Temp\\.xmake\\241217\\_0E60883D424248308CAA376A3578D1B0" -MT "build\\.objs\\hello_c\\windows\\x64\\release\\src\\hello.c.obj" -D NDEBUG -internal-isystem D:/Applications/Scoop/apps/mingw-mstorsjo-llvm-ucrt/19.1.5-20241203/lib/clang/19/include -internal-isystem "C:/Program Files/Microsoft Visual Studio 10.0/VC/include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 9.0/VC/include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 9.0/VC/PlatformSDK/Include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 8/VC/include" -internal-isystem "C:/Program Files/Microsoft Visual Studio 8/VC/PlatformSDK/Include" -O3 -ferror-limit 19 -fvisibility=hidden -fno-use-cxa-atexit -fms-extensions -fms-compatibility -fms-compatibility-version=19.33 -fskip-odr-check-in-gmf -fdelayed-template-parsing -fcolor-diagnostics -fansi-escape-codes -vectorize-loops -vectorize-slp -faddrsig -o "build\\.objs\\hello_c\\windows\\x64\\release\\src\\hello.c.obj" 
-x c "src\\hello.c"
clang -cc1 version 19.1.5 based upon LLVM 19.1.5 default target x86_64-w64-mingw32
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 10.0/VC/include"
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 9.0/VC/include"
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 9.0/VC/PlatformSDK/Include"
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 8/VC/include"
ignoring nonexistent directory "C:/Program Files/Microsoft Visual Studio 8/VC/PlatformSDK/Include"
#include "..." search starts here:
#include <...> search starts here:
 D:/Applications/Scoop/apps/mingw-mstorsjo-llvm-ucrt/19.1.5-20241203/lib/clang/19/include
End of search list.
src\hello.c:1:10: fatal error: 'stdio.h' file not found
    1 | #include <stdio.h>
      |          ^~~~~~~~~
1 error generated.
stack traceback:
    [C]: in function 'error'
    [@programdir\core\base\os.lua:1004]:
    [@programdir\modules\core\tools\gcc.lua:966]: in function 'catch'
    [@programdir\core\sandbox\modules\try.lua:123]: in function 'try'
    [@programdir\modules\core\tools\gcc.lua:907]:
    [C]: in function 'xpcall'
    [@programdir\core\base\utils.lua:244]:
    [@programdir\core\tool\compiler.lua:288]: in function 'compile'
    [@programdir\modules\private\action\build\object.lua:91]: in function 'script'
    [@programdir\modules\private\action\build\object.lua:122]: in function 'build_object'
    [@programdir\modules\private\action\build\object.lua:147]: in function 'jobfunc'
    [@programdir\modules\async\runjobs.lua:241]:
    [C]: in function 'xpcall'
    [@programdir\core\base\utils.lua:244]: in function 'trycall'
    [@programdir\core\sandbox\modules\try.lua:117]: in function 'try'
    [@programdir\modules\async\runjobs.lua:223]: in function 'cotask'
    [@programdir\core\base\scheduler.lua:406]:

stack traceback:
        [C]: in function 'error'
        @programdir\core\base\os.lua:1004: in function 'os.raiselevel'
        (...tail calls...)
        @programdir\core\main.lua:329: in upvalue 'cotask'
        @programdir\core\base\scheduler.lua:406: in function <@programdir\core\base\scheduler.lua:399>

[Doekin]

xmake/xmake/toolchains/clang/load.lua

Lines 67 to 85 in bd09a63

	if toolchain:is_plat("windows") then
	target = target .. "-windows-msvc"
	-- add vs environments
	local expect_vars = {"PATH", "LIB", "INCLUDE", "LIBPATH"}
	local curenvs = os.getenvs()
	for _, name in ipairs(expect_vars) do
	_add_vsenv(toolchain, name, curenvs)
	end
	for _, name in ipairs(find_vstudio.get_vcvars()) do
	if not table.contains(expect_vars, name:upper()) then
	_add_vsenv(toolchain, name, curenvs)
	end
	end
	if is_host("linux") then
	toolchain:add("ldflags", "-fuse-ld=lld-link" .. suffix)
	toolchain:add("shflags", "-fuse-ld=lld-link" .. suffix)
	end

在这段代码后面用 toolchain:get("runenvs") 或者 toolchain:config("runenvs") ，打印出来 runenvs 都是 nil

可能是 check 时没添加到

xmake/xmake/toolchains/clang/check.lua

Lines 58 to 69 in a2ee23e

	function main(toolchain, suffix)
	-- only for windows or linux (msvc-wine)
	if not is_host("windows", "linux") then
	return
	end
	local sdkdir = toolchain:sdkdir()
	if sdkdir then
	return _check_vc_build_tools(toolchain, sdkdir, suffix)
	end
	end

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

---

xmake/xmake/toolchains/clang/load.lua

Lines 67 to 85 in bd09a63

	if toolchain:is_plat("windows") then
	target = target .. "-windows-msvc"
	-- add vs environments
	local expect_vars = {"PATH", "LIB", "INCLUDE", "LIBPATH"}
	local curenvs = os.getenvs()
	for _, name in ipairs(expect_vars) do
	_add_vsenv(toolchain, name, curenvs)
	end
	for _, name in ipairs(find_vstudio.get_vcvars()) do
	if not table.contains(expect_vars, name:upper()) then
	_add_vsenv(toolchain, name, curenvs)
	end
	end
	if is_host("linux") then
	toolchain:add("ldflags", "-fuse-ld=lld-link" .. suffix)
	toolchain:add("shflags", "-fuse-ld=lld-link" .. suffix)
	end

Use toolchain:get("runenvs") or toolchain:config("runenvs") after this code, and the printed runenvs will be nil

It may be that it was not added during check.

xmake/xmake/toolchains/clang/check.lua

Lines 58 to 69 in a2ee23e

	function main(toolchain, suffix)
	-- only for windows or linux (msvc-wine)
	if not is_host("windows", "linux") then
	return
	end
	local sdkdir = toolchain:sdkdir()
	if sdkdir then
	return _check_vc_build_tools(toolchain, sdkdir, suffix)
	end
	end

I did not specify sdk, and sdkdir was printed as nil

[Doekin]

或许可以模仿 clang-cl 工具链的做法，寻找 vs 并添加相关环境变量

xmake/xmake/toolchains/clang-cl/check.lua

Lines 140 to 171 in 70eb7bb

	function main(toolchain)
	-- only for windows or linux (msvc-wine)
	if not is_host("windows", "linux") then
	return
	end
	-- @see https://github.com/xmake-io/xmake/pull/679
	local cc = path.basename(config.get("cc") or "clang-cl"):lower()
	local cxx = path.basename(config.get("cxx") or "clang-cl"):lower()
	local mrc = path.basename(config.get("mrc") or "rc"):lower()
	if cc == "clang-cl" or cxx == "clang-cl" or mrc == "rc" then
	local sdkdir = toolchain:sdkdir()
	if sdkdir then
	return _check_vc_build_tools(toolchain, sdkdir)
	else
	-- find it from packages
	for _, package in ipairs(toolchain:packages()) do
	local installdir = package:installdir()
	if installdir and os.isdir(installdir) then
	local result = _check_vc_build_tools(toolchain, installdir)
	if result then
	return result
	end
	end
	end
	-- find it from system
	return _check_vstudio(toolchain)
	end
	end
	end

我将上面这段复制给 clang 的 check：

xmake/xmake/toolchains/clang/check.lua

Lines 58 to 69 in a2ee23e

	function main(toolchain, suffix)
	-- only for windows or linux (msvc-wine)
	if not is_host("windows", "linux") then
	return
	end
	local sdkdir = toolchain:sdkdir()
	if sdkdir then
	return _check_vc_build_tools(toolchain, sdkdir, suffix)
	end
	end

可以编译本地项目

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

---

Specifying sdkdir does not work either. In _check_vc_build_tools, vcvarsall prints out nil

xmake/xmake/toolchains/clang/check.lua

Lines 25 to 31 in a2ee23e

	function _check_vc_build_tools(toolchain, sdkdir, suffix)
	local opt = {}
	opt.sdkdir = sdkdir
	opt.vs_toolset = toolchain:config("vs_toolset") or config.get("vs_toolset")
	opt.vs_sdkver = toolchain:config("vs_sdkver") or config.get("vs_sdkver")
	local vcvarsall = find_vstudio.find_build_tools(opt)

The possible reason is that the installation path of Visual Studio Build Tools 2022 is different from the default one.

xmake/xmake/modules/detect/sdks/find_vstudio.lua

Lines 102 to 139 in a2ee23e

	function find_build_tools(opt)
	opt = opt or {}
	local sdkdir = opt.sdkdir
	if not sdkdir or not os.isdir(sdkdir) then
	return
	end
	local variables = {}
	local VCToolsVersion
	local vs_toolset = opt.vs_toolset
	if vs_toolset and os.isdir(path.join(sdkdir, "VC/Tools/MSVC", vs_toolset)) then
	VCToolsVersion = vs_toolset
	else
	local dir = find_directory("14*", path.join(sdkdir, "VC/Tools/MSVC"))
	if dir then
	VCToolsVersion = path.filename(dir)
	else
	return
	end
	end
	variables.VCToolsVersion = VCToolsVersion
	variables.VCToolsInstallDir = path.join(sdkdir, "VC/Tools/MSVC", VCToolsVersion)
	local WindowsSDKVersion
	local vs_sdkver = opt.vs_sdkver
	if vs_sdkver and os.isdir(path.join(sdkdir, "Windows Kits/10/Lib", vs_sdkver)) then
	WindowsSDKVersion = vs_sdkver
	else
	local dir = find_directory("10*", path.join(sdkdir, "Windows Kits/10/Lib"))
	if dir then
	WindowsSDKVersion = path.filename(dir)
	else
	return
	end
	end
	variables.WindowsSDKVersion = WindowsSDKVersion
	variables.WindowsSdkDir = path.join(sdkdir, "Windows Kits/10")

On my computer, sdkdir is set to C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\ and VCToolsInstallDir is C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\VC\Tools\MSVC\14.42.34433, WindowsSdkDir is C:\Program Files (x86)\Windows Kits\10\

[waruqi]

Clang 在目标平台为 Windows 时，是会加载 MSVC 环境变量的，只是不知道为什么，似乎不太管用

目前 clang 那个 toolchain ，check 阶段仅仅做了 portable build msvc 的支持，不会去检测加载系统 vs 环境。

只有 clang-cl 的才会。

xmake/xmake/toolchains/clang-cl/check.lua

Line 168 in 323eb11

return _check_vstudio(toolchain)

另外，即使 clang toolchain 不加载 msvc ，也是可以正常编译的。

xmake f --toolchain=clang -c; xmake -rv
checking for platform ... windows
checking for architecture ... x64
checking for clang ... ok
checking for the c compiler (cc) ... clang
checking for flags (-O3) ... ok
checking for flags (-DNDEBUG) ... ok
checking for clang ... ok
checking for the c++ compiler (cxx) ... clang
[ 50%]: cache compiling.release src\main.c
clang -c -Qunused-arguments -m64 --target=x86_64-windows-msvc -fvisibility=hidden -O3 -DNDEBUG -o build\.objs\test\windows\x64\release\src\main.c.obj src\main.c
checking for flags (-MMD -MF) ... ok
checking for flags (-fdiagnostics-color=always) ... ok
checking for flags (-fansi-escape-codes) ... ok
checking for flags (-Wno-gnu-line-marker -Werror) ... ok
[ 75%]: linking.release test.exe
clang++ -o build\windows\x64\release\test.exe build\.objs\test\windows\x64\release\src\main.c.obj -m64 --target=x86_64-windows-msvc
[100%]: build ok, spent 1.766s

而且 llvm/clang 原本就不应该跟 msvc 两套环境强耦合绑定。它本就是独立的工具链，有自己的 libc++ 头文件，干嘛默认要跟 msvc 耦合在一起？除非显式指定 要用 msvc 的

[Doekin]

对哦，我一时没转过弯来，想得不够周到
谢谢解答

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

---

That's right, I didn't turn around for a moment and didn't think carefully enough.
Thanks for the answer