Intellisense forces the use of msvc LSP, no way to override the setting.

[esperanza-esperanza]

Environment

• OS and Version: Windows 11 x64 Pro 25H2
• VS Code Version: 1.101.5
• C/C++ Version: 1.28.3
• C/C++ Extension Version: 1.3.1
• Meson Extension Version: 1.27.0

Bug Summary and Steps to Reproduce

Bug Summary:
Possibly I used env var CC=clang-cl instead of clang-cl.exe.

Steps to reproduce:

1. Set the env var for CC/CXX to clang-cl/clang.
2. Create an example meson project.
3. Set intellisense to windows-clang-x64.
4. Intellisense cannot find clang-cl/clang.
5. Add clang-cl/clang to path.
6. Intellisense cannot find clang-cl/clang.
7. Provide direct compiler path and folder to the compiler path in C/C++ extension settings.
8. Intellisense cannot find clang-cl/clang.
9. Install clangd extension.
10. Intellisense prompts for disablement.
11. The compiler path is in PATH env varriable, clangd gets found. C:(...)\VC\Tools\Llvm\x64\bin
12. Some global setting gets set that stays when the extension gets disabled. LSP no longer is set to the MSVC LSP.

Expected behaviour:
LLVM-tools are installed from VS.
Therefore clang/clang-cl gets found without any fiddling when setting intellisense to the windows-clang-x64 setting.
PATH should get used as a fallback.
"C_Cpp.default.compilerPath" shouldn't get ignored or allow direct path to .exe.
Setting CC to clang-cl.exe doesn't do much

Configuration and Logs

Startup debug message:
Unable to resolve configuration with compilerPath "clang-cl.exe". Using "cl.exe" instead.

-------- Diagnostics - 11/11/2025, 11:36:26 AM
Version: 1.28.3
Current Configuration:
{
    "name": "Win32",
    "includePath": [
        "c:/Users/jakubby/Desktop/Code Projects/Graphics Scribble/Bicubic/**"
    ],
    "defines": [
        "_DEBUG",
        "UNICODE",
        "_UNICODE"
    ],
    "windowsSdkVersion": "10.0.26100.0",
    "cStandard": "c17",
    "cppStandard": "c++17",
    "compileCommands": [
        "c:\\Users\\jakubby\\Desktop\\Code Projects\\Graphics Scribble\\Bicubic\\build/compile_commands.json"
    ],
    "intelliSenseMode": "windows-clang-x64",
    "intelliSenseModeIsExplicit": true,
    "cStandardIsExplicit": false,
    "cppStandardIsExplicit": false,
    "mergeConfigurations": false,
    "recursiveIncludes": {},
    "recursiveIncludesReduceIsExplicit": false,
    "recursiveIncludesPriorityIsExplicit": false,
    "recursiveIncludesOrderIsExplicit": false,
    "compilerPathIsExplicit": false,
    "configurationProvider": "mesonbuild.mesonbuild",
    "browse": {
        "limitSymbolsToIncludedHeaders": true
    }
}
Modified Settings:
{
    "C_Cpp.default.compileCommands": "c:\\Users\\jakubby\\Desktop\\Code Projects\\Graphics Scribble\\Bicubic\\build/compile_commands.json",
    "C_Cpp.default.intelliSenseMode": "windows-clang-x64",
    "C_Cpp.default.compilerPath": "C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\Llvm\\x64\\bin",
    "C_Cpp.default.configurationProvider": "mesonbuild.mesonbuild"
}
Additional Tracked Settings:
{
    "editorTabSize": 4,
    "editorInsertSpaces": true,
    "editorAutoClosingBrackets": "languageDefined",
    "filesEncoding": "utf8",
    "filesAssociations": {},
    "filesExclude": {
        "**/.git": true,
        "**/.svn": true,
        "**/.hg": true,
        "**/.DS_Store": true,
        "**/Thumbs.db": true
    },
    "filesAutoSaveAfterDelay": false,
    "editorInlayHintsEnabled": true,
    "editorParameterHintsEnabled": true,
    "searchExclude": {
        "**/node_modules": true,
        "**/bower_components": true,
        "**/*.code-search": true
    },
    "workbenchSettingsEditor": "ui"
}
Custom browse configuration: 
{
    "browsePath": [
        ""
    ],
    "compilerPath": "clang-cl.exe",
    "compilerArgs": []
}
cpptools version (native): 1.28.3.0
Current database path: C:\USERS\JAKUBBY\APPDATA\LOCAL\MICROSOFT\VSCODE-CPPTOOLS\22EF692DF0D2A1A8F52301E9197AB384\.BROWSE.VC.DB
Translation Unit Mappings:
[ C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic\wack.c - source TU]:
Translation Unit Configurations:
[ C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic\wack.c ]
    Process ID: 3008
    Memory Usage: 204 MB
    Compiler Path: C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\bin\Hostx64\x64\cl.exe
    Include paths:
        include: C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic\build\wack.exe.p
        include: C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic\build
        include: C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic
        include: C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic\external\glad\include
        include: C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic\external\SDL2\include
        include: C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic\external\SDL2_image\include
        system include: C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\include
        system include: C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\atlmfc\include
        system include: C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\um
        system include: C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\ucrt
        system include: C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\shared
        system include: C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\winrt
        system include: C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\cppwinrt
    Standard Version: ms_c17
    IntelliSense Mode: windows-msvc-x64
    compile_commands.json entry:
        directory: C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic\build
        file: C:\USERS\JAKUBBY\DESKTOP\CODE PROJECTS\GRAPHICS SCRIBBLE\BICUBIC\WACK.C
        command: "clang-cl.exe" "-Iwack.exe.p" "-I." "-I.." "-I..\external\glad\include" "-I..\external\SDL2\include" "-I..\external\SDL2_image\include" "/MD" "/nologo" "/showIncludes" "/utf-8" "/W4" "/O2" "/Zi" "/Fdwack.exe.p\wack.c.pdb" /Fowack.exe.p/wack.c.obj "/c" ../wack.c
        output: wack.exe.p/wack.c.obj
Total Memory Usage: 204 MB
Browse Paths from compile_commands.json, from workspace folder: C:\Users\jakubby\Desktop\Code Projects\Graphics Scribble\Bicubic
    C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\cppwinrt
    C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\shared
    C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\ucrt
    C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\um
    C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\winrt
    C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\atlmfc\include
    C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\include

------- Workspace parsing diagnostics -------
Number of files discovered (not excluded): 5074

Other Extensions

• Meson Extension Version: 1.27.0
• clangd Extension Version: 0.2.0

Additional context

No response

[sean-mcmanus]

@esperanza-esperanza The compilerPath needs to be the full path and not just the path to the folder, can you try C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\Llvm\\x64\\bin\\clang-cl.exe?

[sean-mcmanus]

Also, the clang-cl.exe from the compile_commands.json and the configuration provider might need to be a full path. I don't think we process the CC/CXX environment variables.

[sean-mcmanus]

But we're supposed to detect clang-cl.exe if it's at C:\\Program Files\\Microsoft Visual Studio\\2022\\Community\\VC\\Tools\\Llvm\\x64\\bin.

I repro the bug. Having C:\Program Files\LLVM\bin\clang-cl.exe seems to work though.

[sean-mcmanus]

But using the full path works, it looks like we never supported "clang-cl.exe" without a path like for "cl.exe", oh wait the code is there, something must be causing it to be skipped or not hit (or that might just be for when searching for the default compiler and not for resolving an existing one, I'll check later...). UPDATE: Yeah, "clang-cl.exe" doesn't automatically resolve to the one installed by VS like using "cl.exe" does. It needs to have the it on the PATH somehow.

[sean-mcmanus]

@esperanza-esperanza It works for me when I launch VS Code from the developer command prompt with the clang-cl.exe installed.

[sean-mcmanus]

@esperanza-esperanza Yeah, clang-cl.exe should be found if it's on your PATH -- that's what I'm seeing.