compilerPath with full path to cl.exe is not used - default cl.exe location is used instead.

[0xabu]

Type: LanguageService

Describe the bug

• OS and Version: Windows 20H2
• VS Code Version: 1.52.1
• C/C++ Extension Version: 1.1.3

I am trying in every possible way to tell the extension to use a locally-installed MSVC instance, but it persists in picking up the GCC from WSL. This is a regression, but when in the last few months it started I can't tell you exactly.

global settings.json has:

    "C_Cpp.default.compilerPath": "",

Workspace settings.json has:

    "C_Cpp.default.compilerPath": "C:\\NugetCache\\.A\\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\\lib\\native\\bin\\x86_amd64\\CL.exe",

c_cpp_properties.json:

{
    "configurations": [
        {
            "name": "Win32 Guest",
            "compileCommands": "${workspaceFolder}/compile_commands.json",
            "compilerPath": "C:\\NugetCache\\.A\\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\\lib\\native\\bin\\x86_amd64\\CL.exe",
            "intelliSenseMode": "msvc-x64"
        },
        ...
    ],
    "version": 4
}

compile_commands.json is autogenerated and includes commands pointing to the same CL.exe, e.g.:

{"directory": "C:\\src\\xxx\\Tests\\AsyncIO",
 "command": "C:\\NugetCache\\.A\\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\\lib\\native\\bin\\x86_amd64\\CL.exe /c ...",
 "file": "xxx.cpp"},

However, the extension persists in trying to use GCC, and consequently ends up with broken defines, includes, etc. See log output below.

Expected behavior
Use my configured cl.exe and don't even look for gcc!

Logs

cpptools/didChangeCppProperties
MSVC intelliSenseMode specified.  Configuring for compiler cl.exe.
Unable to configure for compiler cl.exe.
Attempting to get defaults from compiler found on the machine: '/usr/bin/gcc'
Compiler probe command line: "/usr/bin/gcc" -std=gnu11 -Wp,-v -E -dD -x c -m64  nul
Failed to spawn process. Error: 2 (The system cannot find the file specified.)
  WSL compiler detected
Compiler include path not found: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\End of search list.
Code browsing service initialized
MSVC intelliSenseMode specified.  Configuring for compiler cl.exe.
Unable to configure for compiler cl.exe.
Attempting to get defaults from compiler found on the machine: '/usr/bin/gcc'
Compiler probe command line: "/usr/bin/gcc" -std=gnu++14 -Wp,-v -E -dD -x c++ -m64  nul
Failed to spawn process. Error: 2 (The system cannot find the file specified.)
  WSL compiler detected
Compiler include path not found: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\End of search list.
MSVC intelliSenseMode specified.  Configuring for compiler cl.exe.
Unable to configure for compiler cl.exe.
Attempting to get defaults from compiler found on the machine: '/usr/bin/gcc'
MSVC intelliSenseMode specified.  Configuring for compiler cl.exe.
Unable to configure for compiler cl.exe.
Attempting to get defaults from compiler found on the machine: '/usr/bin/gcc'

(above 3 messages repeat hundreds of times)

  Folder: C:/Users/baumann/AppData/Local/Packages/CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc/LocalState/rootfs/usr/include/ will be indexed
  Folder: C:/Users/baumann/AppData/Local/Packages/CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc/LocalState/rootfs/usr/lib/gcc/x86_64-linux-gnu/7/include/ will be indexed
  Folder: C:/Users/baumann/AppData/Local/Packages/CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc/LocalState/rootfs/usr/lib/gcc/x86_64-linux-gnu/7/include-fixed/ will be indexed
  Folder: C:/Users/baumann/AppData/Local/Packages/CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc/LocalState/rootfs/usr/local/include/ will be indexed
  Folder: C:/NugetCache/.A/VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g/lib/native/include/ will be indexed
  ...
(remaining folders that should be indexed are listed, but note the system includes from WSL should *not* be here)

sending compilation args for xxx.cpp
  ...
  (my project's include paths)
  include: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\usr\include\c++\7
  include: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\usr\include\x86_64-linux-gnu\c++\7
  include: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\usr\include\c++\7\backward
  include: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\usr\lib\gcc\x86_64-linux-gnu\7\include
  include: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\usr\local\include
  include: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\usr\lib\gcc\x86_64-linux-gnu\7\include-fixed
  include: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\usr\include\x86_64-linux-gnu
  include: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\usr\include
  define: __STDC__=1
  define: __cplusplus=201402L
  define: __STDC_UTF_16__=1
  define: __STDC_UTF_32__=1
  define: __STDC_HOSTED__=1
  define: __GNUC__=7
  define: __GNUC_MINOR__=5
  define: __GNUC_PATCHLEVEL__=0
  ...

(obviously these defines/includes are all wrong)

Screenshots

Additional context

[Colengms]

Hi Andrew Baumann (@0xabu) . It looks like there is a bug handling the path to cl.exe that only occurs when it specified via compilerPath.

Does this work as expected if you remove both settings of C_Cpp.default.compilerPath, and remove the compilerPath from the config? Generally, use of compileCommands (or configurationProvider) take precedence over other config values, however compilerPath will take precedence over compileCommands (based on feedback from users who have wanted to override the compiler used by compile_commands.json). Having the compiler path specified only by compile_commands.json seems to work-around the issue. Let me know if you can confirm.

I'll use this bug to track fixing lookup of cl.exe when set via compilerPath.

[0xabu]

That seems to have made things worse. Now the extension is producing a huge log of repeated attempts to pass MSVC arguments to GCC:

Attempting to get defaults from C compiler in compile_commands.json file: 'C:\NugetCache\.A\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\lib\native\bin\x86_amd64\CL.exe'
MSVC intelliSenseMode specified.  Configuring for compiler cl.exe.
Unable to configure for compiler cl.exe.
Attempting to get defaults from compiler found on the machine: '/usr/bin/gcc'
Compiler probe command line: "/usr/bin/gcc" /c /Z7 /nologo /W4 /WX /diagnostics:column /Od /X /GF /Gm- /RTC1 /Zp8 /GS /Gy /fp:precise /Zc:wchar_t- /Zc:forScope /Zc:inline (...)
Failed to spawn process. Error: 2 (The system cannot find the file specified.)
Failed to query compiler. Falling back to 32-bit intelliSenseMode.
Compiler probe command line: "/usr/bin/gcc" /c /Z7 /nologo /W4 /WX /diagnostics:column /Od /X /GF /Gm- /RTC1 /Zp8 /GS /Gy /fp:precise /Zc:wchar_t- /Zc:forScope /Zc:inline (...)
Failed to spawn process. Error: 2 (The system cannot find the file specified.)
Failed to query compiler. Falling back to no bitness.
Compiler probe command line: "/usr/bin/gcc" /c /Z7 /nologo /W4 /WX /diagnostics:column /Od /X /GF /Gm- /RTC1 /Zp8 /GS /Gy /fp:precise /Zc:wchar_t- /Zc:forScope /Zc:inline (...)
Failed to spawn process. Error: 2 (The system cannot find the file specified.)
gcc: error: /c: No such file or directory
gcc: error: /Z7: No such file or directory
gcc: error: /nologo: No such file or directory
gcc: error: /W4: No such file or directory
...
No suitable compiler found. Please set the "compilerPath" in c_cpp_properties.json.

[Colengms]

Hi Andrew Baumann (@0xabu) . I gather you don't have an instance of MSVC installed via the Visual Studio installer, correct?

If a full path to cl.exe is specified, we will attempt to locate system include paths in relative locations. Specifically, it looks 3 directories up, and looks for include and atlmfc/include. Do you have C:\NugetCache\.A\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\include\lib ? If it fails to find one of these, it will fail to configure for cl.exe, and will attempt to fall back to whatever compiler it finds on your system.

I guess we're assuming the same layout as the VS installer. Are your system includes somewhere else?

[0xabu]

That's correct, I do not have Visual Studio etc. installed. But this is a perfectly functional MSVC.

The MSVC comes from an internal (I'll send you the link OOB) nuget of VisualCppTools, and the includes you're looking for appear to be at C:\NugetCache\.A\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\lib\native\include and C:\NugetCache\.A\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\lib\native\atlmfc

[Colengms]

Andrew Baumann (@0xabu) , I think it would be reasonable for us to add a check for includes at those relative location as well. Can you confirm that is the only remaining problem, by copying include and atlmfc to C:\NugetCache\.A\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\lib\, to see if cl.exe is detected properly?

[0xabu]

I copied {include,atlmfc} folders up to both C:\NugetCache\.A\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\lib and also C:\NugetCache\.A\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g (per your original comment of walking up 4 levels) but it doesn't seem to have made any difference to the failure :(

Is there anything I can do to get more debug output for "Unable to configure for compiler cl.exe"?

MSVC intelliSenseMode specified.  Configuring for compiler cl.exe.
Unable to configure for compiler cl.exe.
Attempting to get defaults from compiler found on the machine: '/usr/bin/gcc'
Compiler probe command line: "/usr/bin/gcc" -std=gnu++14 -Wp,-v -E -dD -x c++ -m64  nul
Failed to spawn process. Error: 2 (The system cannot find the file specified.)
  WSL compiler detected
Compiler include path not found: C:\Users\baumann\AppData\Local\Packages\CanonicalGroupLimited.Ubuntu18.04onWindows_79rhkp1fndgsc\LocalState\rootfs\End of search list.
Attempting to get defaults from C compiler in compile_commands.json file: 'C:\NugetCache\.A\VisualCppTools.jysOK2m_XNGtcXqE_1Xr3g\lib\native\bin\x86_amd64\cl.exe'
MSVC intelliSenseMode specified.  Configuring for compiler cl.exe.
Unable to configure for compiler cl.exe.
Attempting to get defaults from compiler found on the machine: '/usr/bin/gcc'

[pelco]

Hi Colen Garoutte-Carson (@Colengms) I'm having a similar issue, since I updated 1.2.0-insiders the compilerPath in the c_cpp_properties.json doesn't find the compiler, which is in my PATH, Output from C/C++ Warnings:

[15/01/2021, 14:14:45] Unable to resolve configuration with compilerPath "arm-openwrt-linux-gcc".  Using "/usr/bin/clang" instead.
[15/01/2021, 14:14:45] Unable to resolve configuration with compilerPath "arm-openwrt-linux-gcc".  Using "/usr/bin/clang" instead.

Not sure if it was fixed in 1.2.0.