`extern "C"` is not fully supported.

[BlueStaggo]

Bug type: Language Service

Describe the bug

• OS and Version: Windows 10 x64 1909
• VS Code Version: 1.58.2
• C/C++ Extension Version: 1.5.1
• Other extensions you installed (and if the issue persists after disabling them): C++ Intellisense (still persists without it)

extern "C" blocks are ok, but using it like this:

extern "C" void doSomething();

causes an error. However, this does not always happen, especially after compiling using a Makefile.

Steps to reproduce

1. Create a C++ header file.
2. Create an extern "C" function, such as the one shown above.

Expected behavior
This is valid C++, so it should not be treated as an error.

Code sample and logs

• Code sample

  • See the code above or the screenshot.

• Configurations in c_cpp_properties.json

  • I do not have this.

• Logs from running C/C++: Log Diagnostics from the VS Code command palette

-------- Diagnostics - 20/07/2021, 12:15:58
Version: 1.5.1
Current Configuration:
{
    "name": "Win32",
    "includePath": [
        "${workspaceFolder}/**"
    ],
    "defines": [
        "_DEBUG",
        "UNICODE",
        "_UNICODE"
    ],
    "windowsSdkVersion": "10.0.19041.0",
    "cStandard": "c17",
    "cppStandard": "c++17",
    "compilerArgs": [],
    "intelliSenseMode": "windows-gcc-x64",
    "intelliSenseModeIsExplicit": true,
    "cStandardIsExplicit": false,
    "cppStandardIsExplicit": false,
    "compilerPathIsExplicit": true,
    "compilerPath": "g++",
    "browse": {
        "path": [
            "${workspaceFolder}/**"
        ],
        "limitSymbolsToIncludedHeaders": true
    }
}
Translation Unit Mappings:
[ C:\Users\####\Programming\C++\OpenGL\Tutorial\src\main.c ]:
    C:\USERS\####\PROGRAMMING\C++\OPENGL\TUTORIAL\SRC\MAIN.C
    C:\USERS\####\PROGRAMMING\C++\OPENGL\TUTORIAL\INCLUDE\CONST.H
Translation Unit Configurations:
[ C:\Users\####\Programming\C++\OpenGL\Tutorial\src\main.c ]:
    Process ID: 14200
    Memory Usage: 13 MB
    Compiler Path: C:\msys64\mingw64\bin\g++.exe
    Includes:
        C:\MSYS64\MINGW64\LIB\GCC\X86_64-W64-MINGW32\10.2.0\INCLUDE
        C:\MSYS64\MINGW64\INCLUDE
        C:\MSYS64\MINGW64\LIB\GCC\X86_64-W64-MINGW32\10.2.0\INCLUDE-FIXED
        C:\MSYS64\MINGW64\X86_64-W64-MINGW32\INCLUDE
        C:\USERS\####\PROGRAMMING\C++\OPENGL\TUTORIAL\INCLUDE
    Defines:
        _DEBUG
        UNICODE
        _UNICODE
    Standard Version: c17
    IntelliSense Mode: windows-gcc-x64
    Other Flags:
        --gcc
        --gnu_version=100200
Total Memory Usage: 13 MB

------- Workspace parsing diagnostics -------
Number of files discovered (not excluded): 3839

• Logs from the language server logging
  • TL;DR: It says nothing about extern "C".

Screenshots

Additional context

None

[sean-mcmanus]

This is "by design". The ".c" extension is treated as C by default, which doesn't allow extern "C". Add "*.c": "cpp" to your files.associations setting to make ".c" files be treated as C++.

[BlueStaggo]

I must've run the logging on the wrong file by the look of it. Now, this issue does not persist, so no further discussion is required.