[IntelliSense C] The "defined" operator is not correctly interpreted by #if

Environment

• OS and Version: Windows 10 Entreprise 22H2
• VS Code Version: 1.86.1
• C/C++ Extension Version: 1.18.5

Bug Summary and Steps to Reproduce

​The VSCode editor doesn't seem to interpret #if statements correctly when using the special operator "defined"

Example with the following code:

#define A_DEFINED_VARIABLE          1

#define CHECK_A_DEFINED_VARIABLE    (defined(A_DEFINED_VARIABLE))

#if (defined(A_DEFINED_VARIABLE))
static int MyVar1 = 1;
#endif

#if CHECK_A_DEFINED_VARIABLE
static int MyVar2 = 2;
#endif

int main()
{
    return MyVar1 + MyVar2;
}

IntelliSense considers that MyVar1 is defined, but not MyVar2.

Configuration and Logs

-------- Diagnostics - 2/13/2024, 2:50:33 PM
Version: 1.18.5
Current Configuration:
{
    "name": "Win32",
    "includePath": [
        "${workspaceFolder}/**"
    ],
    "defines": [
        "_DEBUG",
        "UNICODE",
        "_UNICODE"
    ],
    "windowsSdkVersion": "10.0.22621.0",
    "compilerPath": "cl.exe",
    "cStandard": "c17",
    "cppStandard": "c++17",
    "intelliSenseMode": "windows-msvc-x64",
    "compilerPathInCppPropertiesJson": "cl.exe",
    "intelliSenseModeIsExplicit": false,
    "cStandardIsExplicit": false,
    "cppStandardIsExplicit": false,
    "mergeConfigurations": false,
    "compilerPathIsExplicit": false,
    "browse": {
        "path": [
            "${workspaceFolder}/**"
        ],
        "limitSymbolsToIncludedHeaders": true
    }
}
cpptools version (native): 1.18.3.0
Translation Unit Mappings:
[ C:\Data\Tmp\test.c ]:
    C:\Data\Tmp\test.c
Translation Unit Configurations:
[ C:\Data\Tmp\test.c ]:
    Process ID: 26476
    Memory Usage: 49 MB
    Compiler Path: C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.38.33130\bin\Hostx64\x64\cl.exe
    Includes:
        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.38.33130\include
        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.38.33130\atlmfc\include
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\um
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\ucrt
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\shared
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\winrt
        C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\cppwinrt
    Defines:
        _DEBUG
        UNICODE
        _UNICODE
    Standard Version: ms_c17
    IntelliSense Mode: windows-msvc-x64
Total Memory Usage: 49 MB

------- Workspace parsing diagnostics -------
Number of files discovered (not excluded): 5027

Other Extensions

No response

Additional context

No response

Inizia riproducendo il problema con lo snippet C nel report usando le versioni elencate di VS Code e dell’estensione C/C++, quindi esamina la preelaborazione di IntelliSense di defined all’interno di una macro usata da #if. Il lavoro è completato quando MyVar2 viene riconosciuto in modo coerente con MyVar1 quando CHECK_A_DEFINED_VARIABLE si espande nell’espressione defined.