Changing header file to C instead of C++ immediately reverts back to C++.

[CynicatPro]

Type: Bug

Changing header file to C instead of C++ immediately reverts back to C++.

I have a math library and i want to flip back and forth to test that it compiles in both C and C++ (yes, i'm doing full compile tests as well, but this is a quick smoke test).

When i click on the language select in the bottom right and change the language to C from C++, it immediately reverts back to C++.

Extension version: 1.22.10
VS Code version: Code 1.94.2 (384ff7382de624fb94dbaf6da11977bba1ecd427, 2024-10-09T16:08:44.566Z)
OS version: Windows_NT x64 10.0.19045
Modes:

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-9700K CPU @ 3.60GHz (8 x 3600)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	15.91GB (0.85GB free)
Process Argv	--crash-reporter-id f23e84c0-a32c-430f-a578-0707fe5c8de2
Screen Reader	no
VM	0%

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[sean-mcmanus]

@CynicatPro Can you run C/C++: Log Diagnostics, see what source file is being associated with the header, and then change the language of the source file from C++ to C, then open the header and right-click and select Reset IntelliSense for Active
File?

[CynicatPro]

Did that process, got a giant log printout, it stays on C only until I hit a key or save the file.

Oh wow, does it assume the mapping based on whether you include it in a .cpp/.cc file?

The "Translation Unit Mappings" include a 'game.cc' file as the file that includes it.

That makes a degree of sense but it is surprising.

[Colengms]

Hi @CynicatPro . I believe what you're seeing is a result of headers getting associated with source files (for various reasons, one of which is because custom configuration providers generally provide configurations for source files and not header files). What you're seeing is the header file's language association getting 'corrected' to refer to the language it's actually being processed as (based on the source file).

I think in order to properly support your scenario, we would need VS Code to address this issue: microsoft/vscode#227643 (comment)

[CynicatPro]

Thanks for clarifying, now that I understand it, it makes a lot more sense. Thanks for helping me with this!