SCons: Fix compilation database generation with MSVC

[akien-mga]

Fixes #54434.

Co-authored-by: @dmoody256

Didn't get to test it myself, would be great if a few MSVC users could confirm it works (to enable compilation database generation, you should pass compiledb=yes to SCons).

[akien-mga]

The platform/windows/detect.py seems to break MSVC detection on CI it seems, it falls back partially to MinGW (but keeping MSVC parameters) and fails:

scons: Building targets ...
run(["core\object\gdvirtual.gen.inc"], ["core\object\make_virtuals.py"])
Executing builder function in subprocess: module_path='D:\\a\\godot\\godot\\core\\object\\make_virtuals.py', parameter_file='C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\7f6697c8b1d243b8b26da514830bd521.json', parameter_file_size=17774, target=['D:\\a\\godot\\godot\\core\\object\\gdvirtual.gen.inc'], source=['D:\\a\\godot\\godot\\core\\object\\make_virtuals.py']
build_rd_headers(["servers\rendering\renderer_rd\shaders\blit.glsl.gen.h"], ["servers\rendering\renderer_rd\shaders\blit.glsl"])
Executing builder function in subprocess: module_path='D:\\a\\godot\\godot\\glsl_builders.py', parameter_file='C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\302887ed57094ab2979a18b070002895.json', parameter_file_size=17834, target=['D:\\a\\godot\\godot\\servers\\rendering\\renderer_rd\\shaders\\blit.glsl.gen.h'], source=['D:\\a\\godot\\godot\\servers\\rendering\\renderer_rd\\shaders\\blit.glsl']
x86_64-w64-mingw32-g++ /Foplatform\windows\godot_windows.windows.opt.tools.x86_64.obj /c platform\windows\godot_windows.cpp -std=gnu++17 /TP -Wno-error=cpp /nologo -O2 -O2 -mwindows -Wall -Wshadow-local -Wno-misleading-indentation -Werror /DDEBUG_ENABLED /DNO_EDITOR_SPLASH /DWINDOWS_ENABLED /DWASAPI_ENABLED /DWINMIDI_ENABLED /DWINVER=0x0601 /D_WIN32_WINNT=0x0601 /DVULKAN_ENABLED /DGLES3_ENABLED /DMINGW_ENABLED /DMINGW_HAS_SECURE_API=1 /DTOOLS_ENABLED /DMINIZIP_ENABLED /DZSTD_STATIC_LINKING_ONLY /DUSE_VOLK /DVK_USE_PLATFORM_WIN32_KHR /DGLAD_ENABLED /DGLES_OVER_GL /Ithirdparty\freetype\include /Ithirdparty\libpng /Ithirdparty\glad /Ithirdparty\volk /Ithirdparty\vulkan /Ithirdparty\vulkan\include /Ithirdparty\zstd /Ithirdparty\zlib /Iplatform\windows /I.
x86_64-w64-mingw32-g++ /Foplatform\windows\crash_handler_windows.windows.opt.tools.x86_64.obj /c platform\windows\crash_handler_windows.cpp -std=gnu++17 /TP -Wno-error=cpp /nologo -O2 -O2 -mwindows -Wall -Wshadow-local -Wno-misleading-indentation -Werror /DDEBUG_ENABLED /DNO_EDITOR_SPLASH /DWINDOWS_ENABLED /DWASAPI_ENABLED /DWINMIDI_ENABLED /DWINVER=0x0601 /D_WIN32_WINNT=0x0601 /DVULKAN_ENABLED /DGLES3_ENABLED /DMINGW_ENABLED /DMINGW_HAS_SECURE_API=1 /DTOOLS_ENABLED /DMINIZIP_ENABLED /DZSTD_STATIC_LINKING_ONLY /DUSE_VOLK /DVK_USE_PLATFORM_WIN32_KHR /DGLAD_ENABLED /DGLES_OVER_GL /Ithirdparty\freetype\include /Ithirdparty\libpng /Ithirdparty\glad /Ithirdparty\volk /Ithirdparty\vulkan /Ithirdparty\vulkan\include /Ithirdparty\zstd /Ithirdparty\zlib /Iplatform\windows /I.
=====
platform\windows\godot_windows.cpp:31:10: fatal error: main/main.h: No such file or directory
   31 | #include "main/main.h"
      |          ^~~~~~~~~~~~~
scons: *** [platform\windows\godot_windows.windows.opt.tools.x86_64.obj] Error 1
compilation terminated.

=====
=====
platform\windows\crash_handler_windows.cpp:33:10: fatal error: core/config/project_settings.h: No such file or directory
   33 | #include "core/config/project_settings.h"
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
scons: *** [platform\windows\crash_handler_windows.windows.opt.tools.x86_64.obj] Error 1

=====
scons: building terminated because of errors.

[dmoody256]

The platform/windows/detect.py change may have been specific to the issue I was having when my visual studio was installed incorrectly. At first I did not supply that argument, but still always mingw was selected. I started supplying the msvc_version=14.2 to force it, which it then still was selecting mingw. So when I made that change to detect.py then it forced msvc selection and I saw my msvc install was corrupt and then I fixed the msvc install.

That change in platform/windows/detect.py should be reverted. SCons will set the MSVC_VERSION internally if your MSVC install is valid (My case it wasn't so it wasn't setting MSVC_VERSION internally). Although if msvc_version is set but MSVC_VERSION is not set, may be useful to raise an error. In this case the user explicitly wants MSVC but it is not a possible configuration, so diverting them to mingw is confusing.

[derammo]

I used the patch of this PR against master, using SCons: v4.3.0.559790274f66fa55251f5754de34820a29c7327a and it was successful in creating the compile_commands.json. I was running in x64 Native Tools Command Prompt for VS 2019 so the detect logic was using the easy path (everything already set up correctly.)

It is still not useful for my work, because I need the full build info (link commands etc.) but it does seem to fix the compile_commands.json :). Blatant plug for please reconsidering #63724

[bruvzg]

I can't test it right now, but moving it after toolchain setup seems like a right way to go.

[akien-mga]

Cherry-picked for 3.6.

[akien-mga]

Cherry-picked for 3.5.1.