Add a SCons option to control whether Godot is built as a console or GUI application on Windows

[Calinou]

Describe the project you are working on:

The Godot editor 🙂

Describe the problem or limitation you are having in your project:

When compiling Godot for Windows with the debug or release_debug target, it's compiled as a console application (even though it spawns a window on top of that). This means it's able to print to standard output/error. This also allows redirecting its output to a file.

However, when compiling Godot for Windows with the release target, it's compiled as a GUI application. This makes it impossible to see its standard output or error since no console window is visible. Even when running the executable from a command prompt, nothing will be printed. This makes it effectively impossible to redirect its output to a file.

This is a Windows limitation. Running the program in WINE may be able to overcome this limitation, but running WINE on Windows is usually impractical and requires a fair amount of setup.

Describe the feature / enhancement and how it helps to overcome the problem or limitation:

Add a windows_build_mode=console|gui SCons option that overrides the build mode regardless of the target used. (Feel free to suggest a better name for this option.)

This could help resolve godotengine/godot#24701 while making godotengine/godot#28922 significantly easier to troubleshoot.

Describe how your proposal will work, with code, pseudocode, mockups, and/or diagrams:

This can probably be done with some well-placed #ifdefs in the Windows platform code.

If this enhancement will not be used often, can it be worked around with a few lines of script?:

This needs to be decided at build-time, so no.

Is there a reason why this should be core and not an add-on in the asset library?:

This needs to be decided at build-time, so this can't be changed by an add-on.

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See also #1342.

[bruvzg]

Some things to test:

• Is it possible to redirect stdout (or stderr) from the GUI app to file/pipe with the godot > target / godot | target commands?
• Is it possible to manually attach to the parent process console (print only when it's started from console). Quick search gives something like this:

if (AttachConsole(ATTACH_PARENT_PROCESS)) {
    freopen("CONOUT$", "w", stdout);
    freopen("CONOUT$", "w", stderr);
}

[bruvzg]

Some things to test:

• Redirection works with GUI apps.
• AttachConsole also works, it's non-blocking and won't play nicely with two-panels file managers, but running app with start /wait /b godot should fix it too (and probably by adding freopen("CONIN$", "r", stdin);).

[Xrayez]

I think going for compile-time option could've been a solution too. See godotengine/godot#41307, so the scons tests=yes could automatically enable proposed windows_build_mode=console for those builds.