SceneTree.quit() ignores given exit code with --script

[razcore-rad]

Tested versions

• Reproducible in: 4.2.1.stable.official.b09f793f5, 4.2.2.rc1.official.c7fb0645a

System information

Ubuntu 23.10, Vulkan, NVIDIA GeForce RTX™ 2060 / NVIDIA GeForce RTX™ 2060

Issue description

The following code:

extends SceneTree


func _init() -> void:
	quit(1)

saved as dev.gd, when ran with godot --headless --script dev.gd always returns with a 0 exit code:

❯ godot --headless --script dev.gd | complete
╭───────────┬──────────────────────────────────────────────────────────────────────╮
│ stdout    │ Godot Engine v4.2.2.rc1.official.c7fb0645a - https://godotengine.org │
│           │                                                                      │
│           │                                                                      │
│ exit_code │ 0                                                                    │
╰───────────┴──────────────────────────────────────────────────────────────────────╯

Steps to reproduce

Check issue description.

Minimal reproduction project (MRP)

not applicable

[akien-mga]

I can reproduce it with --script, but not when running an actual project.

[LeoBelda]

I can't reproduce it on Windows.
It seems to be caused by a call to OS::set_exit_code in the Linux main:

godot/platform/linuxbsd/godot_linuxbsd.cpp

Lines 84 to 87 in 5f05e2b

	if (Main::start()) {
	os.set_exit_code(EXIT_SUCCESS);
	os.run(); // it is actually the OS that decides how to run
	}

Copying this line into Windows widechar_main allowed me to reproduce the issue: the exit code set by the script during the execution of Main::start gets overridden.

[akien-mga]

Fixed by #89229.