Technically a soundness bug: test_main_static_abort clears the environment

[Manishearth]

rust/library/test/src/lib.rs

Lines 206 to 212 in 7dc2c16

	pub fn test_main_static_abort(tests: &[&TestDescAndFn]) {
	// If we're being run in SpawnedSecondary mode, run the test here. run_test
	// will then exit the process.
	if let Ok(name) = env::var(SECONDARY_TEST_INVOKER_VAR) {
	unsafe {
	env::remove_var(SECONDARY_TEST_INVOKER_VAR);
	}

https://doc.rust-lang.org/stable/std/env/fn.remove_var.html

AIUI since libtest is multithreaded, this is not a safe invocation of remove_var from the public safe test_main_static_abort function.

In practice, this doesn't matter: Rust libraries aren't manually calling this function, and if you can cause UB in a custom test harness I don't think it's that big a deal.

Filing for completeness' sake. It would probably make sense to at least document why this is okay here.

(This issue was found during an agentic safety audit using Gemini)

[workingjubilee]

@Manishearth std manages its own accesses to sync them, so the actual assumption is that you aren't using a random dynamic library or something that also manipulates the environment.

[workingjubilee]

"please use Rust code for your Rust test harness and don't randomly bodge it together with five other languages? thanks."

[Manishearth]

Yeah, basically.

This isn't a real issue but also I don't like leaving holes like this undocumented.