./x.py test --host='' does nothing and succeeds

[jonas-schievink]

Running ./x.py test --host='' builds bootstrap, but then exits successfully without building Rust and running any test. This should probably cause an error instead.

cc @Mark-Simulacrum

[jyn514]

Here's the relevant code:

rust/src/bootstrap/builder.rs

Lines 292 to 298 in e9e0908

	// Determine the targets participating in this rule.
	let targets = if self.only_hosts { &builder.hosts } else { &builder.targets };
	for target in targets {
	let run = RunConfig { builder, paths: pathsets.clone(), target: *target };
	(self.make_run)(run);
	}

We should probably have an assert!(!targets.is_empty()) there or something (not an assert because of #107019, but something like it).

[madsravn]

@rustbot claim

[madsravn]

@rustbot release-assignment

[AleksaBajat]

Hey @Mark-Simulacrum,
Is this issue still something that needs to be worked on? I noticed in the previous PR discussion that this might not require a change. However, if we still want to address this issue, I can review flags.rs and other mentioned code and attempt to make a more appropriate fix.

[Mark-Simulacrum]

I'm going to go ahead and close this. I don't think it's critical that every invocation that is mostly a no-op errors. If you request an empty set, getting an empty set seems fine.