bootstrap: make --exclude consistent with --skip in libtest

[jyn514]

Right now, there are two ways to ignore tests:

1. Pass x test --exclude tests/ui/weird-exprs.rs to bootstrap
2. Pass x test --test-args --skip=tests/ui/weird-exprs.rs to compiletest

It's weird that these use different arguments. --skip is public-facing, so we should rename --exclude to --skip in bootstrap.

I don't have a strong opinion on whether to keep --exclude around as an alias for --skip, but --skip should be the one we document.

Note that --exclude is slightly different from --skip because it can also applies to whole Steps, not just tests, and doesn't support substring matching. But I don't think it's different enough to be worth having a different name.

[Mark-Simulacrum]

It's worth noting that they also have pretty different semantics. Skipping a test is reliable (we wouldn't ever run it) where exclude in bootstrap only applies to the defaults for that command, something ensure'ing that step will still run it. (keep-stage has closer semantics to skip, in some sense).

I'm not sure if it makes sense to rename here, the different names don't feel like they cause confusion to me?

[jyn514]

Hmm that's fair - I'm more worried about discoverability than confusion, but I do see how the new name could be confusing.

For context, I thought of this after someone looked for --skip in bootstrap's help output and didn't find it: https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/UI.20test.20fails.20with.20clang.20as.20a.20linker

[meysam81]

Hey guys,
I'm a first-time contributor, enthusiast, and admirer of the Rust lang.
Is there anything I can do here?
Regards.

[albertlarsan68]

Hello @meysam81,

The bare minimum would be to change this line: https://github.com/rust-lang/rust/blob/master/src/bootstrap/flags.rs#L71
You can either just rename this flag, or duplicate it to keep the current command lines compatible.
Then, as the end goal is to change the option, rename the struct member there:
https://github.com/rust-lang/rust/blob/master/src/bootstrap/config.rs#L133
Following the compiler errors, you should end at this point:
https://github.com/rust-lang/rust/blob/master/src/bootstrap/config.rs#L1116
There, if you decided to rename the command-line flag, you should rename both sides of this line, else you should change the left side of this assignment, and duplicate the line to also change the right side to the new flag name.
What is left to do is to fix the remaining compiler errors, then you have a PR ready to be reviewed!

[meysam81]

@rustbot claim