Do not eagerly reject inference vars when trying to resolve method calls. #126316

oli-obk · 2024-06-12T10:11:05Z

Reintroduces the changes reverted in #126258 and fixes the regression in the old solver.

The new solver will still fail on

pub trait Parser<E> {
    fn parse(&self) -> E;
}

impl<E, T: Fn() -> E> Parser<E> for T {
    fn parse(&self) -> E {
        self()
    }
}

pub fn recursive_fn<E>() -> impl Parser<E> {
    move || recursive_fn().parse()
    //[next]~^ ERROR: type annotations needed
}

because while type checking the method call .parse(), when looking for candidates, we end up not finding any, as the only information we have is that there's an unresolved AliasTy(opaque, infer_var) floating around while looking for a method call on infer_var.

This obviously seems fixable by looking at said obligation, but I'd prefer to tackle that separately (I got half an impl locally, but there are multiple paths forward that we should discuss)

r? @lcnr @compiler-errors

I'm going to split out the effect-free cleanups and the inference changes to separate PRs, so we can review them in isolation, but with the goal of enabling this PR to land

…r-errors Avoid a bunch of booleans in favor of Result<(), ErrorGuaranteed> as that more robustly proves that an error has been emitted pulled out of rust-lang#126316 This PR cannot have any effect on compilation. All it does is shift a `Ty::new_misc_error` to a `span_delayed_bug` and preserve the `ErrorGuaranteed` in all other cases

Rollup merge of rust-lang#126317 - oli-obk:recursive_rpit4, r=compiler-errors Avoid a bunch of booleans in favor of Result<(), ErrorGuaranteed> as that more robustly proves that an error has been emitted pulled out of rust-lang#126316 This PR cannot have any effect on compilation. All it does is shift a `Ty::new_misc_error` to a `span_delayed_bug` and preserve the `ErrorGuaranteed` in all other cases

bors · 2024-06-12T23:59:43Z

☔ The latest upstream changes (presumably #126345) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2024-06-13T08:08:52Z

☔ The latest upstream changes (presumably #126374) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2024-06-14T10:16:56Z

☔ The latest upstream changes (presumably #126462) made this pull request unmergeable. Please resolve the merge conflicts.

oli-obk · 2024-06-14T10:19:41Z

@rustbot ready the component PRs have landed

lcnr

want to take some time to look at when exactly we don't error if there's an auto-deref step resulting in an infer var, will get to this next week hopefully

bors · 2024-06-16T10:48:16Z

☔ The latest upstream changes (presumably #126540) made this pull request unmergeable. Please resolve the merge conflicts.

…en types of opaque types."" This reverts commit ad00868.

…d call checks

…ution handle it

bors · 2024-09-06T16:04:36Z

☔ The latest upstream changes (presumably #121848) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot assigned lcnr Jun 12, 2024

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 12, 2024

oli-obk mentioned this pull request Jun 12, 2024

Avoid a bunch of booleans in favor of Result<(), ErrorGuaranteed> as that more robustly proves that an error has been emitted #126317

Merged