For a single impl candidate, try to unify it with error trait ref by compiler-errors · Pull Request #115726 · rust-lang/rust

compiler-errors · 2023-09-10T03:38:37Z

This allows us to point out an exact type mismatch when there's only one applicable impl.

compiler-errors · 2023-09-10T03:39:07Z

tests/ui/const-generics/occurs-check/unused-substs-1.stderr

   |             ^ the trait `Bar<_>` is not implemented for `A<_>`
   |
-   = help: the trait `Bar<N>` is implemented for `A<7>`
+   = help: the trait `Bar<_>` is implemented for `A<7>`


This isn't better but it's also not worse 💀

While this case isn't that much worse, there are cases where it shows something like UwU<_> is implemented for OwO<_> which no longer indicates that the type that's being printed as _ is the same in both cases. (I dislike that that sort of printing for types is ever done, but that's not specific to this PR.)

Yeah, I wonder if we could plug up the remaining infer vars here, so that those two Owo<_> and Uwu<_> are re-connected with some placeholder name.

compiler-errors · 2023-09-10T03:41:19Z

tests/ui/generic-const-items/unsatisfied-bounds.stderr

   |                  ^^ the trait `From<()>` is not implemented for `Infallible`
   |
   = help: the trait `From<!>` is implemented for `Infallible`
+   = help: ... for that trait implementation, expected `!`, found `()`


Not exactly sure what the best presentation for this is 🤔

estebank · 2023-09-27T01:43:51Z

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

+                if let [TypeError::Sorts(exp_found)] = &terrs[..] {
+                    let exp_found = self.resolve_vars_if_possible(*exp_found);
+                    err.help(format!(
+                        "... for that trait implementation, expected `{}`, found `{}`",


Suggested change

"... for that trait implementation, expected `{}`, found `{}`",

"for that trait implementation, expected `{}`, found `{}`",

compiler-errors · 2023-09-27T01:46:14Z

@rustbot author

estebank · 2023-09-27T01:46:15Z

r=me after addressing the nitpick

compiler-errors · 2023-10-02T23:46:57Z

@bors r=estebank

bors · 2023-10-02T23:46:59Z

📌 Commit 0785167 has been approved by estebank

It is now in the queue for this repository.

…iaskrgr Rollup of 6 pull requests Successful merges: - rust-lang#113053 (add notes about non-compliant FP behavior on 32bit x86 targets) - rust-lang#115726 (For a single impl candidate, try to unify it with error trait ref) - rust-lang#116158 (Don't suggest nonsense suggestions for unconstrained type vars in `note_source_of_type_mismatch_constraint`) - rust-lang#116351 (Add `must_use` on pointer equality functions) - rust-lang#116355 (Clarify float rounding direction for signed zero) - rust-lang#116361 (Bump stdarch submodule) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#115726 - compiler-errors:better-error-ref, r=estebank For a single impl candidate, try to unify it with error trait ref This allows us to point out an exact type mismatch when there's only one applicable impl. cc `@asquared31415` r? `@estebank`

rustbot assigned estebank Sep 10, 2023

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 Sep 10, 2023

compiler-errors commented Sep 10, 2023

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estebank reviewed Sep 27, 2023

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 27, 2023

compiler-errors added 2 commits October 2, 2023 23:14

For a single impl candidate, try to unify it with error trait ref

8be12f4

Point out the actual mismatch error

0785167

rust-cloud-vms bot force-pushed the better-error-ref branch from 3c81efe to 0785167 Compare October 2, 2023 23:14

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 2, 2023

matthiaskrgr mentioned this pull request Oct 3, 2023

Rollup of 6 pull requests #116372

Merged

bors merged commit ff3b15e into rust-lang:master Oct 3, 2023

rustbot added this to the 1.75.0 milestone Oct 3, 2023

pvdrz mentioned this pull request Oct 4, 2023

Fix divergence from upstream master ferrocene/ferrocene#23

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For a single impl candidate, try to unify it with error trait ref#115726

For a single impl candidate, try to unify it with error trait ref#115726
bors merged 2 commits intorust-lang:masterfrom
compiler-errors:better-error-ref

compiler-errors commented Sep 10, 2023

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