Suggest associated type bounds on problematic associated equality bounds #122120

fmease · 2024-03-07T00:20:16Z

Fixes #105056. TL;DR: Suggest Trait<Ty: Bound> on Trait<Ty = Bound> in Rust >=2021.

~~Blocked on #122055 (stabilization of associated_type_bounds), I'd say.~~ (merged)

fmease · 2024-03-07T00:31:21Z

compiler/rustc_hir_analysis/src/astconv/lint.rs

+    ///
+    /// *Bare* trait object types are ones that aren't preceeded by the keyword `dyn`.
+    /// In edition 2021 and onward we emit a hard error for them.
+    pub(super) fn prohibit_or_lint_bare_trait_object_ty(


(esthetics) moves the only non-priv item to the top; all the other items are helpers of this one

new name is clearer: bare trait? bare trait object (ty); furthermore this isn't “maybe linting” but it's first & foremost prohibiting (if we assume the latest stable edition to be the canonical edition) otherwise linting — in older editions.

fmease · 2024-03-07T00:37:39Z

compiler/rustc_hir/src/hir.rs

 ///
-/// FIXME(alexreg): why have a separate type for the binding case,


I never understood this FIXME whenever I came across these docs: The FIXME was created in the same commit as the one that introduced TypeBindingKind in favor of the now gone struct field ty: P<Ty> the FIXME mentions...

fmease · 2024-03-07T00:41:51Z

compiler/rustc_parse/messages.ftl

@@ -14,10 +14,6 @@ parse_array_index_offset_of = array indexing not supported in offset_of

 parse_assignment_else_not_allowed = <assignment> ... else {"{"} ... {"}"} is not allowed

-parse_assoc_lifetime = associated lifetimes are not supported


This message was confusing imo, it talked about a “fictive” Rust feature, associated lifetimes as if that term was common knowledge. If at all, I would've expected this message to trigger on X<'a = 'static> ('a is the “associated lifetime”, 'static is the “projected lifetime”), not on X<T = 'static> as it currently does on master.

compiler-errors · 2024-03-07T00:58:42Z

:^) thanks

compiler/rustc_hir/src/hir.rs

compiler/rustc_hir_analysis/src/astconv/lint.rs

fmease · 2024-03-07T10:19:31Z

tests/ui/associated-type-bounds/suggest-assoc-ty-bound-on-eq-bound.stderr

We could think about suppressing some of the other trait object type diagnostics.

fmease · 2024-03-22T23:31:29Z

Okay, I've dialed it down. Didn't make anything translatable because if I started doing that I'd find myself in a rabbit hole of updating the neighboring code, too, since it's all interconnected in this case. I also dropped some other changes. I plan on submitting a diagnostic migration PR for rustc_hir_analysis soon anyway.

r? compiler-errors or compiler, no rush tho

compiler-errors · 2024-03-26T18:03:13Z

@bors r+

bors · 2024-03-26T18:03:15Z

📌 Commit 3879acb has been approved by compiler-errors

It is now in the queue for this repository.

…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#108675 (Document `adt_const_params` feature in Unstable Book) - rust-lang#122120 (Suggest associated type bounds on problematic associated equality bounds) - rust-lang#122589 (Fix diagnostics for async block cloning) - rust-lang#122835 (Require `DerefMut` and `DerefPure` on `deref!()` patterns when appropriate) - rust-lang#123049 (In `ConstructCoroutineInClosureShim`, pass receiver by mut ref, not mut pointer) - rust-lang#123055 (enable cargo miri test doctests) - rust-lang#123057 (unix fs: Make hurd using explicit new rather than From) - rust-lang#123087 (Change `f16` and `f128` clippy stubs to be nonpanicking) - rust-lang#123103 (Rename `Inherited` -> `TypeckRootCtxt`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#122120 - fmease:sugg-assoc-ty-bound-on-eq-bound, r=compiler-errors Suggest associated type bounds on problematic associated equality bounds Fixes rust-lang#105056. TL;DR: Suggest `Trait<Ty: Bound>` on `Trait<Ty = Bound>` in Rust >=2021. ~~Blocked on rust-lang#122055 (stabilization of `associated_type_bounds`), I'd say.~~ (merged)

jdahlstrom · 2024-03-27T10:39:11Z

Thanks!

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 Mar 7, 2024

fmease added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 7, 2024

fmease commented Mar 7, 2024

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fmease added 4 commits March 22, 2024 23:05

Small tweaks to the linting code for bare trait object types

6b85f07

Update docs of hir::TypeBinding

d3d77a8

Suggest assoc ty bound on bare dyn trait in eq constraint

22b9e96

Suggest assoc ty bound on lifetime in eq constraint

3879acb

fmease force-pushed the sugg-assoc-ty-bound-on-eq-bound branch from fd3a91f to 3879acb Compare March 22, 2024 23:27

rustbot assigned compiler-errors Mar 22, 2024

compiler-errors approved these changes Mar 26, 2024

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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-review Status: Awaiting review from the assignee but also interested parties. labels Mar 26, 2024

matthiaskrgr mentioned this pull request Mar 26, 2024

Rollup of 9 pull requests #123108

Merged

bors merged commit ff8cdc9 into rust-lang:master Mar 27, 2024
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rustbot added this to the 1.79.0 milestone Mar 27, 2024

fmease deleted the sugg-assoc-ty-bound-on-eq-bound branch March 27, 2024 10:03

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Suggest associated type bounds on problematic associated equality bounds #122120

Suggest associated type bounds on problematic associated equality bounds #122120

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jdahlstrom commented Mar 27, 2024

		///
		/// FIXME(alexreg): why have a separate type for the binding case,

		@@ -14,10 +14,6 @@ parse_array_index_offset_of = array indexing not supported in offset_of

		parse_assignment_else_not_allowed = <assignment> ... else {"{"} ... {"}"} is not allowed

		parse_assoc_lifetime = associated lifetimes are not supported

Suggest associated type bounds on problematic associated equality bounds #122120

Suggest associated type bounds on problematic associated equality bounds #122120

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