Implement suggestion for never type fallback lints #132383

compiler-errors · 2024-10-31T04:36:53Z

Just opening this up for vibes; it's not done yet. I'd still like to make this suggestable in a few more cases before merge:

Try to annotate _ -> ()
Try to annotate local variables if they're un-annotated: let x = ... -> let x: () = ...
Try to annotate the self type of a Trait::method() -> <() as Trait>::method().

The only other case we may want to suggest is a missing turbofish, like f() -> f::<()>(). That may be possible, but seems overly annoying.

This partly addresses #132358; the other half of fixing that would be to make the error message a bit better, perhaps just special casing the ? operator 🤔 I don't think I'll do that part.

tests/ui/never_type/dependency-on-fallback-to-unit.stderr

compiler-errors · 2024-10-31T17:01:22Z

yippee this is ready i think

compiler-errors · 2024-10-31T17:38:37Z

We could, perhaps, even reuse this suggestion to tell users to annotate their code with () even after edition 2024.

WaffleLapkin

I love the diagnostic changes, that all look very good!

I have a couple minor questions.

WaffleLapkin · 2024-10-31T22:21:44Z

compiler/rustc_hir_typeck/src/fallback.rs

+            // We can't turbofish consts :(
+            && args.iter().all(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_) | ty::GenericArgKind::Lifetime(_)))


I'm not sure I understand? this checks that there are no const genetics, but you can turbofish those?

I wanted to limit the complexity of the suggestion so it would just either have _ for all the non fallback args, but consts cant use _

WaffleLapkin · 2024-10-31T22:25:31Z

compiler/rustc_hir_typeck/src/fallback.rs

+}
+
+/// Try to collect a useful suggestion to preserve fallback to `()`.
+struct VidVisitor<'a, 'tcx> {


maybe name it daunting else? I'm not sure what tho, but something that highlights that it finds possible suggestion places...

Ya i can name it better and give it a pass for more comments

r=me after that then

tests/ui/never_type/dependency-on-fallback-to-unit.stderr

compiler-errors · 2024-11-01T01:49:08Z

@bors r=WaffleLapkin

bors · 2024-11-01T01:49:11Z

📌 Commit b4248ae has been approved by WaffleLapkin

It is now in the queue for this repository.

…k-sugg, r=WaffleLapkin Implement suggestion for never type fallback lints r? `@WaffleLapkin` Just opening this up for vibes; it's not done yet. I'd still like to make this suggestable in a few more cases before merge: - [x] Try to annotate `_` -> `()` - [x] Try to annotate local variables if they're un-annotated: `let x = ...` -> `let x: () = ...` - [x] Try to annotate the self type of a `Trait::method()` -> `<() as Trait>::method()`. The only other case we may want to suggest is a missing turbofish, like `f()` -> `f::<()>()`. That may be possible, but seems overly annoying. This partly addresses rust-lang#132358; the other half of fixing that would be to make the error message a bit better, perhaps just special casing the `?` operator 🤔 I don't think I'll do that part.

…iaskrgr Rollup of 6 pull requests Successful merges: - rust-lang#131829 (Remove support for `-Zprofile` (gcov-style coverage instrumentation)) - rust-lang#132341 (Reject raw lifetime followed by `'`, like regular lifetimes do) - rust-lang#132369 (style-guide: Only use the new binop heuristic for assignments) - rust-lang#132383 (Implement suggestion for never type fallback lints) - rust-lang#132437 (coverage: Regression test for inlining into an uninstrumented crate) - rust-lang#132438 (Remove unncessary option for default rust-analyzer setting) r? `@ghost` `@rustbot` modify labels: rollup

…k-sugg, r=WaffleLapkin Implement suggestion for never type fallback lints r? ``@WaffleLapkin`` Just opening this up for vibes; it's not done yet. I'd still like to make this suggestable in a few more cases before merge: - [x] Try to annotate `_` -> `()` - [x] Try to annotate local variables if they're un-annotated: `let x = ...` -> `let x: () = ...` - [x] Try to annotate the self type of a `Trait::method()` -> `<() as Trait>::method()`. The only other case we may want to suggest is a missing turbofish, like `f()` -> `f::<()>()`. That may be possible, but seems overly annoying. This partly addresses rust-lang#132358; the other half of fixing that would be to make the error message a bit better, perhaps just special casing the `?` operator 🤔 I don't think I'll do that part.

Rollup of 13 pull requests Successful merges: - rust-lang#131829 (Remove support for `-Zprofile` (gcov-style coverage instrumentation)) - rust-lang#132369 (style-guide: Only use the new binop heuristic for assignments) - rust-lang#132383 (Implement suggestion for never type fallback lints) - rust-lang#132437 (coverage: Regression test for inlining into an uninstrumented crate) - rust-lang#132438 (Remove unncessary option for default rust-analyzer setting) - rust-lang#132439 (Add `f16` and `f128` to `invalid_nan_comparison`) - rust-lang#132445 (Cleanup attributes around unchecked shifts and unchecked negation in const) - rust-lang#132448 (Add missing backtick) - rust-lang#132450 (Show actual MIR when MIR building forgot to terminate block) - rust-lang#132451 (remove some unnecessary rustc_allow_const_fn_unstable) - rust-lang#132455 (make const_alloc_layout feature gate only about functions that are already stable) - rust-lang#132456 (Move remaining inline assembly test files into asm directory) - rust-lang#132459 (feat(byte_sub_ptr): unstably add ptr::byte_sub_ptr) r? `@ghost` `@rustbot` modify labels: rollup

…llaumeGomez Rollup of 14 pull requests Successful merges: - rust-lang#131829 (Remove support for `-Zprofile` (gcov-style coverage instrumentation)) - rust-lang#132369 (style-guide: Only use the new binop heuristic for assignments) - rust-lang#132383 (Implement suggestion for never type fallback lints) - rust-lang#132413 (update offset_of! docs to reflect the stabilization of nesting) - rust-lang#132438 (Remove unncessary option for default rust-analyzer setting) - rust-lang#132439 (Add `f16` and `f128` to `invalid_nan_comparison`) - rust-lang#132444 (rustdoc: Directly use rustc_abi instead of reexports) - rust-lang#132445 (Cleanup attributes around unchecked shifts and unchecked negation in const) - rust-lang#132448 (Add missing backtick) - rust-lang#132450 (Show actual MIR when MIR building forgot to terminate block) - rust-lang#132451 (remove some unnecessary rustc_allow_const_fn_unstable) - rust-lang#132455 (make const_alloc_layout feature gate only about functions that are already stable) - rust-lang#132456 (Move remaining inline assembly test files into asm directory) - rust-lang#132459 (feat(byte_sub_ptr): unstably add ptr::byte_sub_ptr) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#132383 - compiler-errors:never-type-fallback-sugg, r=WaffleLapkin Implement suggestion for never type fallback lints r? ```@WaffleLapkin``` Just opening this up for vibes; it's not done yet. I'd still like to make this suggestable in a few more cases before merge: - [x] Try to annotate `_` -> `()` - [x] Try to annotate local variables if they're un-annotated: `let x = ...` -> `let x: () = ...` - [x] Try to annotate the self type of a `Trait::method()` -> `<() as Trait>::method()`. The only other case we may want to suggest is a missing turbofish, like `f()` -> `f::<()>()`. That may be possible, but seems overly annoying. This partly addresses rust-lang#132358; the other half of fixing that would be to make the error message a bit better, perhaps just special casing the `?` operator 🤔 I don't think I'll do that part.

rustbot assigned WaffleLapkin Oct 31, 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 Oct 31, 2024

compiler-errors commented Oct 31, 2024

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tests/ui/never_type/dependency-on-fallback-to-unit.stderr Show resolved Hide resolved

compiler-errors force-pushed the never-type-fallback-sugg branch from ccb4fde to b4a6549 Compare October 31, 2024 16:58

WaffleLapkin reviewed Oct 31, 2024

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compiler-errors added 6 commits November 1, 2024 01:46

nit: stop using TypeckRootCtxt

588c7a9

Suggest annotations for never type fallback

41966e7

Suggest adding self type to method

ea4fb7c

And locals too

c930bba

And also suggest for qpaths

df6f584

nits

b4248ae

compiler-errors force-pushed the never-type-fallback-sugg branch from b4a6549 to b4248ae Compare November 1, 2024 01:46

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 Nov 1, 2024

matthiaskrgr mentioned this pull request Nov 1, 2024

Rollup of 6 pull requests #132446

Closed

jieyouxu mentioned this pull request Nov 1, 2024

Rollup of 13 pull requests #132462

Closed

GuillaumeGomez mentioned this pull request Nov 1, 2024

Rollup of 14 pull requests #132470

Merged

bors merged commit e31a5ca into rust-lang:master Nov 2, 2024
6 checks passed

rustbot added this to the 1.84.0 milestone Nov 2, 2024

matthiaskrgr mentioned this pull request Nov 2, 2024

ICE: node_type: no type for node HirId #132517

Closed

compiler-errors mentioned this pull request Nov 12, 2024

2024 dependency_on_unit_never_type_fallback doesn't display during 2024 edition migration #132930

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Implement suggestion for never type fallback lints #132383

Implement suggestion for never type fallback lints #132383

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bors commented Nov 1, 2024

		// We can't turbofish consts :(
		&& args.iter().all(\|arg\| matches!(arg.unpack(), ty::GenericArgKind::Type(_) \| ty::GenericArgKind::Lifetime(_)))

Implement suggestion for never type fallback lints #132383

Implement suggestion for never type fallback lints #132383

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