Suggests turbofish in patterns #114300

mu001999 · 2023-07-31T18:04:04Z

Fixes #114112

r? @estebank

compiler/rustc_parse/src/parser/path.rs

compiler/rustc_parse/src/parser/pat.rs

tests/ui/did_you_mean/issue-114112.stderr

mu001999 · 2023-08-01T08:09:02Z

r? @compiler-errors

compiler/rustc_parse/src/parser/path.rs

tests/ui/suggestions/issue-64252-self-type.stderr

estebank

If we can manage to keep the suggestion for wrong arbitrary self types that I highlighted, the current approach should work.

mu001999 · 2023-08-02T16:02:57Z

@estebank The new commit keeps the suggestions for wrong arbitrary self types that you highlighted. Please review again, thanks! ;)

rustbot · 2023-08-02T16:14:04Z

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

compiler/rustc_parse/src/parser/pat.rs

estebank · 2023-08-02T17:05:45Z

tests/ui/anon-params/anon-params-denied-2018.stderr

+help: if this is a `self` type, give it a parameter name
+ |
+LL | fn foo_with_qualified_path(self: <Bar as T>::Baz);
+ | 


Mmm... Arbitrary self types only support a handful of pointer types (Box, Arc, Rc). General arbitrary self types are unlikely to be supported any time soon, so adding this suggestion would be confusing to users. (I know, I know, but we have to try to minimize confusion to users, the only thing worse than an error without a suggestion is an error with a wrong suggestion.)

As mentioned below (#114300 (comment))

estebank · 2023-08-02T17:07:02Z

tests/ui/parser/issues/issue-22647.rs

@@ -1,5 1,5 @@
 fn main() {
- let caller<F> = |f: F| //~ ERROR expected one of `:`, `;`, `=`, `@`, or `|`, found `<`
+ let caller<F> = |f: F| //~ ERROR generic args in patterns require the turbofish syntax


Looking at this error, the suggestion we should be giving is to add a type, but don't know how hard it would be to change.

Like function parameters, maybe we can also suggest name: caller<F> or _: caller<F>? I think it may be more general, because caller<F> is more like a type.

Yeah, I think the later is the better suggestion (particularly if the rest can be parsed as a type until ; or = is reached).

estebank · 2023-08-02T17:08:14Z

tests/ui/span/issue-34264.stderr

 --> $DIR/issue-34264.rs:1:14
 |
 LL | fn foo(Option<i32>, String) {}
- | ^ expected one of `:`, `@`, or `|`
+ | ^ expected one of 9 possible tokens
 |
 = note: anonymous parameters are removed in the 2018 edition (see RFC 1685)
 help: if this is a `self` type, give it a parameter name


Oh, I see that we already provide a bad arbitrary self type suggestion :-/

Yes, and I think we can't emit suggestions only for pointer types in the parsing stage, since we can use type alias type P<T> = Box<T>. So I think this is acceptable and the current behaviour extends the old arbitrary self type suggestions.

estebank · 2023-08-02T17:11:47Z

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -1579,7 1579,7 @@ impl<'a> Parser<'a> {
 self.expect(&token::ModSep)?;

 let mut path = ast::Path { segments: ThinVec::new(), span: DUMMY_SP, tokens: None };
- self.parse_path_segments(&mut path.segments, T::PATH_STYLE, None)?;
+ self.parse_path_segments(&mut path.segments, T::PATH_STYLE, None, None)?;


I'm not super happy with the proliferation of Nones this causes, but I also don't have much of a better proposal (short of having a *_with_pat_location family of methods).

The new changes reduce the Nones, but there are still some (seemingly unavoidable at the moment)

estebank · 2023-08-02T17:13:14Z

tests/ui/span/issue-34264.stderr

@@ -1,8 1,8 @@
-error: expected one of `:`, `@`, or `|`, found `<`
+error: expected one of `!`, `(`, `...`, `..=`, `..`, `::`, `:`, `{`, or `|`, found `<`


If we can, I'd like to revert whatever causes this message change, as I feel the previous one did a good job leading people towards the problem of a missing :

This is reverted now! ;)

estebank · 2023-08-03T12:47:57Z

@bors r

bors · 2023-08-03T12:47:59Z

📌 Commit dce7e87 has been approved by estebank

It is now in the queue for this repository.

…bank Suggests turbofish in patterns Fixes rust-lang#114112 r? `@estebank`

…bank Suggests turbofish in patterns Fixes rust-lang#114112 r? ``@estebank``

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#113657 (Expand, rename and improve `incorrect_fn_null_checks` lint) - rust-lang#114237 (parser: more friendly hints for handling `async move` in the 2015 edition) - rust-lang#114300 (Suggests turbofish in patterns) - rust-lang#114372 (const validation: point at where we found a pointer but expected an integer) - rust-lang#114395 ([rustc_span][perf] Hoist lookup sorted by words out of the loop.) - rust-lang#114403 (fix the span in the suggestion of remove question mark) - rust-lang#114408 (Temporary remove myself from review rotation) - rust-lang#114415 (Skip checking of `rustc_codegen_gcc` with vendoring enabled) r? `@ghost` `@rustbot` modify labels: rollup

…bank Suggests turbofish in patterns Fixes rust-lang#114112 r? ```@estebank```

rustbot assigned estebank Jul 31, 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 Jul 31, 2023

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mu001999 force-pushed the fix/turbofish-pat branch 2 times, most recently from b60f7bb to 7146f92 Compare August 1, 2023 08:08

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Suggests turbofish in patterns

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Keep the suggestion for wrong arbitrary self types

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Fix rustfmt dep

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mu001999 added 3 commits August 3, 2023 05:18

Apply suggestions

41e85c3

Avoid too many expected symbols and reduce Nones

8c8af6c

Reduce arbitrary self type suggestions

dce7e87

mu001999 force-pushed the fix/turbofish-pat branch from 25264ee to dce7e87 Compare August 3, 2023 10:35

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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 Aug 3, 2023

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Aug 3, 2023

Rollup merge of rust-lang#114300 - MU001999:fix/turbofish-pat, r=este…

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…bank Suggests turbofish in patterns Fixes rust-lang#114112 r? `@estebank`

matthiaskrgr mentioned this pull request Aug 3, 2023

Rollup of 7 pull requests #114419

Closed

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Aug 3, 2023

Rollup merge of rust-lang#114300 - MU001999:fix/turbofish-pat, r=este…

17e9111

…bank Suggests turbofish in patterns Fixes rust-lang#114112 r? ``@estebank``

This was referenced Aug 3, 2023

Rollup of 8 pull requests #114421

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Rollup of 8 pull requests #114424

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bors merged commit 51d1dac into rust-lang:master Aug 3, 2023
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rustbot added this to the 1.73.0 milestone Aug 3, 2023

mu001999 deleted the fix/turbofish-pat branch August 4, 2023 02:27

This was referenced Sep 12, 2023

regression: generic args in patterns require the turbofish syntax #115780

Closed

Only suggest turbofish in patterns if we may recover #115785

Merged

calebcartwright pushed a commit to calebcartwright/rust that referenced this pull request Oct 23, 2023

Rollup merge of rust-lang#114300 - MU001999:fix/turbofish-pat, r=este…

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…bank Suggests turbofish in patterns Fixes rust-lang#114112 r? ```@estebank```

calebcartwright pushed a commit to calebcartwright/rust that referenced this pull request Jun 22, 2024

Rollup merge of rust-lang#114300 - MU001999:fix/turbofish-pat, r=este…

4cc22af

…bank Suggests turbofish in patterns Fixes rust-lang#114112 r? ```@estebank```

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Suggests turbofish in patterns #114300

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bors commented Aug 3, 2023

		@@ -1,8 1,8 @@
		error: expected one of `:`, `@`, or `\|`, found `<`
		error: expected one of `!`, `(`, `...`, `..=`, `..`, `::`, `:`, `{`, or `\|`, found `<`

Suggests turbofish in patterns #114300

Suggests turbofish in patterns #114300

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