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Nonsensical suggested type using chumsky select! (E0284) #123630

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schrottkatze opened this issue Apr 8, 2024 · 5 comments · Fixed by #127160
Closed

Nonsensical suggested type using chumsky select! (E0284) #123630

schrottkatze opened this issue Apr 8, 2024 · 5 comments · Fixed by #127160
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A-diagnostics Area: Messages for errors, warnings, and lints D-invalid-suggestion Diagnostics: A structured suggestion resulting in incorrect code. E-needs-mcve Call for participation: This issue has a repro, but needs a Minimal Complete and Verifiable Example E-needs-test Call for participation: An issue has been fixed and does not reproduce, but no test has been added. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@schrottkatze
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Code

https://forge.katzen.cafe/schrottkatze/iowo/src/commit/bfd4b3765f35a98112b691d2f29c2c3446fe4d5c/crates/lang/src/parser.rs#L41-L44

Current output

error[E0284]: type annotations needed for `Select<{closure@/home/jade/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, I, Expression<'_>, E>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<{closure@/home/jade/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, I, Expression<'_>, E> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Desired output

No response

Rationale and extra context

This error is very confusing and unreadable, and the compiler even proposes adding a type containing a local path into the code.

That seems very problematic and incorrect.

Other cases

No response

Rust Version

rustc 1.77.0-nightly (190f4c961 2024-01-09)
binary: rustc
commit-hash: 190f4c96116a3b59b7de4881cfec544be0246d84
commit-date: 2024-01-09
host: x86_64-unknown-linux-gnu
release: 1.77.0-nightly
LLVM version: 17.0.6

Anything else?

No response

@schrottkatze schrottkatze added A-diagnostics Area: Messages for errors, warnings, and lints T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 8, 2024
@jieyouxu jieyouxu added C-bug Category: This is a bug. A-suggestion-diagnostics Area: Suggestions generated by the compiler applied by `cargo fix` E-needs-mcve Call for participation: This issue has a repro, but needs a Minimal Complete and Verifiable Example D-confusing Diagnostics: Confusing error or lint that should be reworked. D-invalid-suggestion Diagnostics: A structured suggestion resulting in incorrect code. labels Apr 8, 2024
@compiler-errors
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Try updating your nightly compiler and checking if it's still like that? You're using a nightly compiler from January.

@estebank
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estebank commented Apr 8, 2024

To second compiler-errors' comment, I know that there was a change in this suggestion sometime in the past month.

Edit: nevermind

// FIXME: The same thing for closures, but this only works when the closure
// does not capture anything.

estebank added a commit to estebank/rust that referenced this issue Apr 10, 2024
When suggesting a type on inference error, do not use `{closure@..}`.
Instead, replace with an appropriate `fn` ptr.

On the error message, use `short_ty_string` and write long types to
disk.

```
error[E0284]: type annotations needed for `Select<{[email protected]:2782:13}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt'
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

instead of

```
error[E0284]: type annotations needed for `Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _> = select! {
   |                ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

Fix rust-lang#123630.
estebank added a commit to estebank/rust that referenced this issue Apr 10, 2024
When suggesting a type on inference error, do not use `{closure@..}`.
Instead, replace with an appropriate `fn` ptr.

On the error message, use `short_ty_string` and write long types to
disk.

```
error[E0284]: type annotations needed for `Select<{[email protected]:2782:13}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt'
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

instead of

```
error[E0284]: type annotations needed for `Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _> = select! {
   |                ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

Fix rust-lang#123630.
@estebank estebank self-assigned this Apr 10, 2024
fmease added a commit to fmease/rust that referenced this issue Apr 10, 2024
Use `fn` ptr signature instead of `{closure@..}` in infer error

When suggesting a type on inference error, do not use `{closure@..}`. Instead, replace with an appropriate `fn` ptr.

On the error message, use `short_ty_string` and write long types to disk.

```
error[E0284]: type annotations needed for `Select<{[email protected]:2782:13}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt'
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

instead of

```
error[E0284]: type annotations needed for `Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _> = select! {
   |                ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

Address rust-lang#123630 (test missing).
@estebank
Copy link
Contributor

Output with the PR linked above:

error[E0284]: type annotations needed for `Select<{[email protected]:2782:13}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt'
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

We still need a minimal repro to add a test to the test suite.

fmease added a commit to fmease/rust that referenced this issue Apr 10, 2024
Use `fn` ptr signature instead of `{closure@..}` in infer error

When suggesting a type on inference error, do not use `{closure@..}`. Instead, replace with an appropriate `fn` ptr.

On the error message, use `short_ty_string` and write long types to disk.

```
error[E0284]: type annotations needed for `Select<{[email protected]:2782:13}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt'
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

instead of

```
error[E0284]: type annotations needed for `Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _> = select! {
   |                ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

Address rust-lang#123630 (test missing).
fmease added a commit to fmease/rust that referenced this issue Apr 10, 2024
Use `fn` ptr signature instead of `{closure@..}` in infer error

When suggesting a type on inference error, do not use `{closure@..}`. Instead, replace with an appropriate `fn` ptr.

On the error message, use `short_ty_string` and write long types to disk.

```
error[E0284]: type annotations needed for `Select<{[email protected]:2782:13}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt'
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

instead of

```
error[E0284]: type annotations needed for `Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _> = select! {
   |                ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

Address rust-lang#123630 (test missing).
@bors bors closed this as completed in 796be88 Apr 11, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Apr 11, 2024
Rollup merge of rust-lang#123703 - estebank:diag-changes-2, r=Nadrieril

Use `fn` ptr signature instead of `{closure@..}` in infer error

When suggesting a type on inference error, do not use `{closure@..}`. Instead, replace with an appropriate `fn` ptr.

On the error message, use `short_ty_string` and write long types to disk.

```
error[E0284]: type annotations needed for `Select<{[email protected]:2782:13}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt'
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

instead of

```
error[E0284]: type annotations needed for `Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _> = select! {
   |                ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

Address rust-lang#123630 (test missing).
@estebank
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Needs test.

@estebank estebank reopened this Apr 13, 2024
@estebank estebank added E-needs-test Call for participation: An issue has been fixed and does not reproduce, but no test has been added. and removed C-bug Category: This is a bug. A-suggestion-diagnostics Area: Suggestions generated by the compiler applied by `cargo fix` D-confusing Diagnostics: Confusing error or lint that should be reworked. labels Apr 13, 2024
@pacak
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pacak commented Jun 30, 2024

Minimized reproduction in 1.77 nightly

struct Select<F, I>(F, I);

fn select<F, I>(filter: F) -> Select<F, I> {

}

fn parser1() {
    let lit = select(|x| match x {
        _ => (),
    });
}
% rustc --version
rustc 1.77.0-nightly (ca663b06c 2024-01-08)
error[E0308]: mismatched types
 --> src/lib.rs:3:31
  |
3 | fn select<F, I>(filter: F) -> Select<F, I> {
  |    ------                     ^^^^^^^^^^^^ expected `Select<F, I>`, found `()`
  |    |
  |    implicitly returns `()` as its body has no tail or `return` expression
  |
  = note: expected struct `Select<F, I>`
          found unit type `()`

error[E0282]: type annotations needed for `Select<{closure@src/lib.rs:8:22: 8:25}, I>`
 --> src/lib.rs:8:9
  |
8 |     let lit = select(|x| match x {
  |         ^^^
  |
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
  |
8 |     let lit: Select<{closure@src/lib.rs:8:22: 8:25}, I> = select(|x| match x {
  |            ++++++++++++++++++++++++++++++++++++++++++++

Some errors have detailed explanations: E0282, E0308.
For more information about an error, try `rustc --explain E0282`.

pacak added a commit to pacak/rust that referenced this issue Jun 30, 2024
compiler should not suggest nonsensical signatures, original suggestion was

error[E0308]: mismatched types
 --> src/lib.rs:3:31
  |
3 | fn select<F, I>(filter: F) -> Select<F, I> {
  |    ------                     ^^^^^^^^^^^^ expected `Select<F, I>`, found `()`
  |    |
  |    implicitly returns `()` as its body has no tail or `return` expression
  |
  = note: expected struct `Select<F, I>`
          found unit type `()`

error[E0282]: type annotations needed for `Select<{closure@src/lib.rs:8:22: 8:25}, I>`
 --> src/lib.rs:8:9
  |
8 |     let lit = select(|x| match x {
  |         ^^^
  |
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
  |
8 |     let lit: Select<{closure@src/lib.rs:8:22: 8:25}, I> = select(|x| match x {
  |            ++++++++++++++++++++++++++++++++++++++++++++

Some errors have detailed explanations: E0282, E0308.
For more information about an error, try `rustc --explain E0282`.
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Jun 30, 2024
Add a regression test for rust-lang#123630

Fixes rust-lang#123630

compiler should not suggest nonsensical signatures, original suggestion was

```
error[E0308]: mismatched types
 --> src/lib.rs:3:31
  |
3 | fn select<F, I>(filter: F) -> Select<F, I> {
  |    ------                     ^^^^^^^^^^^^ expected `Select<F, I>`, found `()`
  |    |
  |    implicitly returns `()` as its body has no tail or `return` expression
  |
  = note: expected struct `Select<F, I>`
          found unit type `()`

error[E0282]: type annotations needed for `Select<{closure@src/lib.rs:8:22: 8:25}, I>`
 --> src/lib.rs:8:9
  |
8 |     let lit = select(|x| match x {
  |         ^^^
  |
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
  |
8 |     let lit: Select<{closure@src/lib.rs:8:22: 8:25}, I> = select(|x| match x {
  |            ++++++++++++++++++++++++++++++++++++++++++++

Some errors have detailed explanations: E0282, E0308. For more information about an error, try `rustc --explain E0282`.
```
bors added a commit to rust-lang-ci/rust that referenced this issue Jun 30, 2024
…iaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#126018 (Remove the `box_pointers` lint.)
 - rust-lang#126895 (Fix simd_gather documentation)
 - rust-lang#126981 (Replace some magic booleans in match-lowering with enums)
 - rust-lang#127069 (small correction to fmt::Pointer impl)
 - rust-lang#127157 (coverage: Avoid getting extra unexpansion info when we don't need it)
 - rust-lang#127160 (Add a regression test for rust-lang#123630)
 - rust-lang#127161 (Improve `run-make-support` library `args` API)
 - rust-lang#127162 (Subtree sync for rustc_codegen_cranelift)

r? `@ghost`
`@rustbot` modify labels: rollup
bors added a commit to rust-lang-ci/rust that referenced this issue Jun 30, 2024
…iaskrgr

Rollup of 9 pull requests

Successful merges:

 - rust-lang#126018 (Remove the `box_pointers` lint.)
 - rust-lang#126895 (Fix simd_gather documentation)
 - rust-lang#126981 (Replace some magic booleans in match-lowering with enums)
 - rust-lang#127038 (Update test comment)
 - rust-lang#127053 (Update the LoongArch target documentation)
 - rust-lang#127069 (small correction to fmt::Pointer impl)
 - rust-lang#127157 (coverage: Avoid getting extra unexpansion info when we don't need it)
 - rust-lang#127160 (Add a regression test for rust-lang#123630)
 - rust-lang#127161 (Improve `run-make-support` library `args` API)

r? `@ghost`
`@rustbot` modify labels: rollup
bors added a commit to rust-lang-ci/rust that referenced this issue Jun 30, 2024
…iaskrgr

Rollup of 9 pull requests

Successful merges:

 - rust-lang#126018 (Remove the `box_pointers` lint.)
 - rust-lang#126895 (Fix simd_gather documentation)
 - rust-lang#126981 (Replace some magic booleans in match-lowering with enums)
 - rust-lang#127038 (Update test comment)
 - rust-lang#127053 (Update the LoongArch target documentation)
 - rust-lang#127069 (small correction to fmt::Pointer impl)
 - rust-lang#127157 (coverage: Avoid getting extra unexpansion info when we don't need it)
 - rust-lang#127160 (Add a regression test for rust-lang#123630)
 - rust-lang#127161 (Improve `run-make-support` library `args` API)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors closed this as completed in 6335b83 Jun 30, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Jun 30, 2024
Rollup merge of rust-lang#127160 - pacak:123630-test, r=Nadrieril

Add a regression test for rust-lang#123630

Fixes rust-lang#123630

compiler should not suggest nonsensical signatures, original suggestion was

```
error[E0308]: mismatched types
 --> src/lib.rs:3:31
  |
3 | fn select<F, I>(filter: F) -> Select<F, I> {
  |    ------                     ^^^^^^^^^^^^ expected `Select<F, I>`, found `()`
  |    |
  |    implicitly returns `()` as its body has no tail or `return` expression
  |
  = note: expected struct `Select<F, I>`
          found unit type `()`

error[E0282]: type annotations needed for `Select<{closure@src/lib.rs:8:22: 8:25}, I>`
 --> src/lib.rs:8:9
  |
8 |     let lit = select(|x| match x {
  |         ^^^
  |
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
  |
8 |     let lit: Select<{closure@src/lib.rs:8:22: 8:25}, I> = select(|x| match x {
  |            ++++++++++++++++++++++++++++++++++++++++++++

Some errors have detailed explanations: E0282, E0308. For more information about an error, try `rustc --explain E0282`.
```
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A-diagnostics Area: Messages for errors, warnings, and lints D-invalid-suggestion Diagnostics: A structured suggestion resulting in incorrect code. E-needs-mcve Call for participation: This issue has a repro, but needs a Minimal Complete and Verifiable Example E-needs-test Call for participation: An issue has been fixed and does not reproduce, but no test has been added. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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