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https://github.com/rust-lang/rust
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796be88062
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<{closure@lib.rs:2782:13}, _, Expression<'_>, _>`
--> crates/lang/src/parser.rs:41:13
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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
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= 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
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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
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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 #123630.
41 lines
1 KiB
Rust
41 lines
1 KiB
Rust
#![allow(dead_code)]
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#![allow(dropping_copy_types)]
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// "guessing" in trait selection can affect `copy_or_move`. Check that this
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// is correctly handled. I am not sure what is the "correct" behaviour,
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// but we should at least not ICE.
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use std::mem;
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struct U([u8; 1337]);
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struct S<'a,T:'a>(&'a T);
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impl<'a, T> Clone for S<'a, T> { fn clone(&self) -> Self { S(self.0) } }
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/// This impl triggers inference "guessing" - S<_>: Copy => _ = U
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impl<'a> Copy for S<'a, Option<U>> {}
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fn assert_impls_fn<R,T: Fn()->R>(_: &T){}
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fn main() {
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let n = None;
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//~^ ERROR type annotations needed for `Option<_>`
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let e = S(&n);
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let f = || {
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// S being copy is critical for this to work
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drop(e);
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mem::size_of_val(e.0)
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};
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assert_impls_fn(&f);
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assert_eq!(f(), 1337+1);
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assert_eq!((|| {
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// S being Copy is not critical here, but
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// we check it anyway.
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let n = None;
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let e = S(&n);
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let ret = mem::size_of_val(e.0);
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drop(e);
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ret
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})(), 1337+1);
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}
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