rust/tests/ui/traits/copy-guessing.rs
Esteban Küber 796be88062 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<{closure@lib.rs: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 #123630.
2024-04-10 00:41:27 +00:00

41 lines
1.0 KiB
Rust

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