File: normalize-param-env-4.rs

package info (click to toggle)
rustc 1.85.0%2Bdfsg2-3
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid, trixie
  • size: 893,176 kB
  • sloc: xml: 158,127; python: 35,830; javascript: 19,497; cpp: 19,002; sh: 17,245; ansic: 13,127; asm: 4,376; makefile: 1,051; lisp: 29; perl: 29; ruby: 19; sql: 11
file content (35 lines) | stat: -rw-r--r-- 999 bytes parent folder | download | duplicates (6)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[next] compile-flags: -Znext-solver
//@[next] known-bug: #92505
//@[current] check-pass

trait Trait {
    type Assoc;
}

impl<T> Trait for T {
    type Assoc = T;
}

fn impls_trait<T: Trait>() {}

fn foo<T>()
where
    <T as Trait>::Assoc: Trait,
{
    // Trying to use `<T as Trait>::Assoc: Trait` to prove `T: Trait`
    // requires normalizing `<T as Trait>::Assoc`. We do not normalize
    // using impl candidates if there's a where-bound for that trait.
    //
    // We therefore check whether `T: Trait` is proven by the environment.
    // For that we try to apply the `<T as Trait>::Assoc: Trait` candidate,
    // trying to normalize its self type results in overflow.
    //
    // In the old solver we eagerly normalize the environment, ignoring the
    // unnormalized `<T as Trait>::Assoc: Trait` where-bound when normalizing
    // `<T as Trait>::Asosc`
    impls_trait::<T>();
}

fn main() {}