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
|
// This test verifies that never type fallback preserves the following code in a
// compiling state. This pattern is fairly common in the wild, notably seen in
// wasmtime v0.16. Typically this is some closure wrapper that expects a
// collection of 'known' signatures, and -> ! is not included in that set.
//
// This test is specifically targeted by the unit type fallback when
// encountering a set of obligations like `?T: Foo` and `Trait::Projection =
// ?T`. In the code below, these are `R: Bar` and `Fn::Output = R`.
//
//@ revisions: nofallback fallback
//@ check-pass
#![cfg_attr(fallback, feature(never_type_fallback))]
trait Bar {}
impl Bar for () {}
impl Bar for u32 {}
fn foo<R: Bar>(_: impl Fn() -> R) {}
fn main() {
//[nofallback]~^ warn: this function depends on never type fallback being `()`
//[nofallback]~| warn: this was previously accepted by the compiler but is being phased out; it will become a hard error in Rust 2024 and in a future release in all editions!
foo(|| panic!());
}
|
