Repository navigation
mismatched types: expected fn&() -> ! but found fn&() -> _|_ #3681
Description
This fails:
fn foo(f: fn() -> !) {}
fn main() {
foo(|| {fail });
}
with
foo.rs:4:7: 4:18 error: mismatched types: expected `fn&() -> !` but found `fn&() -> _|_` (expected non-returning function, found non-returning function)
foo.rs:4 foo(|| {fail });
^~~~~~~~~~~
While this works:
fn foo(f: fn() -> !) {}
fn main() {
foo(fn() -> ! { fail });
}
I don't know what is going on there but I feel the first snippet should work too.
Activity
nikomatsakis commentedon Oct 8, 2012
Agreed. The current type checker has two ways to represent the same thing, which I think is what is leading to this problem. I've been thinking we oughta' fix that for some time, this bug gives me a good justification. =)
nikomatsakis commentedon Oct 8, 2012
Specifically: fn types have a
return_style(or something like that) and there is the bottom type. I don't see why we need both.catamorphism commentedon Jan 3, 2013
The reason we have both is that
_|_isn't a first-class type at the moment. That is, you can only mention it in the return type of a function, as!; you can't declare a local with type_|_, or a field in a data structure.catamorphism commentedon Jan 3, 2013
The most conservative fix here would be a way to infer the
return_stylefor closures.Remove ret_style and instead check whether fn return type is bot
Remove ret_style and instead check whether fn return type is bot
nikomatsakis commentedon Jan 8, 2013
This should be fixed.
Auto merge of rust-lang#3681 - rust-lang:rustup-2024-06-17, r=RalfJung
Merge rust-lang#3681