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Description
I tried this code:
fn foo() {}
fn bar() {}
fn main() {
let _a = if true { foo } else { bar };
let _b = vec![foo, bar];
let _c = [foo, bar];
d(if true { foo } else { bar });
e(vec![foo, bar]);
f([foo, bar]);
}
fn d<T>(_: T) {}
fn e<T>(_: Vec<T>) {}
fn f<T>(_: [T; 2]) {}I expected the six lines to either all compile or all error. Instead, only the f([foo, bar]) line fails, with the following error:
error[E0308]: mismatched types
--> src/main.rs:10:7
|
10 | f([foo, bar]);
| - ^^^^^^^^^^ expected `[fn() {foo}; 2]`, found `[fn(); 2]`
| |
| arguments to this function are incorrect
|
= note: expected array `[fn() {foo}; 2]`
found array `[fn(); 2]`
note: function defined here
--> src/main.rs:15:4
|
15 | fn f<T>(_: [T; 2]) {}
| ^ ---------
For more information about this error, try `rustc --explain E0308`.
For some reason, it's failing to coerce the function items into function pointers, but only when an array is being passed to a generic function.
Discovered by @xero-lib
Meta
Issue reproducible on the playground with stable rust 1.84.1, and nightly rust 1.86.0-nightly (2025-02-01 8239a37f9c0951a037cf)
@rustbot labels +A-inference +A-coercions