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

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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