Generic argument span for function type is incorrect

[varkor]

rust/src/test/ui/unboxed-closures/unboxed-closure-sugar-wrong-trait.stderr

Lines 1 to 5 in 1558ae7

	error[E0244]: wrong number of type arguments: expected 0, found 1
	--> $DIR/unboxed-closure-sugar-wrong-trait.rs:15:13
	|
	LL | fn f<F:Trait(isize) -> isize>(x: F) {}
	| ^^^^^^^^^^^^^^^^ unexpected type argument

The unexpected type argument here should be just isize (it should end at the )). This syntax is just for function arguments, so it's probably something to do with the desugaring.