Call to unwrapped `?&Fn` fails in if guard and iterator loops

[wenxuanjun]

Describe the bug

Calling a function pointer obtained from a ?&Fn (optional pointer to function) generates invalid C code when unwrapped via if guards or iterator loops for x in iter.

The C generator creates a double pointer void (**)(void) but attempts a direct call p(), causing a function pointer expected error. But unwrapping via or { return } works correctly.

Reproduction Steps

The if guard version compared to or { return } version:

type MyFn = fn()

fn hello() {}

fn get_ptr() ?&MyFn {
	return &hello
}

fn main() {
	if p := get_ptr() {
		p() // error: function pointer expected
	}

	p2 := get_ptr() or { return } // works
	p2() // OK
}

The iterator fails either:

type MyFn = fn()

struct Iter {
	f MyFn = fn(){}
mut:
	done bool
}

fn (mut it Iter) next() ?&MyFn {
	if it.done { return none }
	it.done = true
	return &it.f
}

fn main() {
	for p in Iter{} {
		p() // error: function pointer expected
	}
}

Expected Behavior

The if guard and iterator versions should compile and run.

Current Behavior

C compilation fails: error: function pointer expected

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.12 ecd0018

Environment details (OS name and version, etc.)

V 0.4.12 ecd0018

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[wenxuanjun]

@felipensp The unwrap on if guard is fixed, but the iterator still c error with function pointer expected. Should we reopen this issue?

[felipensp]

@felipensp The unwrap on if guard is fixed, but the iterator still c error with function pointer expected. Should we reopen this issue?

I'll take a look at it.