Mutable sum types passed to a function can't be modified

[jorgeluismireles]

Describe the bug

We pass mutable sum types to a function to update the types fields and cannot be modified.

Reproduction Steps

struct Int { mut: i int }

struct String { mut: s string }

type Sum = Int | String

fn init(mut s Sum) {
	match mut s {
		Int    { s.i = 0 }
		String { s.s = '' }
	}
}

fn init_int(mut i Int) {
	i.i = 0
}

fn main() {
	mut i := Int{ i: 333 }
	mut s := String{ s: 'string' }
	init(mut i)
	init(mut s)
	println('${i.i}') // prints 333, should be 0
	println('${s.s}') // prints 'string', should be ''
	init_int(mut i)
	println('${i.i}') // prints 0 as expected
}

Function init above tries to initialize every sum type received but can't do it. Function init_int works.

Expected Behavior

Mutable fields passed to init function should be set to zero for integer sum type and empty for string sum type.

Current Behavior

Mutable fields passed to init function are not set to 0 or empty string.

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.9 86bb2d7

Environment details (OS name and version, etc.)

https://play.vlang.io/p/cfbb7907ac

Note

You can use the 👍 reaction to increase the issue's priority for developers.

Please note that only the 👍 reaction to the issue itself counts as a vote.
Other reactions and those to comments will not be taken into account.

[huly-for-github]

Connected to Huly®: V_0.6-22377

[felipensp]

Good catch. 👍🏻

[spytheman]

@jorgeluismireles I'll merge the PR with the fix, but I'll leave the issue opened, since we need to bootstrap the compiler first.
After a few more PRs, I will close the issue