generics, checker: Wrong alias management in methods 1

[enghitalo]

Describe the bug

wrong checker error in methods

Reproduction Steps

pub struct User {
	name   string
	age    int
	height f64
}

type Users = map[string]User

fn (mut decoder Decoder) decode_map[K, V](mut val map[K]V) ! {
	assert true
}

struct Decoder {
}

pub fn decode[T](val string) !T {

	mut decoder := Decoder{
	}

	mut result := T{}
	$if T.unaliased_typ is $map {
		decoder.decode_map(mut result)!
	}

	return result
}

fn main() {
	assert decode[Users]('')! == Users(decode[map[string]User]('')!)
}

Expected Behavior

assert pass

Current Behavior

code.v:30:26: error: cannot use `Users` as `&map[Users]User` in argument 1 to `Decoder.decode_map`
   28 | fn (mut decoder Decoder) decode_value[T](mut val T) ! {
   29 |      $if T.unaliased_typ is $map {
   30 |         decoder.decode_map(mut val)!
      |                                ~~~
   31 |      } $else {
   32 |
Exited with error status 1
Please try again.

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.10 d629a01

Environment details (OS name and version, etc.)

Linux

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[huly-for-github]

Connected to Huly®: V_0.6-22404