Optional inference in match expression

[jorgeluismireles]

Describe the feature

This is an extension of issue #23827

Infer as possible the match cases for optionals

Use Case

For returning none we need explicity set ?int(none)

fn a(cond int) {
	v:= match cond {
		0 {
			?int(none)
		}
		1 {
			1
		}
		else {
			1000
		}
	}
	println('${v}')
}

a(2)

Proposed Solution

Infer the none from ?int(none) to have this simpler form:

fn a(cond int) {
	v:= match cond {
		0 {
			none
		}
		1 {
			1
		}
		else {
			1000
		}
	}
	println('${v}')
}

a(2)

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

Version used

V 0.4.9 5f5e48e

Environment details (OS name and version, etc.)

https://play.vlang.io/p/04cc0c924c

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[huly-for-github]

Connected to Huly®: V_0.6-22236

[jorgeluismireles]

Is worth to mention that when the match is returned by a function with its return specified, single none already works:

fn a(cond int) ?int {
	return match cond {
		0 {
			none
		}
		1 {
			1
		}
		else {
			1000
		}
	}
}
println('${a(2)}')