Returning error in Option type ?

[impopular-guy]

I can do the following on an Option type

mut a := ?int(5)
a = 1
a = none

I can also do this

fn func() ?int {
	return error('Some error')
}
a = func()

However, I get builder error if I try to directly assign the error

a = error('Some error')

Questions:

The docs say that Option types may represent none and Result may represent error. So I was under the impression that error
cannot be passed when we have Option return type, since Option/Result was separated a while ago. I was able to put error in the option type.
Also the C code tells that none is just an IError. This might be useful when we want to return none as well as error from same
function, but here we will have to manually check and propagate errors.

• Is this expected behaviour?
• Is a = error('Some error') a bug? Of course it is because its a builder error. But should such be allowed?

[JalonSolov]

It's expected for now, since V used to only support a single type that could return either none or an error. This is deprecated, and due to be removed this year, but is still active for now to avoid breaking code.

Directly assigning an error to a variable is an error, not a bug. Errors don't have types that can be assigned, they can only be checked in or blocks.

[impopular-guy]

Understood.

What to do in this situation: I have a function A that returns Option type but inside it it calls another func B that returns result type and I wish to propagate the error.

Out of curiosity i tried:

fn func() !?int {  // also ?!int
	return 0
}

This was showing some weird errors. https://play.vlang.io/p/007db98ae4

[JalonSolov]

!?/?! is invalid syntax. At least after the deprecation, you will be able to return an Option or a Result, but not both.

[medvednikov]

It should result in a warning about the split, will fix.