proc(x: var X | ref X) fails to compile

[kierdavis]

The following code compiles:

type
  MyObject = object
    x: int

proc doSomething(obj: var MyObject) =
  obj.x = 123

proc doSomething(obj: ref MyObject) =
  obj.x = 123

let refObj = MyObject.new
doSomething(refObj)
echo $refObj.x

var varObj = MyObject(x: 0)
doSomething(varObj)
echo $varObj.x

while the following code does not:

type
  MyObject = object
    x: int

proc doSomething(obj: var MyObject | ref MyObject) =
  obj.x = 123

let refObj = MyObject.new
doSomething(refObj)
echo $refObj.x

var varObj = MyObject(x: 0)
doSomething(varObj)
echo $varObj.x

instead giving the following compilation error:

test.nim(13, 12) template/generic instantiation from here
test.nim(6, 6) Error: 'obj.x' cannot be assigned to

[stale]

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[shirleyquirk]

seems reasonable that that should compile. bumping.

[Araq]

The mutability aspect of a type is not lifted to an "or" type. This is not a bug, but it could be a feature that we support. I personally don't like it at all, it's only useful for confused code that uses both var and ref and cannot make up its mind.