Description

When wrapping MAPR I wanted to test my hooks with Valgrind to make sure I had gotten them right. What I ended up with was finding a bug in the =copy hook for sequences placed in ref objects. The smallest reproduction I've been able to create is this:

type ElementKind* = enum String, Number Element* = object case kind*: ElementKind  of String: str*: string  of Number: num*: float Calc = ref object stack: seq[Element] var calc = new Calc calc.stack.add Element(kind: Number, num: 200.0) echo "Calc stack before: ", calc.stack echo "---" let calc2 = calc calc2.stack = calc.stack # This nulls out the object in the stack echo "Calc stack after: ", calc.stack echo "Calc2 stack after: ", calc2.stack

If a simple seq[int] is used the program behaves as expected. So it appears to only happen for more complex objects. The reason is that =copy is triggered on calc.stack to calc2.stack and the hook doesn't check if they are already equal.

Nim Version

Both 2.0.0 and the current devel

Current Output

Calc stack before: @[(kind: Number, num: 200.0)] --- Calc stack after: @[(kind: String, str: "")] Calc2 stack after: @[(kind: String, str: "")] 

Expected Output

Calc stack before: @[(kind: Number, num: 200.0)] --- Calc stack after: @[(kind: Number, num: 200.0)] Calc2 stack after: @[(kind: Number, num: 200.0)] 

Possible Solution

No response

Additional Information

No response