Inline increment on non-existing dict keys?

[phorward]

This bug raised within the aoc2024.tok repository, day 1.

Simplest test-case:

d = ()
d[0] = 1
d[0]++
# d[1] = 0  # FIX
d[1]++  # d[1] does not exist!
print(d)  # prints only "(0 => 2)", expected (0 => 2 1 => 1)

The problem is, that Op::LoadItem pushes void, and void is being modified, and afterwards cleared

__main__      ip = 2 state = Ok(Push([578deca8df88] 1 (10)))
__main__      --- Code ---
__main__       000 LoadGlobal(0)
__main__       001 Offset(Offset { offset: 2, row: 1, col: 3 })
__main__       002 Push1
__main__      >003 LoadItem
__main__       004 Offset(Offset { offset: 0, row: 1, col: 1 })
__main__       005 Dup
__main__       006 Swap(2)
__main__       007 UnaryOp("iinc")
__main__       008 Drop
__main__      --- Reader ---
__main__       offset=Offset { offset: 0, row: 1, col: 1 }
__main__       eof=false
__main__      --- Globals ---
__main__       000 Object(Dict { dict: {} })
__main__      --- Stack ---
__main__       000 [578decb12768] () (10)
__main__       001 [578deca8df88] 1 (10)
__main__      --- Frames ---
__main__       000 capture: 0, reader: 0, fuse: None

__main__      ip = 3 state = Ok(Push([578dec8ac9f8] void (10)))
__main__      --- Code ---
__main__       000 LoadGlobal(0)
__main__       001 Offset(Offset { offset: 2, row: 1, col: 3 })
__main__       002 Push1
__main__       003 LoadItem
__main__       004 Offset(Offset { offset: 0, row: 1, col: 1 })
__main__      >005 Dup
__main__       006 Swap(2)
__main__       007 UnaryOp("iinc")
__main__       008 Drop
__main__      --- Reader ---
__main__       offset=Offset { offset: 0, row: 1, col: 1 }
__main__       eof=false
__main__      --- Globals ---
__main__       000 Object(Dict { dict: {} })
__main__      --- Stack ---
__main__       000 [578dec8ac9f8] void (10)
__main__      --- Frames ---
__main__       000 capture: 0, reader: 0, fuse: None
.
.
.
__main__      ip = 7 state = Ok(Push([578dec8ac9f8] 1 (10)))
__main__      --- Code ---
__main__       000 LoadGlobal(0)
__main__       001 Offset(Offset { offset: 2, row: 1, col: 3 })
__main__       002 Push1
__main__       003 LoadItem
__main__       004 Offset(Offset { offset: 0, row: 1, col: 1 })
__main__       005 Dup
__main__       006 Swap(2)
__main__       007 UnaryOp("iinc")
__main__      >008 Drop
__main__      --- Reader ---
__main__       offset=Offset { offset: 0, row: 1, col: 1 }
__main__       eof=false
__main__      --- Globals ---
__main__       000 Object(Dict { dict: {} })
__main__      --- Stack ---
__main__       000 [578deca8df88] void (10)
__main__       001 [578dec8ac9f8] 1 (10)
__main__      --- Frames ---
__main__       000 capture: 0, reader: 0, fuse: None

Generally, the iinc works as expected, but it works with a void value being copied, incremented and dropped. A possible solution would be something like a Op::LoadItemWithDefault that is being used in the iinc code generation.