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13105 :: Weird compilation bug with table, deque and effects

• darkestpigeon (orginal) [2025-06-13T14:42:04+02:00] view original

  I have a weird compilation bug, here is the minimal snipped I've been able to produce:

  
  import std/[tables, deques]
  
  
  block:
    var x: Deque[proc() {.gcsafe.}]
    while x.len > 0:
      discard x.popFirst()
  
  block:
    type Fun = proc() {.gcsafe, raises: [].}
    
    var
      x: Table[int, Fun]
      y: Fun
    discard x.pop(0, y)
  Run

  The error is

  .choosenim/toolchains/nim-#devel/lib/pure/collections/tables.nim(557, 15) Error: type mismatch: got 'proc (){.closure, gcsafe.}' for 'move(t.data[index].val)' but expected 'Fun = proc (){.closure, gcsafe.}'
  .raise effects differ
  Run

  Getting the same error for both stable and devel. The error goes away if

  1. One of the blocks is removed
  2. Blocks are swapped
  3. raises is removed from block 2
  4. raises is added to block 1
  5. raises is moved from block 1 to block 2
  6. gcsafe is removed

  Don't even know how to name the issue on github :)

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