Inner proc in macro breaks parameters

[copygirl]

When using a static parameter in an inner proc of a macro, that parameter will somehow have the value 0 (if using static[int]) instead of the value passed to the macro.

edit: @zah mentioned this happens for nim nodes, too.

Example

import macros

macro foo(i: static[int]): untyped =
  echo $i

foo(1)
foo(2)

macro foo2(i: static[int]): untyped =
  echo $i
  proc doNothing() =
    discard i
  doNothing()

foo2(1)
foo2(2)

Current Output

1
2
0
0

Expected Output

1
2
1
2

Workaround

Can be avoided by assigning to a local variable first.

macro foo2(i: static[int]): untyped =
  let i2 = i
  echo $i2
  proc doNothing() =
    discard i2
  doNothing()

[zah]

This is not limited to static parameters. Regular AST parameters will be read as nil too if you don't re-assign them to a variable.

[kaushalmodi]

/cc @narimiran Was it you who pasted an example on the IRC where for an AST var e, you had to first assign e[0] to a new var e0, and so on .. ?

[narimiran]

Yes, it was me. (Nice memory! :))

Here is the full example:

macro with(obj: MyObject, body: untyped): untyped =
  result = newStmtList()
  for b in body:
    let
      b0 = b[0]
      b1 = b[1]
    result.add quote do:
      # `obj`.`b[0]` = `b[1]`
      `obj`.`b0` = `b1`

We cannot do the thing that is commented out, so we must introduce b0 and b1.

[timotheecour]

maybe also a fix for this would test for bug from closed as duplicate issue #9656 :

BUG: code below prints forwardResult1:false instead of forwardResult1:true

macro dispatchGen7*(forwardResult: static bool = true): untyped =
  echo "forwardResult1:", forwardResult # BUG: will show: forwardResult1:false
  proc callWrapped(): NimNode =
    let ignore = forwardResult # comment this => will show: forwardResult1:true
    discard

  let callWrapd=callWrapped()

dispatchGen7(forwardResult=true)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. If you think it is still a valid issue, write a comment below; otherwise it will be closed. Thank you for your contributions.

[Clyybber]

Still an issue..