template-generating templates are not exported

[mfiano]

Example

import macros

type
  Storage[N: static[int]] = array[N, float32]
  Quat* = object
    data: Storage[4]
  
proc `[]`(q: Quat, index: int): float32 = q.data[index]
proc `[]=`(q: var Quat, index: int, value: float32) = q.data[index] = value

template genAccessor(t, a, i): untyped =
  template a*(q: t): float32 {.inject.} = q[i]
  template `a=`*(q: var t, value: float32) {.inject.} = q[i] = value

genAccessor Quat, w, 0
genAccessor Quat, x, 1
genAccessor Quat, y, 2
expandMacros:
  genAccessor Quat, z, 3

var a = Quat()
a.data = [1f,2,3,4]
a.x = 42.0
echo a

Current Output

Compiler output from expandMacros:

template z(q`gensym141121: Quat): float32 {.inject.} =
  q`gensym141121[3]

template z=(q`gensym141122: var Quat; value`gensym141123: float32) {.inject.} =
  []=(q`gensym141122, 3, value`gensym141123)

The generated templates are not usable outside of the current module. Making them procs instead preserves the export token.

Expected Output

template z*(q`gensym141121: Quat): float32 {.inject.} =
  q`gensym141121[3]

template `z=`*(q`gensym141122: var Quat; value`gensym141123: float32) {.inject.} =
  []=(q`gensym141122, 3, value`gensym141123)

Possible Solution

?

Additional Information

$ nim -v
Nim Compiler Version 1.0.6 [Linux: amd64]
Compiled at 2020-02-08
Copyright (c) 2006-2019 by Andreas Rumpf

[Varriount]

Note that this bug can be worked around with the (undocumented) dirty pragma.

[Araq]

It's documented here https://nim-lang.org/docs/manual.html#templates-hygiene-in-templates

I opened the manual, searched for "dirty" and found it immediately. Maybe the next time you can do the same, thanks.

[Varriount]

I'm aware of the mention in the manual. Unfortunately that's it though - it's not listed in the pragmas section, not does it have even a code block.

[Araq]

That only means that the docs are lacking, not that it's "undocumented".