Mirror of forum.nim-lang.org

9185 :: Are user defined pragmas permitted in a let section with Nim 1.6?

• dxb (orginal) [2022-05-30T10:39:46+02:00] view original

  Greetings!

  The following code displays "Oh Hi" using the devel branch (1.7) but fails to compile using 1.6.6 (current stable). Is this expected? Thank you.

  macro ohhi(letSection: untyped): untyped =
      echo "Oh Hi"
      result = letSection
  
  proc test() =
      let
          t {. ohhi .} = 1
  
  test()
  Run

  Related to https://forum.nim-lang.org/t/9177#60198

---

• DavideGalilei (orginal) [2022-05-30T10:57:52+02:00] view original

  🤔 This example fails to compile too: /tmp/test.nim(8, 11) Error: invalid pragma: ohhi

  import macros
  
  macro ohhi(letSection: untyped): untyped =
    echo treeRepr letSection
    return letSection
  
  proc test() =
    let t {.ohhi, nodecl.} = 1
  
  test()
  Run

---

• ElegantBeef (orginal) [2022-05-30T11:13:49+02:00] view original

  They've had a change in #devel which causes them to work with a single statement whereas they used to require template ohhi(left, right, expr: untyped) for an example https://nim-lang.org/docs/decls.html#byaddr.t%2C%2C%2C

---

• dxb (orginal) [2022-05-30T13:46:34+02:00] view original

  Thank you @ElegantBeef. I find that Nim 1.7 errors out with `` Error: invalid pragma: ohhi`` when using macro ohhi(left, right, expr: untyped): untyped, so it seems that there isn't a single macro signature that would work for both Nim 1.6 and Nim 1.7 for this particular case.

---

• dxb (orginal) [2022-05-30T14:06:10+02:00] view original

  For reference I believe this is the relevant commit https://github.com/nim-lang/Nim/commit/2bd1aa186e09565b2103394bd281478fa1b10ef1

---