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3339 :: Comment causing compiler to fail?

• monster (orginal) [2017-11-15T22:57:51+01:00] view original

  I was trying to understand why my code fails to compile, and eventually reduced it enough to find out it is caused by a comment. Is that normal?

  # PART 1 : atomics_test1.nim
  type
    VolatilePtr*[T] = distinct ptr T
  
  proc toVolatilePtr*[T](t: var T): VolatilePtr[T] =
    cast[VolatilePtr[T]](addr t)
  
  when declared(atomicLoadN):
    proc atomicLoadNSeqCST*[T: AtomType](p: VolatilePtr[T]): T {.inline.} =
      atomicLoadN(cast[ptr[T]](p), ATOMIC_SEQ_CST)
      ## REMOVE ME!
  Run

  # PART 2 : atomics_test2.nim
  import atomics_test1
  
  var my_vbyte {.volatile.}: byte = 42'u8
  var my_vbyte_ptr: VolatilePtr[byte] = toVolatilePtr[byte](my_vbyte)
  
  assert(atomicLoadNSeqCST(my_vbyte_ptr) == 42'u8)
  Run

  The assert in PART 2 fails to compile, with message:

  atomics_test2.nim(7, 25) template/generic instantiation from here

  atomics_test1.nim(10, 16) Error: expression 'atomicLoadN(castptr [T], ATOMIC_SEQ_CST)' is of type 'byte' and has to be discarded

  The terminal process terminated with exit code: 1

  If I remove the comment "## REMOVE ME!" in PART 1, it works again!

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• mikra (orginal) [2017-11-15T23:23:35+01:00] view original

  looks to me like a bug. I encountered same strange effects (expecially within templates with/without return value). If your template returns nothing, it compiles without discard. Also (within the unit-test module) the compiler complains about unused variables (but they are used). Seems to me also related to templates. I tried to track it down to a minimalisic example but then the behaviour is away..

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• monster (orginal) [2017-11-18T15:46:40+01:00] view original

  I was about to post an issue to github for this, as I have a simple reproducible case, but a search in the issues turned this out: Manual should specify where documentation comments are allowed If I replace "## REMOVE ME!" with "# REMOVE ME!", it works.

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• mikra (orginal) [2017-11-18T20:26:36+01:00] view original

  many thanks, for posting this issue monster; this information is completely new to me.

  unfortunately it´s not stated here: https://nim-lang.org/docs/docgen.html#introduction-documentation-comments

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