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6585 :: What code is affected by runtime check pragmas?

• sschwarzer (orginal) [2020-07-23T23:27:57+02:00] view original

  I know I can use -d:danger to deactivate runtime checks for the whole program, but let's assume I usually want the checks, but only deactivate them for a certain section of my code.

  The manual describes pragmas to do this, so I can write

  proc f() =
    {.push checks: off.}
    ...
    {.pop.}
  Run

  Now, does the pragma only affect the code that is visible between the push and pop pragmas? In other words, in

  proc g() =
    ...
  
  proc f() =
    {.push checks: off.}
    ...
    g()
    ...
    {.pop.}
  Run

  are the runtime checks also deactivated for g? Is there are difference if g is a template or macro?

  If the pragmas affect also called code, this would mean that

  proc g() =
    ...
  
  proc f1() =
    {.push checks: off.}
    ...
    g()
    ...
    {.pop.}
  
  proc f2() =
    ...
    g()
    ...
  Run

  generates two versions of g, one without runtime checks (called from f1) and one with runtime checks (called from f2). Correct?

  If the compiler can indeed generate different versions of a proc depending on pragmas, does this also extend to code in other modules (for example, if I call code in algorithms that actually does most of the work in my proc)?

  One extra question, not directly related to the one above: Is there a difference in the generated code for

  # Pragmas inside the proc
  proc f() =
    {.push checks: off.}
    ...
    {.pop.}
  Run

  vs.

  # Pragmas outside the proc
  {.push checks: off.}
  proc f() =
    ...
  {.pop.}
  Run

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• juancarlospaco (orginal) [2020-07-23T23:40:55+02:00] view original

  I think it depends, if it is template or macro or proc or proc {.inline.}. But "normal" proc outside push/pop should not be affected. You can try using macros.expandMacros and friends.

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• DeletedUser (orginal) [2020-07-24T03:40:36+02:00] view original

  are the runtime checks also deactivated for g? Is there a difference if g is a template or macro?

  No, yes. Templates/macros "insert" the code into the proc so it is affected by the checks, whereas proc calls merely call already generated code elsewhere, in this case g was not instantiated with checks: off so it will have checks on inside it. Nim cannot track these pragma changes and generate a new proc every time.

  One extra question, not directly related to the one above: Is there a difference in the generated code for

  I see no reason for there to be a difference

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