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6892 :: -d:danger versus -d:release --checks:off

• slonik_az (orginal) [2020-10-05T14:51:06+02:00] view original

  I am curious when should I use -d:danger and when the combination -d:release --checks:off ? According to nim compiler documentation they serve similar purposes -- disabling the checks and enabling optimization.

  --Leo

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• Yardanico (orginal) [2020-10-05T15:02:02+02:00] view original

  You can check https://github.com/nim-lang/Nim/blob/devel/config/nim.cfg#L55 and see that -d:danger indeed disables all checks

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• slonik_az (orginal) [2020-10-05T15:08:24+02:00] view original

  Yes, -d:danger disables all the checks (and enables optimization). The question: Is it equivalent to -d:release --checks:off ?

  --Leo

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• DeletedUser (orginal) [2020-10-05T21:33:37+02:00] view original

  No, --checks:off only turns off checks, -d:danger also turns off assertions as well as checks in regards to -d:release as you can see in that config file.

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• slonik_az (orginal) [2020-10-05T23:07:50+02:00] view original

  --checks:off also turns off assertions (optAssert) as one can see in definition of ChecksOptions in

  https://github.com/nim-lang/Nim/blob/4e438f9096fc413824bdbe8377a4ca376d63be35/compiler/options.nim#L370

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• pietroppeter (orginal) [2020-10-06T01:11:58+02:00] view original

  From comparison of the above resources and factoring in also:

  https://github.com/nim-lang/Nim/blob/531ed2dc365d6d33c7bccdfbe22df561cf14af86/compiler/commands.nim#L394

  both in danger and checks:off

  • obj_checks:optObjCheck
  • field_checks:optFieldCheck
  • range_checks:optRangeCheck
  • bound_checks:optBoundsCheck
  • overflow_checks:optOverflowCheck
  • assertions:optAssert

  only in danger

  • stacktrace:off
  • linetrace:off
  • debugger:off
  • line_dir:off
  • dead_code_elim:on # deprecated, dead code elim always on
  • nilchecks:off # discard "no such thing anymore"

  only in checks:off

  • optNaNCheck
  • optInfCheck
  • optStyleCheck

  tentative conclusions

  • "-d:danger" adds to "-d:release --checks:off" removal of debugging stuff (stacktrace, linetrace, debugger, line_dir)
  • with "-d:danger" you do have style check on (but it does not affect runtime) but keep having float checks (NaNCheck, InfCheck) off, since they are not on by default (as can be seen by checking const DefaultOptions in compiler/options.nim)

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• slonik_az (orginal) [2020-10-06T01:45:24+02:00] view original

  Wait, -d:release already removes stacktrace, excessiveStackTrace, linetrace, debugger, line_dir and adds opt:speed, define:release.

  https://github.com/nim-lang/Nim/blob/4e438f9096fc413824bdbe8377a4ca376d63be35/config/nim.cfg#L72

  It seems that -d:danger is very similar -d:release --checks:off with optNaNCheck, optInfCheck, being possibly different.

  To get a definitive answer, can one dump the list of all options in effect for a given nim compilation run?

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• pietroppeter (orginal) [2020-10-06T02:30:36+02:00] view original

  ach, you are right!

  then I guess that -d:danger and -d:release --checks:off are the same except for StyleCheck (I still see no reason to doubt that optNanCheck and optInfCheck are off by default so there should be no difference there).

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• Araq (orginal) [2020-10-06T08:43:56+02:00] view original

  To get a definitive answer...

  Well people read the source code successfully. Can't get more definite than that. :-)

  But yeah, danger is release + checks:off. And the default config should probably be simplified to use --checks:off.

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• slonik_az (orginal) [2020-10-06T16:12:34+02:00] view original

  Well people read the source code successfully. Can't get more definite than that. :-)

  Well, as you can see from this thread several people read the same code and arrived at different conclusions :-) The definite answer is how compiler reads the code :-)

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• shirleyquirk (orginal) [2020-10-06T16:26:45+02:00] view original

  Good god if we can't know how the compiler reads code we should all go home

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• Arrrrrrrrr (orginal) [2020-10-07T12:55:19+02:00] view original

  But yeah, danger is release + checks:off. And the default config should probably be simplified to use --checks:off.

  Lots of projects ask the user to use both of them, there is a lot of misconceptions out there, for example https://github.com/mratsim/Arraymancer#performance-notice-on-nim-020--compilation-flags

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• Stefan_Salewski (orginal) [2020-10-07T13:15:05+02:00] view original

  Lots of projects ask the user to use both of them, there is a lot of misconceptions

  That was due to a bug in Nim before 1.0.

  I hope for beginners my explanation is good enough?

  http://ssalewski.de/nimprogramming.html#_launching_the_compiler_and_running_the_program

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