nimforum mirror - What is missing for the seq/string types to be not nil by default?

Krux02 (orginal) [2017-07-27T19:22:54+02:00] view original

The title is the question. I would like to contribute, if I can (maybe).

Araq (orginal) [2017-07-27T21:26:41+02:00] view original

Optimizations aside, system.add and setLen need to be able to handle a nil seq and all the toString operations need to treat nil as the empty sequence. Note that len already returns 0 for nil. isNil needs to produce a compilation error for seqs and strings. The compiler should not allow to pass nil to strings/seqs. So ... internally there would still be nil, but it wouldn't be exposed. Implementation improvements could come later.

Krux02 (orginal) [2017-07-28T00:22:05+02:00] view original

well are you open for a pull request for that. I think that's easy to implement.

Krux02 (orginal) [2017-07-28T03:55:45+02:00] view original

well I did something in that direction on a branch. I have a problem with the nim compiler to crash here and there. How do I enable debug information again in the compiler? And why is is such a hassle in nim to get debug information? Debug builds should have them.

I have a stack trace, but unfortunately the bug non deterministic, and since I can't inspect anything with gdb, yea I don't know what to do.


Hint: used config file '/home/arne/proj/nim/Nim/config/nim.cfg' [Conf]
Hint: used config file '/home/arne/.config/nim.cfg' [Conf]
Hint: system [Processing]
Hint: scratch [Processing]
Traceback (most recent call last)
/home/arne/proj/nim/Nim/compiler/nim.nim(121) nim
/home/arne/proj/nim/Nim/compiler/nim.nim(77) handleCmdLine
/home/arne/proj/nim/Nim/compiler/main.nim(163) mainCommand
/home/arne/proj/nim/Nim/compiler/main.nim(75) commandCompileToC
/home/arne/proj/nim/Nim/compiler/cgen.nim(1429) cgenWriteModules
/home/arne/proj/nim/Nim/compiler/cgen.nim(1357) writeModule
/home/arne/proj/nim/Nim/compiler/cgen.nim(1130) genModule
/home/arne/proj/nim/Nim/compiler/cgen.nim(885) getFileHeader
/home/arne/proj/nim/Nim/compiler/cgen.nim(882) getCopyright
/home/arne/proj/nim/Nim/compiler/extccomp.nim(578) getCompileCFileCmd
/home/arne/proj/nim/Nim/lib/system/gc.nim(488) newObjNoInit
/home/arne/proj/nim/Nim/lib/system/alloc.nim(561) rawAlloc
SIGSEGV: Illegal storage access. (Attempt to read from nil?)

Parashurama (orginal) [2017-07-28T09:30:53+02:00] view original

If I understood your question correctly, you want to build a compiler with debugging info?

# this generate an additional compiler with debuging info
# and all checks enabled that will run quite a bit slower.
./koch temp --debugger:native

# run nim file with this debug compiler
nim_temp c -r --debugger:native --verbosity:3 (additional args) nimfile.nim

cdome (orginal) [2017-07-28T11:34:45+02:00] view original

Useful page https://github.com/nim-lang/Nim/wiki/Debugging-the-compiler

Krux02 (orginal) [2017-07-28T16:02:19+02:00] view original

Ok the problem is somewhere in the garbage collecter. It tries to create an object and fails. My motivation to fix issues with the GC is pretty low. I would spend my time rather on removing the dependency on the GC than to fix the problem with it.

bpr (orginal) [2017-07-28T16:53:04+02:00] view original

This may not be directly related to your goal, but under Future directions: we have that seq and string may get memory regions.

Krux02 (orginal) [2017-07-29T03:14:30+02:00] view original

Thank you, and yes it is related. When I touch code of strings, everything becomes important.

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3073 :: What is missing for the seq/string types to be not nil by default?