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7297 :: compiling to js but failed, generics not supported?

• jiyinyiyong (orginal) [2020-12-27T18:00:09+01:00] view original

  I have a project https://github.com/calcit-lang/ternary-tree/blob/master/src/ternary_tree/list.nim#L831 and I wanted to compiled it to js. I tried and figured out I have to add {.exportc.} and then I got this error:

  
  /Users/chen/repo/others/Nim/compiler/nim.nim(119) nim
  /Users/chen/repo/others/Nim/compiler/nim.nim(84) handleCmdLine
  /Users/chen/repo/others/Nim/compiler/main.nim(231) mainCommand
  /Users/chen/repo/others/Nim/compiler/main.nim(204) compileToBackend
  /Users/chen/repo/others/Nim/compiler/main.nim(118) commandCompileToJS
  /Users/chen/repo/others/Nim/compiler/modules.nim(163) compileProject
  /Users/chen/repo/others/Nim/compiler/modules.nim(91) compileModule
  /Users/chen/repo/others/Nim/compiler/passes.nim(202) processModule
  /Users/chen/repo/others/Nim/compiler/passes.nim(73) processTopLevelStmt
  /Users/chen/repo/others/Nim/compiler/jsgen.nim(2667) myProcess
  /Users/chen/repo/others/Nim/compiler/jsgen.nim(2654) genModule
  /Users/chen/repo/others/Nim/compiler/jsgen.nim(2403) genStmt
  /Users/chen/repo/others/Nim/compiler/jsgen.nim(2581) gen
  /Users/chen/repo/others/Nim/compiler/jsgen.nim(1435) genSym
  /Users/chen/repo/others/Nim/compiler/jsgen.nim(1364) genProcForSymIfNeeded
  /Users/chen/repo/others/Nim/compiler/jsgen.nim(2334) genProc
  /Users/chen/repo/others/Nim/lib/system/fatal.nim(49) sysFatal
  Error: unhandled exception: index 7 not in 0 .. 6 [IndexDefect]
  Run

  tried to read source code, not much information...

  then I tried to export a very simple function, it worked.

  proc add*(a, b: int): int {.exportc.} =
    a + 1
  Run

  So I guessed maybe generics is not supported in such a case?

  proc add*[T](a, b: TernaryTreeList[T]): int {.exportc.} =
    3 + 1
  Run

  now I got same error again. So it's really not supported?

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• saem (orginal) [2020-12-27T19:36:21+01:00] view original

  If you try another generic structure like seq, etc... what happens? These errors remind me of ones I've encountered before when working with JS but my memory is fuzzy.

  For JS I've done exports with a JSObject, and that might work better.

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• jrfondren (orginal) [2020-12-27T19:43:01+01:00] view original

  If something's not supported you should expect an error message about your code, not an exception from the guts of the compiler. In this case jsgen.nim#2324 is trying to read outside of an array: resultSym = proc.ast[resultPos].sym where resultPos and proc.ast.len are both 7.

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• jiyinyiyong (orginal) [2020-12-28T11:30:24+01:00] view original

  Code that using seq looks fine.

  proc count*(args: seq[int]): int {.exportc.} =
    return 1
  Run

  I guess add*[T] might be the special case.

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• jiyinyiyong (orginal) [2020-12-28T11:33:58+01:00] view original

  yep.. that's what IndexDefect says.

  I was wondering if that was a not-implemented-yet feature. js is dynamic and hard to say what should such code be compiled to...(not sure whether the author of that commit could see this..)

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