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7356 :: Bug? Compiled code throws some C-lang error.

• alexeypetrushin (orginal) [2021-01-08T21:01:23+01:00] view original

  Code below throws C-lang error, seems like a bug?

  The example is a broken (to make example simpler) implementation of the argmin function.

  playground

  import sugar, sequtils
  
  func findi_min*[T](list: openarray[T], op: (T) -> float): int =
    list.map((v) => (op(v), 0))[0][1]
  
  proc find_something(v: int, list: seq[int]): int =
    list.findi_min((r) => (r - v).abs)
  
  echo find_something(1, @[1])
  Run

  
  Hint: used config file '/playground/nim/config/nim.cfg' [Conf]
  Hint: used config file '/playground/nim/config/config.nims' [Conf]
  .........
  Hint: gcc -c  -w -fmax-errors=3   -I/playground/nim/lib -I/usercode -o /usercode/nimcache/stdlib_io.nim.c.o /usercode/nimcache/stdlib_io.nim.c [Exec]
  Hint: gcc -c  -w -fmax-errors=3   -I/playground/nim/lib -I/usercode -o /usercode/nimcache/stdlib_system.nim.c.o /usercode/nimcache/stdlib_system.nim.c [Exec]
  Hint: gcc -c  -w -fmax-errors=3   -I/playground/nim/lib -I/usercode -o /usercode/nimcache/stdlib_sequtils.nim.c.o /usercode/nimcache/stdlib_sequtils.nim.c [Exec]
  Hint: gcc -c  -w -fmax-errors=3   -I/playground/nim/lib -I/usercode -o /usercode/nimcache/@min.nim.c.o /usercode/nimcache/@min.nim.c [Exec]
  /usercode/nimcache/@min.nim.c: In function 'find_something__Sy1A5qO72g9aM0AG1s9c03Iw':
  /usercode/nimcache/@min.nim.c:551:86: error: incompatible type for argument 3 of 'findi_min__21HJ9aws2bHQ5Ulk4MVcpCQ'
    result = findi_min__21HJ9aws2bHQ5Ulk4MVcpCQ(list->data, (list ? list->Sup.len : 0), T1_);
                                                                                        ^~~
  In file included from /usercode/nimcache/@min.nim.c:11:0:
  /usercode/nimcache/@min.nim.c:498:29: note: expected 'tyProc__1un7Zt9bB5WVQaIdXFZeiNQ {aka struct <anonymous>}' but argument is of type 'tyProc__vwnqUR9cTZ8xwFKGcxd2hkw {aka struct <anonymous>}'
   N_LIB_PRIVATE N_NIMCALL(NI, findi_min__21HJ9aws2bHQ5Ulk4MVcpCQ)(NI* list, NI listLen_0, tyProc__1un7Zt9bB5WVQaIdXFZeiNQ op) {
                               ^
  /playground/nim/lib/nimbase.h:252:44: note: in definition of macro 'N_NIMCALL'
   #  define N_NIMCALL(rettype, name) rettype name /* no modifier */
                                              ^~~~
  Error: execution of an external program failed: 'gcc -c  -w -fmax-errors=3   -I/playground/nim/lib -I/usercode -o /usercode/nimcache/@min.nim.c.o /usercode/nimcache/@min.nim.c'
  Run

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• haxscramper_ (orginal) [2021-01-08T21:11:38+01:00] view original

  It seems like one, because replacing (r) => (r - v).abs with proc(r: int): float = float abs(r - v) solves the issue.

  My guess that it is related to proc signature inference - you require T -> float, but r => abs(r - v) by itself is int -> int, but your proc expects int -> float

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• alexeypetrushin (orginal) [2021-01-08T21:18:47+01:00] view original

  Thanks, seems like the code below is also a bug, as it compiles and runs, but it shouldn't.

  As there's an error - the return of the (r) => (r - 1) expression is int, but the findi_min expect a proc with the float as return type, seems like it shouldn't compile...

  import sugar, sequtils
  
  func findi_min*[T](list: openarray[T], op: (T) -> float): int =
    0
  
  echo @[1].findi_min((r) => (r - 1))
  Run

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