invoking nim procedures from C do not trap unhandled exceptions.

[planetis-m]

The following is the modified example from https://nim-lang.github.io/Nim/backends.html#interfacing-backend-code-calling-nim test with and without --gc:arc to see the difference.

Example

fib.nim

proc testOneInput: cint {.exportc.} =
  if true:
    raise newException(ValueError, "my my my")

proc customMutator(): int {.exportc.} =
  try:
    discard
  except:
    echo "customMutator"
    quit(1)

maths.c

#include "fib.h"
#include <stdio.h>

int main(void)
{
  NimMain();
  testOneInput();
  // the following should not be called
  customMutator();
  return 0;
}

Current Output

with --gc:arc

customMutator

Expected Output

without

Error: unhandled exception: my my my [ValueError]

Possible Solution

Something to do with nimTestErrorFlag() not being called.

$ nim -v
1.5.1