Program that using OpenMP crashes with segfault without -d:release flag

[Widowan]

I tried to compile OpenMP 
[example](https://rosettacode.org/wiki/Concurrent_computing#Nim) from 
RosettaCode but it just fails with segfault. After playing with it a bit i 
found out that it compiles perfectly normal with -d:release flag, i.e.: 
    
    
    $ nim --passC:-fopenmp --passL:-fopenmp c main 1>/dev/null 2>&1 && ./main
    Enjoy
    Segmentation fault
    
    
    Run

With flag: 
    
    
    $ nim -d:release --passC:-fopenmp --passL:-fopenmp c main 1>/dev/null 2>&1 
&& ./main
    Rosetta
    Code
    Enjoy
    
    
    Run

Is this a bug or I am missing something?