Nim cross compilation to C

The last problem is because you're running gcc for x86_64 arch, while the sources were generated for i386 arch.

I was having the same issue getting nim to compile executables for Windows, from a GNU/Linux machine, so I made a bash script. It takes the path to the directory containing *.nim source files and the name of the executable file to output.

I'm sure you could swap out the GCC compiler (MinGW in this case) and change the --os: switch as appropriate:

#!/usr/bin/env bash
# Nim must generate C sources only, to be fed to MingW
nim c --cpu:amd64 --os:windows --opt:speed --embedsrc --threads:on --checks:on -c -d:release $1/*.nim
# Copy nimbase.h so MingW32 can find it during compilation and linking
cp /opt/Nim/lib/nimbase.h $1/nimcache/nimbase.h
mkdir -p $1/bin
cd $1/nimcache && x86_64-w64-mingw32-gcc -save-temps $1/nimcache/*.c -o $1/bin/$2.exe
rm $1/nimcache/*.{i,s} # only care about *.o objects
ls -lAhF $1/nimcache
ls -lAhF $1/bin