>From [Nim Compiler user
>guide](https://nim-lang.org/docs/nimc.html#dll-generation):
Nim supports the generation of DLLs. However, there must be only one
instance of the GC per process/address
space. This instance is contained in nimrtl.dll. This means that every
generated Nim DLL depends on
nimrtl.dll.
To generate the "nimrtl.dll" file, goto Nim/lib directory and use the command:
nim c -d:release nimrtl.nim
then compile your project with:
nim --app:lib -d:useNimRtl c lib
nim c -d:useNimRtl main
nimRtl not used if there is only single instance of GC, such as C app + Nim
DLL, or Nim app + C dll. nimRtl used in situation like Nim app + Nim DLL, or C
app + multiple Nim DLL
