Global objects are not freed with noMain

[planetis-m]

Similar issue to #18215 but in regards to global objects

Example

type
  Foo = ref object
    data: string

var
  f = Foo(data: newStringOfCap(1000))

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

int main(void)
{
  NimMain();
  return 0;
}

Compile with:

nim c --cc:clang --noMain --noLinking --header:fib.h -d:danger --gc:arc -d:usemalloc --panics:on -d:nosignalhandler fib.nim
clang -o m -I$HOME/.cache/nim/fib_r -Ipath/to/Nim/lib $HOME/.cache/nim/fib_r/*.c -fsanitize=leak maths.c

Btw I can't make leak sanitizer to detect this (even with -d:useMalloc), but it seems pretty obvious that global resources acquired in NimMain are never freed.

Possible Solution

Should there be a NimExit proc to be called manually at the end that handles destructions, unhandled exceptions... ?

$ nim -v
Nim Compiler Version 1.5.1 [Linux: amd64]
Compiled at 2021-06-14
Copyright (c) 2006-2021 by Andreas Rumpf

git hash: 2d34b1f5bc45a180d1b53d6c24857133859a4f46
active boot switches: -d:release --gc:markAndSweep