The Windows version might get in trouble with uppercase source filen names. When in trouble try renaming your files. Also avoid program/module names beginning with numbers or symbols.

Multi-dimensional arrays are not supported. They can be emulated in software by partitioning creating a single large array and calculating offsets.

Are supported, but they can't be prototyped, for example:

int (*func)();

is supported, but:

int (*func)(int val, char *str);

is not. This is unfortunate in terms of type safety, but during development you could use something like this to provide type safety:

#ifdef DEVELOPMENT
#define CALLIT(f,v,s)  callmyfunc(f,v,s)
#else
#define CALLIT(f,v,s) f(v,s)
#endif   
 
#ifdef DEVELOPMENT
int callmyfunc(int (*func)(), int val, char *str)
{
   return func(val,str);
}
#endif

Bitfields are not supported.

Expressions are evaluated left to right, and no folding is applied, as a result (1 + j + 3) will generate bulkier code than ( j + 1 + 3 ).

Copying a whole 'struct' node in an array in another position (or another array) won't work, only the first 2 bytes will be moved. This won't work correctly:

  struct segment {
    int x;
    int y;
  } data[10];
  
  data[2].x=6;
  data[2].y=7;
  
  data[1]=data[2];

To solve for small structs, copy the elements one by one.

  data[1].x=data[2].x;
  data[1].y=data[2].y;

For larger structs, it may be more efficient to copy using memcpy().

  memcpy(&data[1], &data[2], sizeof(struct segment));