On Saturday, 14 March 2015 at 18:26:34 UTC, Robert M. Münch wrote:
Hi, I have a question about how the GC handles this case:
export extern(C) char* foo(){
char[] x = "This is a dynamic D string.".dup;
return(cast(char*)x);
}
Since x is "pointer to array data & length" if it goes out of
scope, it's destroyed and the last reference to the array data
is gone. Hence, the GC could kick in and free the array data.
Is this correct?
Or will the GC know, that there was a pointer to the array data
returned and hence a new reference exists as long until someone
tells the GC that the pointer is no longer used?
My situation is, that the returned pointer is used to copy the
result to some interpreter internal state. Depending on the
answers above, there could be a short time where the memory
state is "collectable" before the coyping was finished.
As long as the pointer remains on the stack or in a register, the
GC will keep the allocation alive. But if your C code stores the
pointer on the C heap or in a global, the GC won't know anything
about it and can free it.
