On Mon, 1 Sep 2025 17:19:52 +0200 Philipp Klaus Krause <p...@spth.de> wrote:
> void *realloc(void *ptr, size-t size); > > C90: "[…] If the space cannot be allocated, the object pointed to by ptr > is unchanged. If size is zero and ptr is not a null pointer, the object > it points to is freed." > > C99TC2 (also C99TC3 and C11): "[…] If memory for the new object cannot > be allocated, the old object is not deallocated and its value is unchanged." > > C17: "If size is zero and memory for the new object is not allocated, it > is implementation-defined whether the old object is deallocated. If the > old object is not deallocated, its value shall be unchanged." > > C23 (same in current C2Y draft): "[…] if the size is zero, the behavior > is undefined. If memory for the new object is not allocated, the old > object is not deallocated and its value is unchanged." > > Currently, our malloc and realloc cannot allocate an object of size > zero, they return NULL on such a request, and realloc does free. To me > that looks compliant with C90, C17 and C23, but not C99. > > I would like to change that to allowing allocation of zero-sized objects > instead. Then, malloc(0) and realloc(ptr, 0) would return a non-null > pointer. This would be compliant with C99, C17 and C23, but not C90. I would disagree with your interpretation re C90. It's possible to allocate zero bytes, it's just metadata tracking space that is allocated but it's not an impossible act. So I believe you are compliant with C90 anyway. They just made it more explicit. Classic Unix returned a pointer for zero sized allocations and realloc. Alan _______________________________________________ Sdcc-user mailing list Sdcc-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sdcc-user
