Re: So You Think You Can Const?

On 08/01/2025 17:48, Andrey Tarasevich wrote:

 It is perfectly safe. One can even argue that standard declaration if `free` as `void free(void *)` is defective. It should have been `void free(const void *)` from the very beginning.
 

It is common in simple heap implementations for the allocated block to contain data about the block, such as allocation sizes and pointers to other blocks, in memory just below the address returned by malloc. free() then uses its parameter to access that data, and may change it. So "void free(const void *);" would be lying to the user.
Even without that, since you are now giving away the memory for re-use by other code, it's reasonable to say that "free" might change the data pointed to.  (And a security-paranoid "free" might zero out the memory before returning it to the heap for re-use.)