Not allowing a cast from integer to pointer is the point of having pointers as capabilities in the first place.
Central in that idea of capabilities is that you can only narrow privileges, never widen them. An intptr_t would in-effect be a capability narrowed to be used only for hashing and comparison, with the right for reading and writing through it stripped away.
BTW, if you would store the uintptr_t then it would lose its notion of being a pointer, and Fil-C's garbage collector would not be able to trace it.
The C standard allows casts both ways, but the [u]intptr_t types are optional. However, C on hardware capability architectures' (CHERI, Elbrus, I dunno about AS/400) tend to make the type available anyway because the one-way cast is so common in real-world code.
#include <stdio.h>
int main()
{
const char c[] = "Howling\n";
char *p = (char*)c;
p[4] = 'o';
printf("%s", c);
return 0;
}
Same results with Debian clang (and clang++) version 14.0.6 with the same options.
Of course, if you change c[] to *c, it will segfault. But it still compiles successfully without warnings.
Laundering your pointer through an integer is evidently not necessary.
But if you try to write to a readonly global constant then you’ll panic. And there are a handful of ways to allocate readonly data via Fil-C’s APIs.
And now I have confused faces looking at me why I just laughed out loud.
Ok that got a chuckle out of me haha
No one person could write a compiler for it, and even if they could they would forget as much in doing so as they could learn.
If the laundering through integers is syntactically obvious - obvious that the cast back from int used a int that obviously can from a pointer - then I allow it.