> Which part of the program do you believe violates the restrict promise?
The part where they modify a piece of memory using `x` and then modify the same piece using `y`.
That's a promise the programmer made inside that function and for anyone else who calls the function. This is C, so it's not the compiler's job to prove the implementer or caller got it right.
I see your point, but this is really niddly. It explicitly asks if the address in `x` is equal to the address in `y-1`. And if so, it modifies the contents at that address which is equal to both.
If the conclusion was that the C standard could/should tighten up its verbiage for cases like this, I'd agree. But the conclusion is something about adding provenance to integers...
The part where they modify a piece of memory using `x` and then modify the same piece using `y`.
That's a promise the programmer made inside that function and for anyone else who calls the function. This is C, so it's not the compiler's job to prove the implementer or caller got it right.