Animation: Silence false positive -Wstringop-overflow warning

[akien-mga]

And disable debug code which was wrongly left enabled.

@marxin I don't know if that's an expected false positive from GCC, or a situation which is still risky enough (while being correct in this case) to warrant warning just in case. I reduced it to this:

#include <cstdint>
#include <cstdio>

uint32_t some_func(const uint32_t components) {
	uint8_t header[8];
	uint32_t header_bytes = 0;
	for (uint32_t i = 0; i < components; i++) {
		header_bytes += 2;
	}
	header_bytes += 2;
	// This works it around, but shouldn't be needed AFAICT.
	//while (header_bytes != 8 && header_bytes % 4 != 0) {
	while (header_bytes % 4 != 0) {
		header[header_bytes++] = 0;
	}
	for (uint32_t i = 0; i < header_bytes; i++) {
		printf("%d\n", header[i]);
	}
	return header_bytes;
}

int main() {
	some_func(1);
	some_func(3);
	return 0;
}

$ g++ main.cpp -O3 -Wstringop-overflow=2
main.cpp: In function ‘uint32_t some_func(uint32_t)’:
main.cpp:14:40: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
   14 |                 header[header_bytes++] = 0;
      |                 ~~~~~~~~~~~~~~~~~~~~~~~^~~
main.cpp:5:17: note: at offset 8 into destination object ‘header’ of size 8
    5 |         uint8_t header[8];
      |                 ^~~~~~

It doesn't happen with lower levels of optimization (and happens with any level of -Wstringop-overflow=).

[marxin]

I've just reported the false positive here:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104789

Note the warning has non-zero false positive rate :P

[marxin]

@akien-mga: Can you please reply to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104789#c3 ?

[akien-mga]

@akien-mga: Can you please reply to gcc.gnu.org/bugzilla/show_bug.cgi?id=104789#c3 ?

I'm not familiar with the term "bounded roo". I reduced the test case as much as I could to focus on the minimal code that would trigger the warning which seems to me like a false positive - is it not one?

I can try to include all the relevant code to do marshalling but it seems to me that it will just make the test case more complex - while the minimal one does reproduce an issue with the same symptoms.

[marxin]

All right, so please reply it to the GCC bug.