Enable more sanitizers in make develop

[Rangi42]

• -fsanitize=undefined encompasses multiple checks we were specifying
• "detect_leaks=1" for __asan_default_options checks for memory leaks (except for with macOS clang++, which does not support LSan)
• -fsanitize=float-divide-by-zero is an extra UBSan check (and reveals a UB bug to fix with fixed-point DIV and LOG)

[Rangi42]

clang: error: unsupported option '-fsanitize=leak' for target 'arm64-apple-darwin23.6.0'

Hmm. Does BSD make have a way to not pass this flag for that compiler? (Or we can just start using gmake... 🥺)

[Rangi42]

Actually, can't we just leave out -fsanitize=leak entirely? Because -fsanitize=address already checks for memory leaks (at least if we pass ASAN_OPTIONS=detect_leaks=1), as well as more things like OOB writes.

[Rangi42]

-fsanitize=undefined enables "All of the checks listed above other than float-divide-by-zero, unsigned-integer-overflow, implicit-conversion, local-bounds and the nullability-* group of checks." I've enabled float-divide-by-zero, local-bounds, and nullability, but not unsigned-integer-overflow or implicit-conversion because those are technically defined behavior and I'm not sure if we actually rely on them or not.

Edit: never mind:

g++: error: unrecognized argument to ‘-fsanitize=’ option: ‘local-bounds’
g++: error: unrecognized argument to ‘-fsanitize=’ option: ‘nullability’

Edit 2: g+ would also not support unsigned-integer-overflow or implicit-conversion, so they're moot anyway.

Edit 3: Also, I was right, we do rely on them. When I locally build make CXX=clang++ develop and ran the asm tests, -fsanitize=unsigned-integer-overflow and -fsanitize=implicit-conversion complained about a lot of things. They're both well-defined behaviors, so there's no real need for us to check for them, even though those checks exist for "suspicious behavior". ("Issues caught by these sanitizers are not undefined behavior, but are often unintentional.")

[Rangi42]

@ISSOtm We have no good solution for conditionally enabling flags based on the OS/compiler in the Makefile, because we're committed to supporting the super-limited BSD/POSIX make. However, it's trivial in cmake. Given that enabling -fsanitize=float-divide-by-zero already just caught a UB issue, I'd quite like to enable more of the checks that -fsanitize=undefined doesn't cover, on the platforms that support those checks. Would it be acceptable for the cmake build to potentially check more things than the make build does?

Resolved

[ISSOtm]

Seems good! Thank you.