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C and C++ prioritize performance over correctness (2023)

(research.swtch.com)
93 points endorphine | 1 comments | 28 Mar 25 20:26 UTC | HN request time: 0.218s | source
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uecker ◴[31 Mar 25 17:42 UTC] No.43537642[source]▶
You can implement C in completely different ways. For example, I like that signed overflow is UB because it is trivial to catch it, while unsigned wraparound - while defined - leads to extremely difficult to find bugs.
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Strilanc ◴[31 Mar 25 18:23 UTC] No.43538056[source]▶
Could you provide the code you use to trivially catch signed overflows? My impression is the opposite: unsigned is trivial (just test `a+b < b`) while signed is annoying (especially because evaluating a potentially-overflowing expression would cause the UB I'm trying to avoid).
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1. steveklabnik ◴[31 Mar 25 21:04 UTC] No.43539954[source]▶
You're right that this test would be UB for signed integers.

See here for that in action, as well as one way to test it that does work: https://godbolt.org/z/sca6hxer4

If you're on C23, uercker's advice to use these standardized functions is the best, of course.