Rustaceans at the border [LWN.net]

Rustaceans at the border

Posted Apr 17, 2022 22:10 UTC (Sun) by bartoc (guest, #124262)
In reply to: Rustaceans at the border by khim
Parent article: Rustaceans at the border

Rust “UB” is a smaller category than c/c++ because theres no formal standard for the language with multiple implementers. Not all ub in C is assumed to never happen by compilers (for ex: most of the preprocessor and lexer UB)

The other thing to remember is that the C standard can be obscenely vague about what implementations are allowed to do, the C++ standard tries much harder.

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Rustaceans at the border

Posted Apr 19, 2022 15:44 UTC (Tue) by tialaramex (subscriber, #21167) [Link]

> Rust “UB” is a smaller category than c/c++ because theres no formal standard for the language with multiple implementers.

It's not about multiple implementations, at most that would lead to having Implementation Defined Behaviour which is much less scary, but in many cases there wouldn't be any difference since the additional implementations would just do the same thing.

C++ in particular is riddled with _intentional_ Undefined Behaviour. But even in the mundane C standard library trivial functions like abs() have Undefined Behaviour.