I'm actually pretty impressed how this bug was not caught before. The compiler warning is just one thing that came to my mind but test coverage should have been the strongest hint. A linter could have also make the thing easier for a code review. Probably these parts of the code should have stricter coding guideline.
Not by default. On both GCC and Clang this kind of error isn't caught using -Wall or even -Wextra - you have to explicitly opt-in using -Wunreachable-code. It'd really be nice if that changed and Clang basically had close to -Weverything on by default and required you to opt out, preferably with something like `#pragma ALLOW_SHODDY_<category>` per file to put some pressure on C programmers not to just continue ignoring errors rather than fixing them.
Either way, definitely avoidable.
Looks typical of a merge cock up to me as the indentation is preserved suggesting it's a duplicate line or there was an if statement on the previous line that was removed.
> However later code is used as a jump target for goto so it's quite hard for the compiler to infer this
Nope, because a jump target always starts a new basic block.