Am 10.10.2021 um 08:40 schrieb Tom Ivar Helbekkmo: > Roland Illig <ril...@netbsd.org> writes: > >> sh: ignore lint error about 'continue' in 'do while' loop >> >> exec.c(575): error: continue in 'do ... while (0)' loop [323] >> jobs.c(203): error: continue in 'do ... while (0)' loop [323] >> >> It is certainly a rarely used feature, I saw it the first time today >> and I don't see why a 'continue' statement in a 'do while' loop should >> be an error. > > The only reason I can think of for using a 'do ... while (0)' construct > outside of a '#define' is to have a block that's executed once, but that > you can break out of without having to use 'goto'. When you do this, > the keywords 'break' and 'continue' both break out of the block. I > guess what lint is saying here is that because of this, you should use > 'break', and not 'continue', to make it explicit what's happening.
Perfect guess, that's exactly the reason, as stated in https://github.com/NetBSD/src/commit/d4d6980a4bb5db5188b919db from 2008-07-25. At that time, the test suite for lint didn't contain a test for a do-while-0 loop containing a switch statement containing a continue statement, and this case where continue is actually different from break was probably not on the author's mind. I had not looked up the history of the message yesterday since I assumed this error message had been there from the beginning. I should have known the message ID 323 better since that looks really high. Oh well, on a second look it's not that high either since even in 1995 there were already the messages from 0 to 309. Anyway, the code in question was more verbose than necessary, so I made it simpler. I also experimented with replacing the switch with a single if statement, but that would have become too dense and thus difficult to decipher. Roland
