Throwing exceptions in methods declared __attribute__((pure)) leads to abort on (at least) FreeBSD

[musicplayerdaemon]

Throwing exceptions in methods declared __attribute__((pure)) leads to abort on (at least) FreeBSD

[ephemeralriggs]

Wow, this is interesting! You mean like setting
#define gcc_pure
in Compiler.h?
Does this happen to solve the library update problem mentioned in https://forum.musicpd.org/viewtopic.php?f=7&t=4318#p6880 and https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=219048 ?
Will test this ...

[ephemeralriggs]

Seems indeed to work!
Thanks for tracking down this one!

[jonsiddle]

Yes, that's exactly what I did. I didn't bother with a patch since it was such a simple change and I figured someone who knew the code might want to do it properly and keep the optimisation where exceptions weren't used or make it based on compiler. I'd be happy to have a go at a better fix if that would be helpful.

[MaxKellermann]

Huh, interesting find. The GCC documentation of pure leaves this part undefined - it does not mention whether "pure" functions are allowed to throw exceptions (which I interpreted as just another kind of "return value"), while clang appears to assume that a pure function is also noexcept.

[MaxKellermann]

I quickly wrote a clang plugin which shows me code locations that need to be fixed: https://gist.github.com/MaxKellermann/758ed94d66cc744fe163bee0f854352d

[jonsiddle]

Nice way to find them. I've applied the commit and can confirm it fixes the issue I was seeing.