3 ms·

> When compiling and running a C program, the only thing that matters is "what the C abstract machine does". Programs that exhibit UB in the abstract machine ar

> When compiling and running a C program, the only thing that matters is "what the C abstract machine does". Programs that exhibit UB in the abstract machine are allowed to do "anything". This view is alienating systems programmers. You're right that that's what the standard says, but nobody actually wants that except compiler writers trying to juice unrealistic benchmarks. In practice programmers want to alias things, they want to access unaligned memory, they want to cast objects right out of memory without constructing them, etc. And they have real reasons to do so! More narrowly defining how off the rails the compiler is allowed to go, rather than anything is a desirable objective for changing the standard.

tom_ 3y ago
My UB links list is getting on in years, but somehow remains vaguely relevant. "These people simply don't understand what C programmers want": https://groups.google.com/forum/#!msg/boring-crypto/48qa1kWignU/o8GGp2K1DAAJ https://groups.google.com/forum/#!msg/boring-crypto/48qa1kWi... "please don't do this, you're not producing value": http://blog.metaobject.com/2014/04/cc-osmartass.html http://blog.metaobject.com/2014/04/cc-osmartass.html "Everyone is fired": http://web.archive.org/web/20160309163927/http://robertoconcerto.blogspot.com/2010/10/strict-aliasing.html http://web.archive.org/web/20160309163927/http://robertoconc... "No sane compiler writer would ever assume it allowed the compiler to 'do anything' with your code": http://web.archive.org/web/20180525172644/http://article.gmane.org/gmane.os.plan9.general/76989 http://web.archive.org/web/20180525172644/http://article.gma...