On Sat, Aug 30, 2008 at 8:08 AM, Marc Lehmann <[EMAIL PROTECTED]> wrote: > On Fri, Aug 29, 2008 at 05:11:23PM +0200, Egon Eckert <[EMAIL PROTECTED]> > wrote: >> sorry about introducing the ever-appearing aliasing-warnings theme :)... Can >> someone, please, explain why *not* doing the cast in following macro >> definition: > > not doing the cast accesses the "at" member of *ev (with unknown type, but > usually the type isn't ev_watcher_time), doing the cast accesses the at > member of the ev_watcher_time struct overlaying whatever ev's real type > is. > > since all the remaining code also accesses the ev_watcher_time.at, leaving > out the cast allows the compiler to reorder code because can assume they > are not the same lvalues. (in practise, this doesn't happen between source > files yet, but it does happen within the same source file). > > In c++, one could use an explicit static cast to typecheck, but not in C. > (in c++, of course, one could simply subclass...)
I'm have this issue too, compiling my project with -Werror -Wall -W (by policy) ev_timer_set(&self->timeout, 0.0, timeout); (same with _init) with self.timeout been a "struct ev_timer" leads to warning: dereferencing type-punned pointer will break strict-aliasing rules and compiling stops.. but (&self->timeout)->at = 0.0; (&self->timeout)->repeat = (timeout); without the cast, compiles flawlessly. there is any decent way to solve this? Thanks, Alejandro Mery _______________________________________________ libev mailing list libev@lists.schmorp.de http://lists.schmorp.de/cgi-bin/mailman/listinfo/libev
