Richard W.M. Jones wrote: > I think I agree with you. I spent a long time looking at the strict > aliasing warnings generated by GCC for rpcgen-generated code. I > couldn't find a good explanation anywhere for what the problems are > with the code and what sort of bugs the compiler could introduce. For > example, making apparently simple and semantics-preserving changes to > the code made the warning go away, but did that make the bug go away? > (serious question -- I've no idea). In short, you cannot access a variable of type A through a pointer of type B. For example, if x is of type double, it is invalid to use *(int*)&x to get at the double's bits. Some aliasing warnings are also caused by sloppy use of types, e.g. using int instead of long or size_t. (E.g. using int * when the data pointed to is actually of type size_t.) That sort of abuse can also cause breakage on 64-bit platforms, so in those cases the code needs to be fixed to use the correct type anyway. > Does such a reference exist to help us understand the problem? Plenty thereof, see e.g.: http://en.wikipedia.org/wiki/Aliasing_(computing) http://www.cellperformance.com/mike_acton/2006/06/understanding_strict_aliasing.html Searching for "strict aliasing" finds a lot more. Kevin Kofler -- fedora-devel-list mailing list fedora-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-devel-list
