If a particular compiler specified that casting pointers of wrong alignments causes a segfault, it'd be perfectly acceptable to rely on that behavior. The standard would consider it UB, but that compiler has defined that behavior sufficiently.
Note, though, that a compiler simply doing a particular thing now isn't good enough to specify it in the sense that I mean. The compiler writers would have to explain (in a blog post or the like) the behavior and that they plan to keep that behavior in all future versions.
Note, though, that a compiler simply doing a particular thing now isn't good enough to specify it in the sense that I mean. The compiler writers would have to explain (in a blog post or the like) the behavior and that they plan to keep that behavior in all future versions.