On Wed, 2 Nov 2011, DJ Delorie wrote: > > > Index: configure.ac > > > + # Dereferencing -1 is a compile-time error > > > > This (those lines) look a little cryptic (and lack punctuation ;) > > Wild improvement guess: "Too small 'int'?". > > No, the compiler specifically tests for unaligned accesses and gives a > compile-time error, at Renesas's requrest. The chip can't do > unaligned accesses correctly, but it doesn't fault - it just silently > accesses the wrong memory. So the compiler errors instead.
That's not permitted by standard C for code that might not be executed. The standard GCC practice if you can determine at compile time that a given path will result in undefined behavior at runtime but don't want to deduce that this path is unreachable is to generate an abort and output an informative notice with inform (). This is done when float is passed to va_arg, for example, or for calling a function through a function pointer cast to an incompatible type. (I don't see what actually generates the error, since there are only two calls to error () in the port, both of which I've commented on separately.) -- Joseph S. Myers jos...@codesourcery.com
