On Fri, 7 Apr 2017, Florian Weimer wrote: > On 04/06/2017 09:16 PM, Richard Biener wrote: > > On April 6, 2017 8:12:29 PM GMT+02:00, Bernd Edlinger > > <bernd.edlin...@hotmail.de> wrote: > > > But isn't the effective type changed by the assignment b[1] = 0; > > > as described in 6.5(6): > > > "If a value is stored into an object having no declared type through an > > > lvalue having a type that is not a character type, then the type of the > > > lvalue becomes the effective type of the object for that access and for > > > subsequent accesses that do not modify the stored value." > > > > Yes. I think the example is valid. At least GCCs memory model makes it so. > > As far as I understand the standard, C does not permit changing the effective > type of an object if it has a declared type (at least not without a union). > If GCC supports it, that's an undocumented GCC extension.
The GCC middle-end supports it because C++ supports it and there is no way for the C FE to tell the middle-end that this is not valid. Richard.
