On Sat, Nov 12, 2005 at 10:47:33AM -0800, Per Bothner wrote: > Per Bothner wrote: > >A "function-never-returns-null" attribute doesn't seem like > >the right mechanism. Instead, there should be a "never-null" > >attribute on pointer types. A "function-never-returns-null" is > >just a function whose return-type has the "never-null" attribute. > > Gabriel Does Reis wrote: > >We already have such mechanism: a reference type -- which morally is > >implemented as a pointer type. > > Andrew Pinski wrote: > >That was mentioned a way ago as being wrong. A reference type can be NULL. > > There are other differences, at least in C++: If you assign to a > pointer, you change the pointer, while if you assign to a reference > you modify the referenced object. I.e. if a variable has reference > type, then the reference itself is constant.
That's two separate features: the first is about how the source code is interpreted (and that corresponds to informing the debugger that the object is auto-dereferenced). The second corresponds to declaring that a pointer is itself const. So a C++ reference could be represented as a middle-end pointer type, provided that it is marked as auto-dereferencing, never null, and constant.
