C/C++ FEs: Do we really need three char_type_nodes?

[Jason Merrill]

Mark Mitchell wrote:
> Is that desirable?  Type-based alias analysis should be able to take
> advantage of the difference between them; a "char **" and a "signed char
> **" cannot point at the same thing, for example.

They can.  In C++, a char* (or unsigned char*) can alias anything, and 
any signed/unsigned type can alias the other signage.

Jason