Ziemowit Laski writes:

> Indeed, I now appear to have a mainline mod for C and C++ which allows 
> assignment to lvalue casts for pointer types.  What follows is a 
> high-level synopsis of what I did; if there is interest, I can whip up 
> a full-fledged patch, complete with docs.  Please let me know.

It occurs to me -- can't "lvalue casts" be done in standard GNU C and C++?
Source code changes would be required, but they can probably be done largely
mechanically.

Here are the examples I've got -- they can maybe be cleaned up a bit, but
both of these compile your test cases -Wall-cleanly with GCC 3.4.  (They
take advantage of the GCC extension that type-punning through a union is
defined behavior.)

First, the C++ example, since it's cleaner code: