How about allowing `return` to be used as a qualifier within a function or prototype's argument which, if present, would adjust the qualifiers of the function's return value to match those of the argument, e.g. adding "const" or removing "volatile" as appropriate?

This, if one did:

    char *strchr2(char return *restrict src, char target)
    {
      while(*src)
      {
        if (*src == target) return src;
        src++;
      }
    }

then one version of the function could support both const and non-const usage. BTW, I'd also like to see "register" and "return register" be usable as a qualifiers for pointer-type function parameters which would promise that the passed in pointer wouldn't "escape", or else that it could only escape through the return value (so a compiler that could see everything done with the return value wouldn't have to worry about the argument escaping).