gmpxx implicit conversion between types

[Torbjorn Granlund]

Marc Glisse <marc.glisse at inria.fr> writes:

  There is 0 effect on libgmpxx. Yes, it only affects source
  compatibility. Some (very questionable) code will stop
  compiling. Other than that, I don't think it can break anything, even
  if linking together .o files from before and after the change.

Ok, should we allow any implicit conversions between GMP types?  I think
C's type conversions are actively harmful, but C++ has done some cleanup
in this area with which I am only vaguely.

When dealing with "heavy" types like these, is it in the C++ spirit to
allow implicit conversions?  Will we do any good by disallowing them?

-- 
Torbjörn