[Bug c++/37146] [4.4 Regression] Invalid types with COND_EXPR

["mmitchel at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #13 from mmitchel at gcc dot gnu dot org  2008-09-23 18:38 -------
The C++ WP draft I have (a bit old) says:

If the second and third operands are lvalues and have the same type, the result
is of that type and is an lvalue and it is a bit-field if the second or the
third operand is a bit-field, or if both are bit-fields.

So, I don't see why:

> (x ? c.i : a) = y; should not be valid 

In C++, "type" does not include the number of bits in the bit-field.  

I think think the expression "x ? c.i : a" is an lvalue bit-field of type
"int".

On that basis, I think the gimplifier (including C++-specific hooks thereto)
should handle converting down to whatever representation GENERIC requires.  

I'd expect something like:

  t = SAVE_EXPR (y), 
   x ? (c.i = (int-of-N-bits) t) : (a = t), 
   t

We could also do this in the FE proper (before GENERIC) if required; we would
fix up the conditional expression after working out whether it's being used as
an lvalue or an rvalue.


-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mmitchel at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37146