[Bug target/10964] [3.3/3.4 regression] [i?86] Problem with initialization of reference to pointer

[ehrhardt at mathematik dot uni-ulm dot de]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10964


ehrhardt at mathematik dot uni-ulm dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


------- Additional Comments From ehrhardt at mathematik dot uni-ulm dot de  2003-06-27 12:56 -------
I think this is still not a bug! The problem is with the usage of const.
Here's a reduced version of the source code:

class Bclass
{
protected:
  Bclass( const float * const & p ) {}
};

struct Mclass : public Bclass
{
  Mclass() : Bclass(pointer), pointer (0) { }   /* XXX */
  float *pointer;
};

int main ()
{
        Mclass M;
}

In the line marked with XXX pointer is of type ``float *''. However,
the Bclass constructor expects a ``const float * const'' reference.
These types are NOT reference compatible according to 8.5.3[4] because
of the additional const qualifier. This means according to 8.5.3[5]
that a temporary object is created from the expression ``pointer'' and
the reference in the Bclass constructor is bound to THAT temporary:

	Otherwise, a temporary of type ``cv1 T1'' is created
	and initialized from the initializer expression using
	the rules for a non-reference copy initialization
	(8.5). The reference is then bound to the tem-porary.
	If T1 is reference-related to T2, cv1 must be the same
	cv-qualification as, or greater cv-qualification than,
	cv2; [ ... ]

Consequently the reference is to a temparary, not directly to the
element of Mclass. This explains the two different pointer values.
Due to life time issues (the life time of the reference exceeds that
of the temporary the program is also ill formed.

   regards  Christian