c++: Wrong error with alias template in class tmpl [PR104108]

c++: Wrong error with alias template in class tmpl [PR104108]

In r10-6329 I tried to optimize the number of calls to v_d_e_p in
convert_nontype_argument by remembering whether the expression was
value-dependent in a bool flag.  I did that wrongly assuming that its
value-dependence will not be changed by build_converted_constant_expr.
This testcase shows that it can: b_c_c_e gets a VAR_DECL for m_parameter,
which is not value-dependent, but we're converting it to "const int &"
so it returns

  (const int &)(const int *) &m_parameter

which suddenly becomes value-dependent because of the added ADDR_EXPR:
has_value_dependent_address is now true because m_parameter's context S<T>
is dependent.  With this bug in place, we went to the second branch here:

      if (TYPE_REF_OBJ_P (TREE_TYPE (expr)) && val_dep_p)
        /* OK, dependent reference.  We don't want to ask whether a DECL is
           itself value-dependent, since what we want here is its address.  */;
      else
        {
          expr = build_address (expr);

          if (invalid_tparm_referent_p (type, expr, complain))
            return NULL_TREE;
        }

wherein build_address created a bad tree and then i_t_r_p complained.

	PR c++/104108

gcc/cp/ChangeLog:

	* pt.cc (convert_nontype_argument): Recompute
	value_dependent_expression_p after build_converted_constant_expr.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/alias-decl-74.C: New test.