[c++] conditional expr abort

[Richard Henderson <rth at redhat dot com>]

The following test case fails on (afaik) all versions:

extern int a1[];
extern int a2[];
void foo(int p)
{
  int x = (p ? a1 : a2)[1];
}

/home/rth/zz.cc: In function `void foo(int)':
/home/rth/zz.cc:5: Internal compiler error in assign_stack_temp_for_type, at
   function.c:663

After two attempts that created more problems than it solved
due to utterly strange c++ rules, I came up with the following
that did pass the test suite.  Ok?


r~


	* call.c (build_conditional_expr): Decompose same_type_p array
	lvalues around the COND_EXPR.

Index: call.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/call.c,v
retrieving revision 1.265
diff -c -p -d -r1.265 call.c
*** call.c	2001/03/23 01:49:10	1.265
--- call.c	2001/04/08 19:32:06
*************** build_conditional_expr (arg1, arg2, arg3
*** 3001,3010 ****
  
       If the second and third operands are lvalues and have the same
       type, the result is of that type and is an lvalue.  */
!   if (real_lvalue_p (arg2) && real_lvalue_p (arg3) && 
!       same_type_p (arg2_type, arg3_type))
      {
        result_type = arg2_type;
        goto valid_operands;
      }
  
--- 3001,3023 ----
  
       If the second and third operands are lvalues and have the same
       type, the result is of that type and is an lvalue.  */
!   if (real_lvalue_p (arg2) && real_lvalue_p (arg3)
!       && same_type_p (arg2_type, arg3_type))
      {
        result_type = arg2_type;
+ 
+       /* ??? We can get into trouble with assign_stack_temp_for_type
+ 	 vs incomplete arrays.  Since C++ does not allow us to decay
+ 	 the type here, play games.  */
+       if (TREE_CODE (arg2_type) == ARRAY_TYPE)
+ 	{
+ 	  arg2 = decay_conversion (arg2);
+ 	  arg3 = decay_conversion (arg3);
+ 	  result = fold (build (COND_EXPR, TREE_TYPE (arg2), arg1, arg2, arg3));
+ 	  result = fold (build1 (INDIRECT_REF, result_type, result));
+ 	  return result;
+ 	}
+ 
        goto valid_operands;
      }