[GCC-3.3.4] Fix for C++/14802

[Gabriel Dos Reis]

This is a backport from part of Mark's

  http://gcc.gnu.org/ml/gcc-patches/2004-03/msg01568.html

to fix PR C++/14082.  The audit trail of that PR contains also a
proposed patch which is identical to Mark's. 

Bootstrapped and regtested on an i686-pc-linux-gnu.

-- Gaby

Index: cp/ChangeLog
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/ChangeLog,v
retrieving revision 1.3076.2.269
diff -p -r1.3076.2.269 ChangeLog
*** cp/ChangeLog	8 May 2004 21:52:42 -0000	1.3076.2.269
--- cp/ChangeLog	16 May 2004 22:49:57 -0000
***************
*** 1,3 ****
--- 1,11 ----
+ 2004-05-16  Gabriel Dos Reis  <gdr@integrable-solutions.net>
+ 
+ 	Backport from mainline:
+ 	2004-03-18  Mark Mitchell  <mark@codesourcery.com>
+ 	* call.c (build_conditional_expr): Do not call force_rvalue for
+ 	operands of void_type when the conditional expression itself has
+ 	void type.
+ 
  2004-05-08  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
  
  	* Make-lang.in (cp/init.o): Depend on diagnostic.h.
Index: cp/call.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/call.c,v
retrieving revision 1.341.2.41
diff -p -r1.341.2.41 call.c
*** cp/call.c	13 Mar 2004 02:00:56 -0000	1.341.2.41
--- cp/call.c	16 May 2004 22:50:00 -0000
*************** build_conditional_expr (arg1, arg2, arg3
*** 3242,3259 ****
  	   type of the other and is an rvalue.
  
  	 --Both the second and the third operands have type void; the
! 	   result is of type void and is an rvalue.  */
        if (TREE_CODE (arg2) == THROW_EXPR 
  	  && TREE_CODE (arg3) != THROW_EXPR)
  	{
! 	  arg3 = force_rvalue (arg3);
  	  arg3_type = TREE_TYPE (arg3);
  	  result_type = arg3_type;
  	}
        else if (TREE_CODE (arg2) != THROW_EXPR 
  	       && TREE_CODE (arg3) == THROW_EXPR)
  	{
! 	  arg2 = force_rvalue (arg2);
  	  arg2_type = TREE_TYPE (arg2);
  	  result_type = arg2_type;
  	}
--- 3242,3265 ----
  	   type of the other and is an rvalue.
  
  	 --Both the second and the third operands have type void; the
! 	   result is of type void and is an rvalue.  
! 
!          We must avoid calling force_rvalue for expressions of type
! 	 "void" because it will complain that their value is being
! 	 used.   */
        if (TREE_CODE (arg2) == THROW_EXPR 
  	  && TREE_CODE (arg3) != THROW_EXPR)
  	{
! 	  if (!VOID_TYPE_P (arg3_type))
! 	    arg3 = force_rvalue (arg3);
  	  arg3_type = TREE_TYPE (arg3);
  	  result_type = arg3_type;
  	}
        else if (TREE_CODE (arg2) != THROW_EXPR 
  	       && TREE_CODE (arg3) == THROW_EXPR)
  	{
! 	  if (!VOID_TYPE_P (arg2_type))
! 	    arg2 = force_rvalue (arg2);
  	  arg2_type = TREE_TYPE (arg2);
  	  result_type = arg2_type;
  	}
Index: testsuite/g++.dg/expr/cond5.C
===================================================================
RCS file: testsuite/g++.dg/expr/cond5.C
diff -N testsuite/g++.dg/expr/cond5.C
*** /dev/null	1 Jan 1970 00:00:00 -0000
--- testsuite/g++.dg/expr/cond5.C	16 May 2004 22:50:01 -0000
***************
*** 0 ****
--- 1,3 ----
+ void f() {
+   true ? throw 1 : (void)7;
+ }