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C++ PATCH: PR 19565

From: Mark Mitchell <mark at codesourcery dot com>
To: gcc-patches at gcc dot gnu dot org
Date: Fri, 14 Oct 2005 12:52:53 -0700
Subject: C++ PATCH: PR 19565
Reply-to: mark at codesourcery dot com
This PR is about missing warnings from the C++ front-end, regarding
overflows when converting integral constants to different types.  I
revised the C++ handling to leverage the functions in c-common.c
designed for this purpose.

I'm not going to apply this to the 4.0 branch because a missed warning
is a very minor problem and this patch does carry some risk.

Tested on x86_64-unknown-linux-gnu, applied on the mainline.

--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
 
2005-10-14  Mark Mitchell  <mark@codesourcery.com>

	PR c++/19565
	* g++.dg/warn/Wconversion1.C: New test.
	* g++.dg/ext/packed4.C: Compile with -w.
	* g++.dg/opt/20050511-1.C: Likewise.
	* g++.old-deja/g++.other/warn4.C: Compiler with -Wconversion.

2005-10-14  Mark Mitchell  <mark@codesourcery.com>

	PR c++/19565
	* g++.dg/warn/Wconversion1.C: New test.
	* g++.dg/ext/packed4.C: Compile with -w.
	* g++.dg/opt/20050511-1.C: Likewise.
	* g++.old-deja/g++.other/warn4.C: Compiler with -Wconversion.

Index: gcc/cp/call.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/call.c,v
retrieving revision 1.558
diff -c -5 -p -r1.558 call.c
*** gcc/cp/call.c	13 Oct 2005 08:38:39 -0000	1.558
--- gcc/cp/call.c	14 Oct 2005 19:43:40 -0000
*************** convert_like_real (conversion *convs, tr
*** 4214,4238 ****
  	    warning (0, "passing %qT for argument %P to %qD",
  		     TREE_TYPE (expr), argnum, fn);
  	  else
  	    warning (0, "converting to %qT from %qT", t, TREE_TYPE (expr));
  	}
-       /* And warn about assigning a negative value to an unsigned
- 	 variable.  */
-       else if (TYPE_UNSIGNED (t) && TREE_CODE (t) != BOOLEAN_TYPE)
- 	{
- 	  if (TREE_CODE (expr) == INTEGER_CST && TREE_NEGATED_INT (expr))
- 	    {
- 	      if (fn)
- 		warning (0, "passing negative value %qE for argument %P to %qD",
- 			 expr, argnum, fn);
- 	      else
- 		warning (0, "converting negative value %qE to %qT", expr, t);
- 	    }
- 
- 	  overflow_warning (expr);
- 	}
      }
  
    switch (convs->kind)
      {
      case ck_user:
--- 4214,4223 ----
*************** convert_like_real (conversion *convs, tr
*** 4428,4439 ****
  			     c_cast_p);
  
      default:
        break;
      }
!   return ocp_convert (totype, expr, CONV_IMPLICIT,
! 		      LOOKUP_NORMAL|LOOKUP_NO_CONVERSION);
  }
  
  /* Build a call to __builtin_trap.  */
  
  static tree
--- 4413,4429 ----
  			     c_cast_p);
  
      default:
        break;
      }
! 
!   if (issue_conversion_warnings)
!     expr = convert_and_check (totype, expr);
!   else
!     expr = convert (totype, expr);
! 
!   return expr;
  }
  
  /* Build a call to __builtin_trap.  */
  
  static tree
Index: gcc/cp/decl.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/decl.c,v
retrieving revision 1.1434
diff -c -5 -p -r1.1434 decl.c
*** gcc/cp/decl.c	13 Oct 2005 23:59:57 -0000	1.1434
--- gcc/cp/decl.c	14 Oct 2005 19:43:41 -0000
*************** finish_enum (tree enumtype)
*** 9748,9757 ****
--- 9748,9759 ----
  	     initializing value.  */
  	  TREE_TYPE (decl) = enumtype;
  
  	  /* Update the minimum and maximum values, if appropriate.  */
  	  value = DECL_INITIAL (decl);
+ 	  if (value == error_mark_node)
+ 	    value = integer_zero_node;
  	  /* Figure out what the minimum and maximum values of the
  	     enumerators are.  */
  	  if (!minnode)
  	    minnode = maxnode = value;
  	  else if (tree_int_cst_lt (maxnode, value))
*************** finish_enum (tree enumtype)
*** 9850,9862 ****
--- 9852,9869 ----
  
    /* Convert each of the enumerators to the type of the underlying
       type of the enumeration.  */
    for (values = TYPE_VALUES (enumtype); values; values = TREE_CHAIN (values))
      {
+       location_t saved_location;
+ 
        decl = TREE_VALUE (values);
+       saved_location = input_location;
+       input_location = DECL_SOURCE_LOCATION (decl);
        value = perform_implicit_conversion (underlying_type,
  					   DECL_INITIAL (decl));
+       input_location = saved_location;
  
        /* Do not clobber shared ints.  */
        value = copy_node (value);
  
        TREE_TYPE (value) = enumtype;
*************** build_enumerator (tree name, tree value,
*** 9942,9952 ****
  				       1, 0, &lo, &hi);
  	      value = build_int_cst_wide (TREE_TYPE (prev_value), lo, hi);
  	      overflowed |= !int_fits_type_p (value, TREE_TYPE (prev_value));
  
  	      if (overflowed)
! 		error ("overflow in enumeration values at %qD", name);
  	    }
  	  else
  	    value = integer_zero_node;
  	}
  
--- 9949,9962 ----
  				       1, 0, &lo, &hi);
  	      value = build_int_cst_wide (TREE_TYPE (prev_value), lo, hi);
  	      overflowed |= !int_fits_type_p (value, TREE_TYPE (prev_value));
  
  	      if (overflowed)
! 		{
! 		  error ("overflow in enumeration values at %qD", name);
! 		  value = error_mark_node;
! 		}
  	    }
  	  else
  	    value = integer_zero_node;
  	}
  
Index: gcc/cp/typeck2.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/typeck2.c,v
retrieving revision 1.192
diff -c -5 -p -r1.192 typeck2.c
*** gcc/cp/typeck2.c	1 Aug 2005 04:02:26 -0000	1.192
--- gcc/cp/typeck2.c	14 Oct 2005 19:43:42 -0000
*************** digest_init (tree type, tree init)
*** 693,706 ****
  	    }
  	  return init;
  	}
      }
  
!   /* Handle scalar types, including conversions,
!      and signature pointers and references.  */
!   if (SCALAR_TYPE_P (type)
!       || code == REFERENCE_TYPE)
      return convert_for_initialization (0, type, init, LOOKUP_NORMAL,
  				       "initialization", NULL_TREE, 0);
  
    /* Come here only for aggregates: records, arrays, unions, complex numbers
       and vectors.  */
--- 693,704 ----
  	    }
  	  return init;
  	}
      }
  
!   /* Handle scalar types (including conversions) and references.  */
!   if (SCALAR_TYPE_P (type) || code == REFERENCE_TYPE)
      return convert_for_initialization (0, type, init, LOOKUP_NORMAL,
  				       "initialization", NULL_TREE, 0);
  
    /* Come here only for aggregates: records, arrays, unions, complex numbers
       and vectors.  */
Index: gcc/testsuite/g++.dg/ext/packed4.C
===================================================================
RCS file: /cvs/gcc/gcc/gcc/testsuite/g++.dg/ext/packed4.C,v
retrieving revision 1.2
diff -c -5 -p -r1.2 packed4.C
*** gcc/testsuite/g++.dg/ext/packed4.C	31 May 2004 21:24:31 -0000	1.2
--- gcc/testsuite/g++.dg/ext/packed4.C	14 Oct 2005 19:43:52 -0000
***************
*** 1,6 ****
--- 1,7 ----
  // { dg-do run }
+ // { dg-options "-w" }
  
  // Copyright (C) 2003 Free Software Foundation, Inc.
  // Contributed by Nathan Sidwell 15 Jul 2003 <nathan@codesourcery.com>
  
  // Packed fields are unsuitable for direct reference binding.
Index: gcc/testsuite/g++.dg/opt/20050511-1.C
===================================================================
RCS file: /cvs/gcc/gcc/gcc/testsuite/g++.dg/opt/20050511-1.C,v
retrieving revision 1.1
diff -c -5 -p -r1.1 20050511-1.C
*** gcc/testsuite/g++.dg/opt/20050511-1.C	18 May 2005 23:54:36 -0000	1.1
--- gcc/testsuite/g++.dg/opt/20050511-1.C	14 Oct 2005 19:43:52 -0000
***************
*** 1,7 ****
  /* { dg-do run } */
! /* { dg-options "-O3" { target powerpc*-*-* } } */
  #include <stdio.h>
  #include <stdlib.h>
  
  typedef signed short SINT16 ;
  typedef unsigned long UINT32 ;
--- 1,8 ----
  /* { dg-do run } */
! /* { dg-options "-w" } */
! /* { dg-options "-O3 -w" { target powerpc*-*-* } } */
  #include <stdio.h>
  #include <stdlib.h>
  
  typedef signed short SINT16 ;
  typedef unsigned long UINT32 ;
Index: gcc/testsuite/g++.dg/warn/Wconversion1.C
===================================================================
RCS file: gcc/testsuite/g++.dg/warn/Wconversion1.C
diff -N gcc/testsuite/g++.dg/warn/Wconversion1.C
*** /dev/null	1 Jan 1970 00:00:00 -0000
--- gcc/testsuite/g++.dg/warn/Wconversion1.C	14 Oct 2005 19:43:56 -0000
***************
*** 0 ****
--- 1,12 ----
+ // { dg-options "-Wconversion" }
+ 
+ char c1 = 1024; // { dg-warning "overflow" }
+ char c2 = char(1024);
+ char c3 = (char) 1024;
+ char c4 = static_cast<char>(1024);
+  
+ unsigned char uc1 = -129; // { dg-warning "unsigned" }
+ 
+ bool b1 = -3;
+ 
+ int i1 = 0x80000000;
Index: gcc/testsuite/g++.old-deja/g++.other/warn4.C
===================================================================
RCS file: /cvs/gcc/gcc/gcc/testsuite/g++.old-deja/g++.other/warn4.C,v
retrieving revision 1.2
diff -c -5 -p -r1.2 warn4.C
*** gcc/testsuite/g++.old-deja/g++.other/warn4.C	1 May 2003 02:02:52 -0000	1.2
--- gcc/testsuite/g++.old-deja/g++.other/warn4.C	14 Oct 2005 19:43:57 -0000
***************
*** 1,6 ****
--- 1,7 ----
  // { dg-do assemble  }
+ // { dg-options "-Wconversion" }
  
  // Copyright (C) 1999 Free Software Foundation, Inc.
  // Contributed by Nathan Sidwell 21 Nov 1999 <nathan@acm.org>
  
  // make sure we only warn on assigning a negative (signed) value
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