Re: c/10604: -Wall includes sign conversion warning [3.3 regression]

[Zack Weinberg <zack@codesourcery.com>]

The following reply was made to PR c/10604; it has been noted by GNATS.

From: Zack Weinberg <zack@codesourcery.com>
To: ak@suse.de
Cc: gcc-gnats@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: Re: c/10604: -Wall includes sign conversion warning [3.3
 regression]
Date: Fri, 02 May 2003 13:47:13 -0700

 It looks like this was experimentally changed as part of the C
 option-parsing rewrite; since it clearly causes problems, it should be
 put back the way it was.  I am testing the appended patch; Mark has
 approved it for 3.3 if it works.  (The patch for 3.4 will be slightly
 more invasive, because I'm going to get rid of a historical wart at
 the same time; that will come later.)
 
 zw
 
         PR c/10604
         * c-opts.c (c_common_decode_option <OPT_Wall>): Set
         warn_sign_compare for C++ only.
         * doc/invoke.texi: Clarify documentation of -Wsign-compare.
         * gcc.dg/compare7.c, g++.dg/warn/compare1.C: New testcases.
 
 ===================================================================
 Index: c-opts.c
 --- c-opts.c	21 Feb 2003 06:12:58 -0000	1.24.6.1
 +++ c-opts.c	2 May 2003 20:38:22 -0000
 @@ -699,7 +699,8 @@ c_common_decode_option (argc, argv)
        warn_parentheses = on;
        warn_return_type = on;
        warn_sequence_point = on;	/* Was C only.  */
 -      warn_sign_compare = on;	/* Was C++ only.  */
 +      if (c_language == clk_cplusplus)
 +	warn_sign_compare = on;
        warn_switch = on;
        warn_strict_aliasing = on;
        
 ===================================================================
 Index: doc/invoke.texi
 --- doc/invoke.texi	23 Apr 2003 21:45:32 -0000	1.209.2.26
 +++ doc/invoke.texi	2 May 2003 20:44:55 -0000
 @@ -2634,8 +2634,8 @@ casts like @code{(unsigned) -1}.
  @cindex signed and unsigned values, comparison warning
  Warn when a comparison between signed and unsigned values could produce
  an incorrect result when the signed value is converted to unsigned.
 -This warning is also enabled by @option{-W}; to get the other warnings
 -of @option{-W} without this warning, use @samp{-W -Wno-sign-compare}.
 +This warning is enabled by @option{-W}, and by @option{-Wall}
 +in C++ only.
  
  @item -Waggregate-return
  @opindex Waggregate-return
 ===================================================================
 Index: testsuite/g++.dg/warn/compare1.C
 --- testsuite/g++.dg/warn/compare1.C	1 Jan 1970 00:00:00 -0000
 +++ testsuite/g++.dg/warn/compare1.C	2 May 2003 20:38:23 -0000
 @@ -0,0 +1,10 @@
 +/* -Wall is supposed to trigger -Wsign-compare for C++.  PR 10604.
 +   See also gcc.dg/compare7.c.  */
 +
 +/* { dg-do compile } */
 +/* { dg-options "-Wall" } */
 +
 +int f(unsigned a, int b)
 +{
 +  return a < b;  /* { dg-warning "signed and unsigned" } */
 +}
 ===================================================================
 Index: testsuite/gcc.dg/compare7.c
 --- testsuite/gcc.dg/compare7.c	1 Jan 1970 00:00:00 -0000
 +++ testsuite/gcc.dg/compare7.c	2 May 2003 20:38:24 -0000
 @@ -0,0 +1,10 @@
 +/* -Wall is not supposed to trigger -Wsign-compare for C.  PR 10604.
 +   See also g++.dg/warn/compare1.C.  */
 +
 +/* { dg-do compile } */
 +/* { dg-options "-Wall" } */
 +
 +int f(unsigned a, int b)
 +{
 +  return a < b;  /* { dg-bogus "signed and unsigned" } */
 +}