[PR c/25892]: disable -Wpointer-sign by default

[Alexandre Oliva <aoliva at redhat dot com>]

This patch implements the AFAIK-agreed-by-SC-and-RMS behavior for
-Wpointer-sign, removing the only blocker for GCC 4.1.  Branch
bootstrapped and regression tested on amd64-linux-gnu.  Ok for branch
and mainline, if forward-porting proves to be trivial?

Index: gcc/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR c/25892
	* c.opt (Wpointer-sign): Init to -1.
	* c-opts.c (c_common_handle_option): Set to 1 on OPT_Wall and
	OPT_pedantic, to 0 otherwise.
	* doc/invoke.texi: Update.
	
Index: gcc/testsuite/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR c/25892
	* gcc.dg/Wpointer-sign.c: New.
	* gcc.dg/Wpointer-sign-Wall.c: New.
	* gcc.dg/Wpointer-sign-Wall-no.c: New.
	* gcc.dg/Wpointer-sign-pedantic.c: New.
	* gcc.dg/Wpointer-sign-pedantic-no.c: New.
	* gcc.dg/conv-2.c: Use -Wpointer-sign.

Index: gcc/c.opt
===================================================================
--- gcc/c.opt.orig	2006-01-25 16:01:26.000000000 -0200
+++ gcc/c.opt	2006-01-25 16:02:28.000000000 -0200
@@ -420,7 +420,7 @@ C ObjC C++ ObjC++
 Give strings the type \"array of char\"
 
 Wpointer-sign
-C ObjC Var(warn_pointer_sign) Init(1)
+C ObjC Var(warn_pointer_sign) Init(-1)
 Warn when a pointer differs in signedness in an assignment
 
 ansi
Index: gcc/c-opts.c
===================================================================
--- gcc/c-opts.c.orig	2006-01-25 16:01:26.000000000 -0200
+++ gcc/c-opts.c	2006-01-25 16:02:28.000000000 -0200
@@ -413,6 +413,9 @@ c_common_handle_option (size_t scode, co
       cpp_opts->warn_comments = value;
       cpp_opts->warn_num_sign_change = value;
       cpp_opts->warn_multichar = value;	/* Was C++ only.  */
+
+      if (warn_pointer_sign == -1)
+	warn_pointer_sign = 1;
       break;
 
     case OPT_Wcomment:
@@ -874,6 +877,8 @@ c_common_handle_option (size_t scode, co
     case OPT_pedantic:
       cpp_opts->pedantic = 1;
       cpp_opts->warn_endif_labels = 1;
+      if (warn_pointer_sign == -1)
+	warn_pointer_sign = 1;
       break;
 
     case OPT_print_objc_runtime_info:
@@ -994,6 +999,11 @@ c_common_post_options (const char **pfil
   if (warn_missing_field_initializers == -1)
     warn_missing_field_initializers = extra_warnings;
 
+  /* -Wpointer_sign is disabled by default, but it is enabled if any
+     of -Wall or -pedantic are given.  */
+  if (warn_pointer_sign == -1)
+    warn_pointer_sign = 0;
+
   /* Special format checking options don't work without -Wformat; warn if
      they are used.  */
   if (!warn_format)
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi.orig	2006-01-25 16:01:26.000000000 -0200
+++ gcc/doc/invoke.texi	2006-01-25 16:02:28.000000000 -0200
@@ -251,7 +251,7 @@ Objective-C and Objective-C++ Dialects}.
 @gccoptlist{-Wbad-function-cast  -Wmissing-declarations @gol
 -Wmissing-prototypes  -Wnested-externs  -Wold-style-definition @gol
 -Wstrict-prototypes  -Wtraditional @gol
--Wdeclaration-after-statement -Wno-pointer-sign}
+-Wdeclaration-after-statement -Wpointer-sign}
 
 @item Debugging Options
 @xref{Debugging Options,,Options for Debugging Your Program or GCC}.
@@ -3385,11 +3385,13 @@ effectively.  Often, the problem is that
 complex; GCC will refuse to optimize programs when the optimization
 itself is likely to take inordinate amounts of time.
 
-@item -Wno-pointer-sign
+@item -Wpointer-sign
+@opindex Wpointer-sign
 @opindex Wno-pointer-sign
-Don't warn for pointer argument passing or assignment with different signedness.
-Only useful in the negative form since this warning is enabled by default.
-This option is only supported for C and Objective-C@.
+Warn for pointer argument passing or assignment with different signedness.
+This option is only supported for C and Objective-C@.  It is implied by
+@option{-Wall} and by @option{-pedantic}, which can be disabled with
+@option{-Wno-pointer-sign}.
 
 @item -Werror
 @opindex Werror
Index: gcc/testsuite/gcc.dg/Wpointer-sign.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gcc/testsuite/gcc.dg/Wpointer-sign.c	2006-01-25 23:22:24.000000000 -0200
@@ -0,0 +1,13 @@
+/* This is from PR c/25892.  The SC promised RMS that -Wpointer-sign
+   would be off by default in GCC 4.1 to avoid inconvenient warnings
+   while compiling GNU Emacs.  It should be enabled with -Wall and/or
+   -pedantic, though.  Make sure it's off by default in this test (so
+   use dg-options "" to avoid passing -pedantic-errors).  */
+
+/* { dg-options "" } */
+
+void foo(unsigned long* ulp);
+
+void bar(long* lp) {
+  foo(lp);
+}
Index: gcc/testsuite/gcc.dg/Wpointer-sign-Wall-no.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gcc/testsuite/gcc.dg/Wpointer-sign-Wall-no.c	2006-01-25 16:02:28.000000000 -0200
@@ -0,0 +1,9 @@
+/* This is from PR c/25892.  See Wpointer-sign.c for more details.  */
+
+/* { dg-options "-Wno-pointer-sign -Wall" } */
+
+void foo(unsigned long* ulp);
+
+void bar(long* lp) {
+  foo(lp);
+}
Index: gcc/testsuite/gcc.dg/Wpointer-sign-Wall.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gcc/testsuite/gcc.dg/Wpointer-sign-Wall.c	2006-01-25 16:02:28.000000000 -0200
@@ -0,0 +1,9 @@
+/* This is from PR c/25892.  See Wpointer-sign.c for more details.  */
+
+/* { dg-options "-Wall" } */
+
+void foo(unsigned long* ulp);
+
+void bar(long* lp) {
+  foo(lp); /* { dg-warning "differ in signedness" } */
+}
Index: gcc/testsuite/gcc.dg/Wpointer-sign-pedantic-no.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gcc/testsuite/gcc.dg/Wpointer-sign-pedantic-no.c	2006-01-25 16:02:28.000000000 -0200
@@ -0,0 +1,9 @@
+/* This is from PR c/25892.  See Wpointer-sign.c for more details.  */
+
+/* { dg-options "-Wno-pointer-sign -pedantic" } */
+
+void foo(unsigned long* ulp);
+
+void bar(long* lp) {
+  foo(lp);
+}
Index: gcc/testsuite/gcc.dg/Wpointer-sign-pedantic.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ gcc/testsuite/gcc.dg/Wpointer-sign-pedantic.c	2006-01-25 16:02:28.000000000 -0200
@@ -0,0 +1,9 @@
+/* This is from PR c/25892.  See Wpointer-sign.c for more details.  */
+
+/* { dg-options "-pedantic" } */
+
+void foo(unsigned long* ulp);
+
+void bar(long* lp) {
+  foo(lp); /* { dg-warning "differ in signedness" } */
+}
Index: gcc/testsuite/gcc.dg/conv-2.c
===================================================================
--- gcc/testsuite/gcc.dg/conv-2.c.orig	2006-01-25 23:20:06.000000000 -0200
+++ gcc/testsuite/gcc.dg/conv-2.c	2006-01-25 23:23:24.000000000 -0200
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "" } */
+/* { dg-options "-Wpointer-sign" } */
 
 void f1(long *);
 void f2(unsigned long *);

-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}