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Use -Werror by default, add --disable-werror
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Wed, 26 Nov 2014 22:13:40 +0000
- Subject: Use -Werror by default, add --disable-werror
- Authentication-results: sourceware.org; auth=none
As discussed starting at
<https://sourceware.org/ml/libc-alpha/2014-11/msg00323.html>, this
patch makes the glibc build use -Werror by default to avoid
accidentally adding new warnings to the build. The configure option
--disable-werror can be used to disable this.
-Wno-error=undef is temporarily used because the build isn't clean
regarding -Wundef warnings. The idea is that once the remaining
-Wundef warnings have been cleaned up (in at least one configuration),
-Wno-error=undef will be removed.
I get a clean build and test on x86_64 (GCC 4.9 branch) with the
following patches applied before this one:
* To fix testsuite warnings (not using pragmas):
<https://sourceware.org/ml/libc-alpha/2014-11/msg00741.html>,
<https://sourceware.org/ml/libc-alpha/2014-11/msg00768.html>,
<https://sourceware.org/ml/libc-alpha/2014-11/msg00780.html>,
<https://sourceware.org/ml/libc-alpha/2014-11/msg00792.html>,
<https://sourceware.org/ml/libc-alpha/2014-11/msg00797.html>.
* To suppress testsuite warnings (using pragmas):
<https://sourceware.org/ml/libc-alpha/2014-11/msg00736.html>,
<https://sourceware.org/ml/libc-alpha/2014-11/msg00752.html>,
<https://sourceware.org/ml/libc-alpha/2014-11/msg00785.html>,
<https://sourceware.org/ml/libc-alpha/2014-11/msg00791.html>.
The expectation is that this may well break the build for some other
configurations, and people seeing such breakage should make
appropriate fixes to fix or suppress the warnings for their
configurations. In some cases that may involve using pragmas as the
right fix (I think that will be right for the -Wno-inline issue for
MIPS I referred to in
<https://sourceware.org/ml/libc-alpha/2012-11/msg00798.html>, for
example), in some cases -Wno-error in sysdeps makefiles (__restore_rt
in MIPS sigaction, for example), in some cases substantive fixes for
the warnings.
Note that if, with a view to fixing things before the build breaks,
you just look for "warning:" in test output, you'll see lots of
warnings from the linker about functions such as tmpnam. Those
warnings can be ignored - only compiler warnings are relevant to
-Werror, not linker warnings.
2014-11-26 Joseph Myers <joseph@codesourcery.com>
* configure.ac (--disable-werror): New configure option.
(enable_werror): New AC_SUBST.
* configure: Regenerated.
* config.make.in (enable-werror): New variable.
* Makeconfig [$(enable-werror) = yes] (+gccwarn): Add -Werror
-Wno-error=undef.
(+gccwarn-c): Do not use -Werror=implicit-function-declaration.
* manual/install.texi (Configuring and compiling): Document
--disable-werror.
* INSTALL: Regenerated.
* debug/Makefile (CFLAGS-tst-chk1.c): Add -Wno-error.
(CFLAGS-tst-chk2.c): Likewise.
(CFLAGS-tst-chk3.c): Likewise.
(CFLAGS-tst-chk4.cc): Likewise.
(CFLAGS-tst-chk5.cc): Likewise.
(CFLAGS-tst-chk6.cc): Likewise.
(CFLAGS-tst-lfschk1.c): Likewise.
(CFLAGS-tst-lfschk2.c): Likewise.
(CFLAGS-tst-lfschk3.c): Likewise.
(CFLAGS-tst-lfschk4.cc): Likewise.
(CFLAGS-tst-lfschk5.cc): Likewise.
(CFLAGS-tst-lfschk6.cc): Likewise.
diff --git a/INSTALL b/INSTALL
index dac6178..dd5c34a 100644
--- a/INSTALL
+++ b/INSTALL
@@ -143,6 +143,13 @@ will be used, and CFLAGS sets optimization options for the compiler.
additional security risks to the system and you should enable it
only if you understand and accept those risks.
+`--disable-werror'
+ By default, the GNU C Library is built with `-Werror'. If you wish
+ to build without this option (for example, if building with a newer
+ version of GCC than this version of the GNU C Library was tested
+ with, so new warnings cause the build with `-Werror' to fail), you
+ can configure with `--disable-werror'.
+
`--build=BUILD-SYSTEM'
`--host=HOST-SYSTEM'
These options are for cross-compiling. If you specify both
diff --git a/Makeconfig b/Makeconfig
index bbf5460..1555368 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -717,7 +717,10 @@ else
+gccwarn := -Wall -Wwrite-strings -Winline
endif
+gccwarn += -Wundef
-+gccwarn-c = -Wstrict-prototypes -Werror=implicit-function-declaration
+ifeq ($(enable-werror),yes)
++gccwarn += -Werror -Wno-error=undef
+endif
++gccwarn-c = -Wstrict-prototypes
# We do not depend on the address of constants in different files to be
# actually different, so allow the compiler to merge them all.
diff --git a/NEWS b/NEWS
index 8f8203b..8d946db 100644
--- a/NEWS
+++ b/NEWS
@@ -24,6 +24,9 @@ Version 2.21
C Library is GCC 4.6. Older GCC versions, and non-GNU compilers, can
still be used to compile programs using the GNU C Library.
+* The GNU C Library is now built with -Werror by default. This can be
+ disabled by configuring with --disable-werror.
+
* New locales: tu_IN, bh_IN.
* The obsolete sigvec function has been removed. This was the original
diff --git a/config.make.in b/config.make.in
index 4a781fd..ad4dd30 100644
--- a/config.make.in
+++ b/config.make.in
@@ -45,6 +45,7 @@ sysheaders = @sysheaders@
sysincludes = @SYSINCLUDES@
c++-sysincludes = @CXX_SYSINCLUDES@
all-warnings = @all_warnings@
+enable-werror = @enable_werror@
have-z-combreloc = @libc_cv_z_combreloc@
have-z-execstack = @libc_cv_z_execstack@
diff --git a/configure b/configure
index 0cb54ec..b1fda38 100755
--- a/configure
+++ b/configure
@@ -668,6 +668,7 @@ build_pt_chown
build_nscd
link_obsolete_rpc
libc_cv_nss_crypt
+enable_werror
all_warnings
force_install
bindnow
@@ -767,6 +768,7 @@ enable_force_install
enable_maintainer_mode
enable_kernel
enable_all_warnings
+enable_werror
enable_multi_arch
enable_nss_crypt
enable_obsolete_rpc
@@ -1428,6 +1430,7 @@ Optional Features:
--enable-kernel=VERSION compile for compatibility with kernel not older than
VERSION
--enable-all-warnings enable all useful warnings gcc can issue
+ --disable-werror do not build with -Werror
--enable-multi-arch enable single DSO with optimizations for multiple
architectures
--enable-nss-crypt enable libcrypt to use nss
@@ -3565,6 +3568,15 @@ fi
+# Check whether --enable-werror was given.
+if test "${enable_werror+set}" = set; then :
+ enableval=$enable_werror; enable_werror=$enableval
+else
+ enable_werror=yes
+fi
+
+
+
# Check whether --enable-multi-arch was given.
if test "${enable_multi_arch+set}" = set; then :
enableval=$enable_multi_arch; multi_arch=$enableval
diff --git a/configure.ac b/configure.ac
index b2c4b1f..784e360 100644
--- a/configure.ac
+++ b/configure.ac
@@ -253,6 +253,13 @@ AC_ARG_ENABLE([all-warnings],
[])
AC_SUBST(all_warnings)
+AC_ARG_ENABLE([werror],
+ AC_HELP_STRING([--disable-werror],
+ [do not build with -Werror]),
+ [enable_werror=$enableval],
+ [enable_werror=yes])
+AC_SUBST(enable_werror)
+
AC_ARG_ENABLE([multi-arch],
AC_HELP_STRING([--enable-multi-arch],
[enable single DSO with optimizations for multiple architectures]),
diff --git a/debug/Makefile b/debug/Makefile
index 3ddcd1e..96c21d5 100644
--- a/debug/Makefile
+++ b/debug/Makefile
@@ -96,19 +96,21 @@ CFLAGS-tst-longjmp_chk3.c = -fexceptions -fasynchronous-unwind-tables
CPPFLAGS-tst-longjmp_chk3.c = -D_FORTIFY_SOURCE=1
# We know these tests have problems with format strings, this is what
-# we are testing. Disable that warning.
-CFLAGS-tst-chk1.c = -Wno-format
-CFLAGS-tst-chk2.c = -Wno-format
-CFLAGS-tst-chk3.c = -Wno-format
-CFLAGS-tst-chk4.cc = -Wno-format
-CFLAGS-tst-chk5.cc = -Wno-format
-CFLAGS-tst-chk6.cc = -Wno-format
-CFLAGS-tst-lfschk1.c = -Wno-format
-CFLAGS-tst-lfschk2.c = -Wno-format
-CFLAGS-tst-lfschk3.c = -Wno-format
-CFLAGS-tst-lfschk4.cc = -Wno-format
-CFLAGS-tst-lfschk5.cc = -Wno-format
-CFLAGS-tst-lfschk6.cc = -Wno-format
+# we are testing. Disable that warning. They also generate warnings
+# from warning attributes, which cannot be disabled via pragmas, so
+# require -Wno-error to be used.
+CFLAGS-tst-chk1.c = -Wno-format -Wno-error
+CFLAGS-tst-chk2.c = -Wno-format -Wno-error
+CFLAGS-tst-chk3.c = -Wno-format -Wno-error
+CFLAGS-tst-chk4.cc = -Wno-format -Wno-error
+CFLAGS-tst-chk5.cc = -Wno-format -Wno-error
+CFLAGS-tst-chk6.cc = -Wno-format -Wno-error
+CFLAGS-tst-lfschk1.c = -Wno-format -Wno-error
+CFLAGS-tst-lfschk2.c = -Wno-format -Wno-error
+CFLAGS-tst-lfschk3.c = -Wno-format -Wno-error
+CFLAGS-tst-lfschk4.cc = -Wno-format -Wno-error
+CFLAGS-tst-lfschk5.cc = -Wno-format -Wno-error
+CFLAGS-tst-lfschk6.cc = -Wno-format -Wno-error
LDLIBS-tst-chk4 = -lstdc++
LDLIBS-tst-chk5 = -lstdc++
LDLIBS-tst-chk6 = -lstdc++
diff --git a/manual/install.texi b/manual/install.texi
index 1eafb6e..35467b1 100644
--- a/manual/install.texi
+++ b/manual/install.texi
@@ -174,6 +174,13 @@ setuid and owned by @code{root}. The use of @file{pt_chown} introduces
additional security risks to the system and you should enable it only if
you understand and accept those risks.
+@item --disable-werror
+By default, @theglibc{} is built with @option{-Werror}. If you wish
+to build without this option (for example, if building with a newer
+version of GCC than this version of @theglibc{} was tested with, so
+new warnings cause the build with @option{-Werror} to fail), you can
+configure with @option{--disable-werror}.
+
@item --build=@var{build-system}
@itemx --host=@var{host-system}
These options are for cross-compiling. If you specify both options and
--
Joseph S. Myers
joseph@codesourcery.com