Disable _FILE_OFFSET_BITS if the compiler defaults to it

Even though building glibc with LFS flags is not supported, and the
the usual way is to patch the build system to avoid it [1]; some system
do enable it by default, and it increases the requirements to build
glibc in such cases (it also does not help newcomers when trying
to build glibc).

The conform namespace and linknamespace tests also do not expect
that flag to be set by default, so disable it as well.

Checked with a build/check for major ABI and some (i386, arm,
mipsel, hppa) with a toolchain that has LFS flags by default.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=31624
Reviewed-by: DJ Delorie <dj@redhat.com>

diff --git a/Makeconfig b/Makeconfig
index a87ff7b1d3e62e8f9e831b7672777bbca0be66b3..c0c89e668567f9d94066fb2badfff4c856924f11 100644 (file)
--- a/Makeconfig
+++ b/Makeconfig
@@ -1011,6 +1011,9 @@ else
 +cflags += $(no-fortify-source)
 endif
 
+# Filter out LFS flags if compiler defines it by default.
++cflags += $(no-file-offset-bits-source)
+
 # Each sysdeps directory can contain header files that both will be
 # used to compile and will be installed.  Each can also contain an
 # include/ subdirectory, whose header files will be used to compile

diff --git a/configure b/configure
index 58bfb2917f9c122a427e110769cec56bb39a7490..5b9cc51067c2c4e12a362ca24dc6a05b4045bd4f 100755 (executable)
--- a/configure
+++ b/configure
@@ -635,6 +635,7 @@ libc_cv_gcc_unwind_find_fde
 libc_extra_cppflags
 libc_extra_cflags
 libc_cv_cxx_thread_local
+no_file_offset_bits_source
 fortify_source
 no_fortify_source
 libc_cv_fortify_source
@@ -7784,6 +7785,37 @@ fi
 config_vars="$config_vars
 supported-fortify = $libc_cv_supported_fortify_source"
 
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main (void)
+{
+
+#ifndef _FILE_OFFSET_BITS
+# error _FILE_OFFSET_BITS not defined
+#endif
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_cpp "$LINENO"
+then :
+  libc_cv_compiler_default_file_offset_bits=yes
+else case e in #(
+  e) libc_cv_compiler_default_file_offset_bits=no ;;
+esac
+fi
+rm -f conftest.err conftest.i conftest.$ac_ext
+if test "$libc_cv_compiler_default_file_offset_bits" = yes
+then :
+  no_file_offset_bits_source="-U_FILE_OFFSET_BITS"
+fi
+
+config_vars="$config_vars
+no-file-offset-bits-source = $no_file_offset_bits_source"
+
+
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether the assembler requires one version per symbol" >&5
 printf %s "checking whether the assembler requires one version per symbol... " >&6; }
 if test ${libc_cv_symver_needs_alias+y}

diff --git a/configure.ac b/configure.ac
index 5af742ce41366464a3e104369615853d36e4d763..160c86341636e5f74f8bec81b266e8205fff5d08 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1564,6 +1564,19 @@ AC_SUBST(no_fortify_source)
 AC_SUBST(fortify_source)
 LIBC_CONFIG_VAR([supported-fortify], [$libc_cv_supported_fortify_source])
 
+dnl Check if compiler define _FILE_OFFSET_BITS by default
+AC_PREPROC_IFELSE([AC_LANG_PROGRAM([[]], [[
+#ifndef _FILE_OFFSET_BITS
+# error _FILE_OFFSET_BITS not defined
+#endif]])],
+              [libc_cv_compiler_default_file_offset_bits=yes],
+              [libc_cv_compiler_default_file_offset_bits=no])
+AS_IF([test "$libc_cv_compiler_default_file_offset_bits" = yes],
+      [no_file_offset_bits_source="-U_FILE_OFFSET_BITS"])
+AC_SUBST(no_file_offset_bits_source)
+LIBC_CONFIG_VAR([no-file-offset-bits-source], [$no_file_offset_bits_source])
+
+
 dnl Starting with binutils 2.35, GAS can attach multiple symbol versions
 dnl to one symbol (PR 23840).
 AC_CACHE_CHECK(whether the assembler requires one version per symbol,

diff --git a/conform/Makefile b/conform/Makefile
index 73a3cb6da2e99d8018c52263a1aa90f070056a77..50293a195b335916b97a340e2a20a358e7c7d1e4 100644 (file)
--- a/conform/Makefile
+++ b/conform/Makefile
@@ -372,7 +372,7 @@ test-xfail-UNIX98/ndbm.h/conform = yes
 test-xfail-XOPEN2K/ndbm.h/conform = yes
 test-xfail-XOPEN2K8/ndbm.h/conform = yes
 
-conformtest-cc-flags = -I../include $(+sysdep-includes) $(sysincludes) -I..
+conformtest-cc-flags =  -I../include $(+sysdep-includes) $(sysincludes) -I.. $(no-file-offset-bits-source)
 # conformtest-xfail-conds may be set by a sysdeps Makefile fragment to
 # a list of conditions that are considered to be true when encountered
 # in xfail[cond]- lines in test expectations.