Re: [PATCH] gdb/configure: Replace hardcoded -ldl with check based on dlfcn.h availability

[Pavel Chupin <pavel.v.chupin@gmail.com>]

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On Tue, May 14, 2013 at 11:23 PM, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
>> From: Tom Tromey <tromey@redhat.com>
>> Date: Tue, 14 May 2013 13:00:10 -0600
>>
>> Mark> The fix isn't quite right.  OpenBSD for example has <dlfcn.h> but no
>> Mark> libdl; dlopen(3) and friends live in libc.
>>
>> Pavel> Hi Mark,
>> Pavel> Thanks for your comments. Please see new patch attached.
>>
>> Pavel> -    LIBS="-ldl $LIBS"
>> Pavel> +    AC_CHECK_LIB(dl, dlopen)
>>
>> I think it is probably better to use AC_SEARCH_LIBS.
>
> That's indeed what the autoconf manual suggests.

Please see attached.

ChangeLog entry didn't change:
2013-05-16  Pavel Chupin  <pavel.v.chupin@intel.com>

        Replace hardcoded -ldl with check for availability
        * acinclude.m4: Add check for dlopen in libdl.
        * configure.ac: Ditto.
        * configure: Regenerate.

Is it OK for trunk?

--
Pavel Chupin
Intel Corporation

[-- Attachment #2: 0001-Replace-hardcoded-ldl-with-check-for-availability-2.patch --]
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From f4972c4b995de564936a4e2048c926b84f79f7a6 Mon Sep 17 00:00:00 2001
From: Pavel Chupin <pavel.v.chupin@intel.com>
Date: Tue, 16 Apr 2013 16:05:20 +0400
Subject: [PATCH] Replace hardcoded -ldl with check for availability

Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>
---
 gdb/acinclude.m4 |   2 +-
 gdb/configure    | 228 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 gdb/configure.ac |   2 +-
 3 files changed, 226 insertions(+), 6 deletions(-)

diff --git a/gdb/acinclude.m4 b/gdb/acinclude.m4
index 25caddd..df7d8c0 100644
--- a/gdb/acinclude.m4
+++ b/gdb/acinclude.m4
@@ -455,7 +455,7 @@ AC_DEFUN([GDB_AC_CHECK_BFD], [
   intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
   # -ldl is provided by bfd/Makfile.am (LIBDL) <PLUGINS>.
   if test "$plugins" = "yes"; then
-    LIBS="-ldl $LIBS"
+    AC_SEARCH_LIBS(dlopen, dl)
   fi
   LIBS="-lbfd -liberty $intl $LIBS"
   AC_CACHE_CHECK([$1], [$2],
diff --git a/gdb/configure b/gdb/configure
index 6033791..32f1efa 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -12593,7 +12593,62 @@ esac
   intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
   # -ldl is provided by bfd/Makfile.am (LIBDL) <PLUGINS>.
   if test "$plugins" = "yes"; then
-    LIBS="-ldl $LIBS"
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing dlopen" >&5
+$as_echo_n "checking for library containing dlopen... " >&6; }
+if test "${ac_cv_search_dlopen+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char dlopen ();
+int
+main ()
+{
+return dlopen ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' dl; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_search_dlopen=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext
+  if test "${ac_cv_search_dlopen+set}" = set; then :
+  break
+fi
+done
+if test "${ac_cv_search_dlopen+set}" = set; then :
+
+else
+  ac_cv_search_dlopen=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_dlopen" >&5
+$as_echo "$ac_cv_search_dlopen" >&6; }
+ac_res=$ac_cv_search_dlopen
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+
   fi
   LIBS="-lbfd -liberty $intl $LIBS"
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ELF support in BFD" >&5
@@ -12635,7 +12690,62 @@ $as_echo "#define HAVE_ELF 1" >>confdefs.h
 
   # -ldl is provided by bfd/Makfile.am (LIBDL) <PLUGINS>.
   if test "$plugins" = "yes"; then
-    LIBS="-ldl $LIBS"
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing dlopen" >&5
+$as_echo_n "checking for library containing dlopen... " >&6; }
+if test "${ac_cv_search_dlopen+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char dlopen ();
+int
+main ()
+{
+return dlopen ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' dl; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_search_dlopen=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext
+  if test "${ac_cv_search_dlopen+set}" = set; then :
+  break
+fi
+done
+if test "${ac_cv_search_dlopen+set}" = set; then :
+
+else
+  ac_cv_search_dlopen=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_dlopen" >&5
+$as_echo "$ac_cv_search_dlopen" >&6; }
+ac_res=$ac_cv_search_dlopen
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+
   fi
 fi
 
@@ -12652,7 +12762,62 @@ fi
   intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
   # -ldl is provided by bfd/Makfile.am (LIBDL) <PLUGINS>.
   if test "$plugins" = "yes"; then
-    LIBS="-ldl $LIBS"
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing dlopen" >&5
+$as_echo_n "checking for library containing dlopen... " >&6; }
+if test "${ac_cv_search_dlopen+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char dlopen ();
+int
+main ()
+{
+return dlopen ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' dl; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_search_dlopen=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext
+  if test "${ac_cv_search_dlopen+set}" = set; then :
+  break
+fi
+done
+if test "${ac_cv_search_dlopen+set}" = set; then :
+
+else
+  ac_cv_search_dlopen=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_dlopen" >&5
+$as_echo "$ac_cv_search_dlopen" >&6; }
+ac_res=$ac_cv_search_dlopen
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+
   fi
   LIBS="-lbfd -liberty $intl $LIBS"
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for Mach-O support in BFD" >&5
@@ -12704,7 +12869,62 @@ fi
   intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
   # -ldl is provided by bfd/Makfile.am (LIBDL) <PLUGINS>.
   if test "$plugins" = "yes"; then
-    LIBS="-ldl $LIBS"
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing dlopen" >&5
+$as_echo_n "checking for library containing dlopen... " >&6; }
+if test "${ac_cv_search_dlopen+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_func_search_save_LIBS=$LIBS
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char dlopen ();
+int
+main ()
+{
+return dlopen ();
+  ;
+  return 0;
+}
+_ACEOF
+for ac_lib in '' dl; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_search_dlopen=$ac_res
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext
+  if test "${ac_cv_search_dlopen+set}" = set; then :
+  break
+fi
+done
+if test "${ac_cv_search_dlopen+set}" = set; then :
+
+else
+  ac_cv_search_dlopen=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_dlopen" >&5
+$as_echo "$ac_cv_search_dlopen" >&6; }
+ac_res=$ac_cv_search_dlopen
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
+
+fi
+
   fi
   LIBS="-lbfd -liberty $intl $LIBS"
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for SOM support in BFD" >&5
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 3e95c25..df2c919 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -2029,7 +2029,7 @@ if test $gdb_cv_var_elf = yes; then
 	    [Define if ELF support should be included.])
   # -ldl is provided by bfd/Makfile.am (LIBDL) <PLUGINS>.
   if test "$plugins" = "yes"; then
-    LIBS="-ldl $LIBS"
+    AC_SEARCH_LIBS(dlopen, dl)
   fi
 fi
 
-- 
1.7.11.4