Adjust -Wl,--asneeded test to avoid using the switch if it breaks

libreadline.  What we will do for compatibility :-(

config/c-compiler.m4

 # Macros to detect C compiler features
-# $PostgreSQL: pgsql/config/c-compiler.m4,v 1.17 2008/05/18 20:13:12 tgl Exp $
+# $PostgreSQL: pgsql/config/c-compiler.m4,v 1.18 2008/05/20 03:30:21 tgl Exp $
 
 
 # PGAC_C_SIGNED
@@ -117,11 +117,13 @@ _AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
 # ------------------------
 # Given a string, check if the compiler supports the string as a
 # command-line option. If it does, add the string to LDFLAGS.
+# For reasons you'd really rather not know about, this checks whether
+# you can link to a particular function, not just whether you can link.
 AC_DEFUN([PGAC_PROG_CC_LDFLAGS_OPT],
 [AC_MSG_CHECKING([if $CC supports $1])
 pgac_save_LDFLAGS=$LDFLAGS
 LDFLAGS="$pgac_save_LDFLAGS $1"
-AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+AC_LINK_IFELSE([AC_LANG_CALL([],[$2])],
                AC_MSG_RESULT(yes),
                [LDFLAGS="$pgac_save_LDFLAGS"
                 AC_MSG_RESULT(no)])

configure

@@ -3977,9 +3977,6 @@ echo "$as_me: error: --enable-profiling is supported only when using GCC" >&2;}
   fi
 fi
 
-{ echo "$as_me:$LINENO: using CFLAGS=$CFLAGS" >&5
-echo "$as_me: using CFLAGS=$CFLAGS" >&6;}
-
 # We already have this in Makefile.win32, but configure needs it too
 if test "$PORTNAME" = "win32"; then
   CPPFLAGS="$CPPFLAGS -I$srcdir/src/include/port/win32 -DEXEC_BACKEND"
@@ -4318,116 +4315,6 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 
-# If compiler will take -Wl,--as-needed then add that to LDFLAGS.
-# This is much easier than trying to filter LIBS to the minimum for each
-# executable.  (Note that shared libraries won't use this switch, though.)
-# On Darwin it's spelled -Wl,-dead_strip_dylibs, but don't try that elsewhere
-if test "$PORTNAME" != "darwin"; then
-  { echo "$as_me:$LINENO: checking if $CC supports -Wl,--as-needed" >&5
-echo $ECHO_N "checking if $CC supports -Wl,--as-needed... $ECHO_C" >&6; }
-pgac_save_LDFLAGS=$LDFLAGS
-LDFLAGS="$pgac_save_LDFLAGS -Wl,--as-needed"
-cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-
-int
-main ()
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-rm -f conftest.$ac_objext conftest$ac_exeext
-if { (ac_try="$ac_link"
-case "(($ac_try" in
-  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
-  *) ac_try_echo=$ac_try;;
-esac
-eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
-  (eval "$ac_link") 2>conftest.er1
-  ac_status=$?
-  grep -v '^ *+' conftest.er1 >conftest.err
-  rm -f conftest.er1
-  cat conftest.err >&5
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); } && {
-	 test -z "$ac_c_werror_flag" ||
-	 test ! -s conftest.err
-       } && test -s conftest$ac_exeext &&
-       $as_test_x conftest$ac_exeext; then
-  { echo "$as_me:$LINENO: result: yes" >&5
-echo "${ECHO_T}yes" >&6; }
-else
-  echo "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-	LDFLAGS="$pgac_save_LDFLAGS"
-                { echo "$as_me:$LINENO: result: no" >&5
-echo "${ECHO_T}no" >&6; }
-fi
-
-rm -f core conftest.err conftest.$ac_objext conftest_ipa8_conftest.oo \
-      conftest$ac_exeext conftest.$ac_ext
-
-else
-  { echo "$as_me:$LINENO: checking if $CC supports -Wl,-dead_strip_dylibs" >&5
-echo $ECHO_N "checking if $CC supports -Wl,-dead_strip_dylibs... $ECHO_C" >&6; }
-pgac_save_LDFLAGS=$LDFLAGS
-LDFLAGS="$pgac_save_LDFLAGS -Wl,-dead_strip_dylibs"
-cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-
-int
-main ()
-{
-
-  ;
-  return 0;
-}
-_ACEOF
-rm -f conftest.$ac_objext conftest$ac_exeext
-if { (ac_try="$ac_link"
-case "(($ac_try" in
-  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
-  *) ac_try_echo=$ac_try;;
-esac
-eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
-  (eval "$ac_link") 2>conftest.er1
-  ac_status=$?
-  grep -v '^ *+' conftest.er1 >conftest.err
-  rm -f conftest.er1
-  cat conftest.err >&5
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); } && {
-	 test -z "$ac_c_werror_flag" ||
-	 test ! -s conftest.err
-       } && test -s conftest$ac_exeext &&
-       $as_test_x conftest$ac_exeext; then
-  { echo "$as_me:$LINENO: result: yes" >&5
-echo "${ECHO_T}yes" >&6; }
-else
-  echo "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-	LDFLAGS="$pgac_save_LDFLAGS"
-                { echo "$as_me:$LINENO: result: no" >&5
-echo "${ECHO_T}no" >&6; }
-fi
-
-rm -f core conftest.err conftest.$ac_objext conftest_ipa8_conftest.oo \
-      conftest$ac_exeext conftest.$ac_ext
-
-fi
-
 # Create compiler version string
 if test x"$GCC" = x"yes" ; then
   cc_string="GCC `${CC} --version | sed q`"
@@ -5596,11 +5483,6 @@ rm -f conftest*
 CPPFLAGS="$CPPFLAGS $INCLUDES"
 LDFLAGS="$LDFLAGS $LIBDIRS"
 
-{ echo "$as_me:$LINENO: using CPPFLAGS=$CPPFLAGS" >&5
-echo "$as_me: using CPPFLAGS=$CPPFLAGS" >&6;}
-{ echo "$as_me:$LINENO: using LDFLAGS=$LDFLAGS" >&5
-echo "$as_me: using LDFLAGS=$LDFLAGS" >&6;}
-
 
 
 
@@ -25749,6 +25631,148 @@ echo "$as_me: WARNING: *** skipping thread test on Win32" >&2;}
 fi
 fi
 
+# If compiler will take -Wl,--as-needed then add that to LDFLAGS.
+# This is much easier than trying to filter LIBS to the minimum for each
+# executable.  (Note that shared libraries won't use this switch, though.)
+# On (at least) some Red-Hat-derived systems, this switch breaks linking to
+# libreadline; therefore we postpone testing it until we know what library
+# dependencies readline has.  The test code will try to link with $LIBS.
+if test "$with_readline" = yes; then
+  link_test_func=readline
+else
+  link_test_func=exit
+fi
+if test "$PORTNAME" != "darwin"; then
+  { echo "$as_me:$LINENO: checking if $CC supports -Wl,--as-needed" >&5
+echo $ECHO_N "checking if $CC supports -Wl,--as-needed... $ECHO_C" >&6; }
+pgac_save_LDFLAGS=$LDFLAGS
+LDFLAGS="$pgac_save_LDFLAGS -Wl,--as-needed"
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* 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 $link_test_func ();
+int
+main ()
+{
+return $link_test_func ();
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_link") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext &&
+       $as_test_x conftest$ac_exeext; then
+  { echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	LDFLAGS="$pgac_save_LDFLAGS"
+                { echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest_ipa8_conftest.oo \
+      conftest$ac_exeext conftest.$ac_ext
+
+else
+  # On Darwin it's spelled -Wl,-dead_strip_dylibs, but don't try that elsewhere
+  { echo "$as_me:$LINENO: checking if $CC supports -Wl,-dead_strip_dylibs" >&5
+echo $ECHO_N "checking if $CC supports -Wl,-dead_strip_dylibs... $ECHO_C" >&6; }
+pgac_save_LDFLAGS=$LDFLAGS
+LDFLAGS="$pgac_save_LDFLAGS -Wl,-dead_strip_dylibs"
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* 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 $link_test_func ();
+int
+main ()
+{
+return $link_test_func ();
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_link") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext &&
+       $as_test_x conftest$ac_exeext; then
+  { echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	LDFLAGS="$pgac_save_LDFLAGS"
+                { echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest_ipa8_conftest.oo \
+      conftest$ac_exeext conftest.$ac_ext
+
+fi
+
+
+# Begin output steps
+
+{ echo "$as_me:$LINENO: using CFLAGS=$CFLAGS" >&5
+echo "$as_me: using CFLAGS=$CFLAGS" >&6;}
+{ echo "$as_me:$LINENO: using CPPFLAGS=$CPPFLAGS" >&5
+echo "$as_me: using CPPFLAGS=$CPPFLAGS" >&6;}
+{ echo "$as_me:$LINENO: using LDFLAGS=$LDFLAGS" >&5
+echo "$as_me: using LDFLAGS=$LDFLAGS" >&6;}
+
 # prepare build tree if outside source tree
 # Note 1: test -ef might not exist, but it's more reliable than `pwd`.
 # Note 2: /bin/pwd might be better than shell's built-in at getting

configure.in

 dnl Process this file with autoconf to produce a configure script.
-dnl $PostgreSQL: pgsql/configure.in,v 1.561 2008/05/18 20:13:12 tgl Exp $
+dnl $PostgreSQL: pgsql/configure.in,v 1.562 2008/05/20 03:30:22 tgl Exp $
 dnl
 dnl Developers, please strive to achieve this order:
 dnl
@@ -426,8 +426,6 @@ if test "$enable_profiling" = yes && test "$ac_cv_prog_cc_g" = yes; then
   fi
 fi
 
-AC_MSG_NOTICE([using CFLAGS=$CFLAGS])
-
 # We already have this in Makefile.win32, but configure needs it too
 if test "$PORTNAME" = "win32"; then
   CPPFLAGS="$CPPFLAGS -I$srcdir/src/include/port/win32 -DEXEC_BACKEND"
@@ -450,16 +448,6 @@ fi
 AC_PROG_CPP
 AC_SUBST(GCC)
 
-# If compiler will take -Wl,--as-needed then add that to LDFLAGS.
-# This is much easier than trying to filter LIBS to the minimum for each
-# executable.  (Note that shared libraries won't use this switch, though.)
-# On Darwin it's spelled -Wl,-dead_strip_dylibs, but don't try that elsewhere
-if test "$PORTNAME" != "darwin"; then
-  PGAC_PROG_CC_LDFLAGS_OPT([-Wl,--as-needed])
-else
-  PGAC_PROG_CC_LDFLAGS_OPT([-Wl,-dead_strip_dylibs])
-fi
-
 # Create compiler version string
 if test x"$GCC" = x"yes" ; then
   cc_string="GCC `${CC} --version | sed q`"
@@ -773,9 +761,6 @@ AC_SUBST(ELF_SYS)
 CPPFLAGS="$CPPFLAGS $INCLUDES"
 LDFLAGS="$LDFLAGS $LIBDIRS"
 
-AC_MSG_NOTICE([using CPPFLAGS=$CPPFLAGS])
-AC_MSG_NOTICE([using LDFLAGS=$LDFLAGS])
-
 AC_ARG_VAR(LDFLAGS_SL)
 
 PGAC_PROG_LD
@@ -1712,6 +1697,31 @@ AC_MSG_WARN([*** skipping thread test on Win32])
 fi
 fi
 
+# If compiler will take -Wl,--as-needed then add that to LDFLAGS.
+# This is much easier than trying to filter LIBS to the minimum for each
+# executable.  (Note that shared libraries won't use this switch, though.)
+# On (at least) some Red-Hat-derived systems, this switch breaks linking to
+# libreadline; therefore we postpone testing it until we know what library
+# dependencies readline has.  The test code will try to link with $LIBS.
+if test "$with_readline" = yes; then
+  link_test_func=readline
+else
+  link_test_func=exit
+fi
+if test "$PORTNAME" != "darwin"; then
+  PGAC_PROG_CC_LDFLAGS_OPT([-Wl,--as-needed], $link_test_func)
+else
+  # On Darwin it's spelled -Wl,-dead_strip_dylibs, but don't try that elsewhere
+  PGAC_PROG_CC_LDFLAGS_OPT([-Wl,-dead_strip_dylibs], $link_test_func)
+fi
+
+
+# Begin output steps
+
+AC_MSG_NOTICE([using CFLAGS=$CFLAGS])
+AC_MSG_NOTICE([using CPPFLAGS=$CPPFLAGS])
+AC_MSG_NOTICE([using LDFLAGS=$LDFLAGS])
+
 # prepare build tree if outside source tree
 # Note 1: test -ef might not exist, but it's more reliable than `pwd`.
 # Note 2: /bin/pwd might be better than shell's built-in at getting