Make another try at using -Wl,--as-needed to suppress linking of unnecessary

shared libraries.  We've tried this before and had problems with libreadline
not linking properly on some platforms, but that seems to be a libreadline
bug that may have been fixed by now.  In any case, it's early enough in the
8.4 devel cycle that we can afford to have some transient breakage while
we work out any portability problems.

On Darwin, we try -Wl,-dead_strip_dylibs, which seems to be the equivalent
incantation there.

config/c-compiler.m4

@@ -1,5 +1,5 @@
 # Macros to detect C compiler features
-# $PostgreSQL: pgsql/config/c-compiler.m4,v 1.16 2008/04/18 18:43:08 alvherre Exp $
+# $PostgreSQL: pgsql/config/c-compiler.m4,v 1.17 2008/05/18 20:13:12 tgl Exp $
 
 
 # PGAC_C_SIGNED
@@ -110,3 +110,19 @@ _AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
                    [CFLAGS="$pgac_save_CFLAGS"
                     AC_MSG_RESULT(no)])
 ])# PGAC_PROG_CC_CFLAGS_OPT
+
+
+
+# PGAC_PROG_CC_LDFLAGS_OPT
+# ------------------------
+# Given a string, check if the compiler supports the string as a
+# command-line option. If it does, add the string to LDFLAGS.
+AC_DEFUN([PGAC_PROG_CC_LDFLAGS_OPT],
+[AC_MSG_CHECKING([if $CC supports $1])
+pgac_save_LDFLAGS=$LDFLAGS
+LDFLAGS="$pgac_save_LDFLAGS $1"
+AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+               AC_MSG_RESULT(yes),
+               [LDFLAGS="$pgac_save_LDFLAGS"
+                AC_MSG_RESULT(no)])
+])# PGAC_PROG_CC_LDFLAGS_OPT

configure

@@ -4318,6 +4318,116 @@ 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`"

configure.in

@@ -1,5 +1,5 @@
 dnl Process this file with autoconf to produce a configure script.
-dnl $PostgreSQL: pgsql/configure.in,v 1.560 2008/05/03 00:24:05 adunstan Exp $
+dnl $PostgreSQL: pgsql/configure.in,v 1.561 2008/05/18 20:13:12 tgl Exp $
 dnl
 dnl Developers, please strive to achieve this order:
 dnl
@@ -450,6 +450,16 @@ 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`"