Public SourceMage Discussion List

[Remko van der Vossen <wich AT yuugen.jp>]

as_needed will add -Wl,--as-needed to LDFLAGS, which will cause the linker to
emit DT_NEEDED entries only for directly used libraries. This prevents 
programs
and libraries that only indirectly depend on some library from breaking when
that library has an soname change. A scenario which is very common with 
libtool
using build processes.
---
 usr/sbin/sorcery                   | 4 +++-
 var/lib/sorcery/modules/libsorcery | 7 ++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/usr/sbin/sorcery b/usr/sbin/sorcery
index 53bc512..c58f921 100755
--- a/usr/sbin/sorcery
+++ b/usr/sbin/sorcery
@@ -750,6 +750,7 @@ optimization_menu(){
   local    SPEEDY_HELP="Optimize generated code, conflicts with 'tiny' 
(CFLAGS=$FAST)"
   local     STRIP_HELP="Remove all symbol table and relocation (debugging) 
information (LDFLAGS=-s)"
   local      TINY_HELP="Optimize to smaller generated code, conflicts with 
'speedy' (CFLAGS=$SMALL)"
+  local AS_NEEDED_HELP="Only emit DT_NEEDED entries for directly used 
libraries (LDFLAGS=-Wl,--as-needed)"
 
   if  OPTIMIZATIONS=`eval $DIALOG '  --title  "$OPT_TITLE"     \
                               --no-cancel               \
@@ -762,7 +763,8 @@ optimization_menu(){
         "risky"     "          +speed"  "$RISKY"     "$RISKY_HELP"     \
         "speedy"    "  +size  ++speed"  "$SPEEDY"    "$SPEEDY_HELP"    \
         "strip"     " --size"           "$STRIP"     "$STRIP_HELP"     \
-        "tiny"      "  -size   +speed"  "$TINY"      "$TINY_HELP"'`
+        "tiny"      "  -size   +speed"  "$TINY"      "$TINY_HELP"      \
+        "as_needed" "only direct libs"  "$AS_NEEDED" "$AS_NEEDED_HELP"'`
   then
 
     OPTIMIZATIONS=`echo  ${OPTIMIZATIONS}  |  tr  '\n'  ' '`
diff --git a/var/lib/sorcery/modules/libsorcery 
b/var/lib/sorcery/modules/libsorcery
index 2abd865..c89f0ae 100755
--- a/var/lib/sorcery/modules/libsorcery
+++ b/var/lib/sorcery/modules/libsorcery
@@ -617,7 +617,7 @@ function optimize()  {
   debug "libsorcery" "In optimize()"
 
   unset  CFLAGS CXXFLAGS LDFLAGS CPPFLAGS
-  unset  FAST PRELINK RISKY SMALL SPEEDY STRIP TINY
+  unset  FAST PRELINK RISKY SMALL SPEEDY STRIP TINY AS_NEEDED
 
   # if user specified --no-opts then use only the args from the command line
   # otherwise do the normal stuff
@@ -663,6 +663,11 @@ function optimize()  {
           TINY="on"
           ;;
 
+        as_needed)
+          LDFLAGS="$LDFLAGS -Wl,--as-needed"
+          AS_NEEDED="on"
+          ;;
+
       esac
     done
     # use echo to crunch all the whitespace out for broken configure scripts
-- 
1.9.0