PLDWWW: DevelopingPLD/AdvancedDeveloping/FixingAsNeeded

[sparky]

Author: sparky   Date: Mon Aug  7 00:53:37 2006 GMT
Module: PLDWWW   URL: http://www.pld-linux.org/DevelopingPLD/AdvancedDeveloping/FixingAsNeeded
---- Log message:


---- Page affected: DevelopingPLD/AdvancedDeveloping/FixingAsNeeded

---- Diffs:

================================================================
  $ gcc $(LDFLAGS) -o $@ $(OBJECTS) $(LIBS)
  }}}
  and this generally works well.
- 
+ ----
  If there is something like that:
  {{{
  $ gcc -Wl,--as-needed -l<library> <objects.o>
  }}}
  the library will __never__ be linked, because it's not required at the
  time it's checked.
- 
+ ----
  And with something like that:
  {{{
  $ gcc -l<library> -Wl,--as-needed <objects.o>
@@ -52, +52 @@

  [http://cvs.pld-linux.org/cgi-bin/cvsweb/SOURCES/readline-shared.patch?r1=1.6&r2=1.7 fixed readline];).
  
  But some packages link with readline or ncurses while they use __only__
- symbols from tinfo. 
+ symbols from tinfo.
  ''Without'' {{{--as-needed}}} those executables work because
- they are linked with tinfo from readline/ncurses library. 
+ they are linked with tinfo from readline/ncurses library.
  ''With'' {{{--as-needed}}} it will not work, because readline/ncurses
  contain no symbols required by executable
  so they are not linked, it's dependencies naturally are neither linked.
@@ -129, +129 @@

  What we get after running make in build tree:
  
  {{{
- x86_64-pld-linux-g++ -DNOMMGR -Wall -DGAMEDATADIR=\"/usr/share/xmoto\" -ggdb -O2 -Wl,--as-needed -o xmoto-edit BuiltInFont.o [...object files...] Packager.o  -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lSDL -lbz2 -lz -lpng -ljpeg 
+ x86_64-pld-linux-g++ -DNOMMGR -Wall -DGAMEDATADIR=\"/usr/share/xmoto\" -ggdb -O2 -Wl,--as-needed -o xmoto-edit BuiltInFont.o [...object files...] Packager.o  -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lSDL -lbz2 -lz -lpng -ljpeg
  
  VApp.o: In function `vapp::App::grabScreen()':
  src/VApp.cpp:667: undefined reference to `glReadBuffer'
@@ -213, +213 @@

  Compilation stops at this place:
  
  {{{
- /bin/sh ../libtool --tag=CC --mode=link x86_64-pld-linux-gcc -ggdb -O2 -Wall  -Wl,--as-needed -o test-source-selector  test-source-selector.o libedataserverui-1.2.la ../libedataserver/libedataserver-1.2.la -pthread -lglade-2.0 [...many -l libraries...] 
+ /bin/sh ../libtool --tag=CC --mode=link x86_64-pld-linux-gcc -ggdb -O2 -Wall  -Wl,--as-needed -o test-source-selector  test-source-selector.o libedataserverui-1.2.la ../libedataserver/libedataserver-1.2.la -pthread -lglade-2.0 [...many -l libraries...]
  -lgnome-keyring -lpthread
  
  x86_64-pld-linux-gcc -ggdb -O2 -Wall -Wl,--as-needed -o .libs/test-source-selector test-source-selector.o -pthread ./.libs/libedataserverui-1.2.so [many, many .so and -l libraries] -lpthread
@@ -288, +288 @@

  
  
  === 3. unresolved symbols caused by incorrect order ===
- Two of most difficult of common problems at once, 
+ Two of most difficult of common problems at once,
  [http://cvs.pld-linux.org/cgi-bin/cvsweb/SPECS/evolution.spec?rev=HEAD evolution.spec]:
  
  The difficulties are: