Linking static libraries to other static libraries

Question

I have a small piece of code that depends on many static libraries  a 1-a n   I d like to package up that code in a static library and make it available to other people    My static library  lets call it X  compiles fine   I ve created a simple sample program that uses a function from X  but when I try to link it to  X  I get many errors about missing symbols from libraries a 1 - a n   Is there a way that I can create a new static library  Y that contains X and all the functionality needed by X  selected bits from a 1 - a n   so that I can distribute just Y for people to link their programs to     UPDATE   I ve looked at just dumping everything with ar and making one mega-lib  however  that ends up including a lot of symbols that are not needed  all the  o files are about 700 MB  however  a statically linked executable is 7 MB   Is there a nice way to include only what is actually needed     This looks closely related to How to combine several C C   libraries into one

User · Answer

Alternatively to Link Library Dependencies in project properties there is another way to link libraries in Visual Studio    Open the project of the library  X  that you want to be combined with other libraries  Add the other libraries you want combined with X  Right Click  Add Existing Item      Go to their properties and make sure Item Type is Library   This will include the other libraries in X as if you ran  lib  out X lib X lib other1 lib other2 lib

User · Answer

On Linux or MingW  with GNU toolchain   ar -M  lt  lt EOM     CREATE libab a     ADDLIB liba a     ADDLIB libb a     SAVE     END EOM ranlib libab a   Of if you do not delete liba a and libb a  you can make a  thin archive    ar crsT libab a liba a libb a   On Windows  with MSVC toolchain   lib exe  OUT libab lib liba lib libb lib

User · Answer

Note before you read the rest  The shell script shown here is certainly not safe to use and well tested  Use at your own risk   I wrote a bash script to accomplish that task  Suppose your library is lib1 and the one you need to include some symbols from is lib2  The script now runs in a loop  where it first checks which undefined symbols from lib1 can be found in lib2  It then extracts the corresponding object files from lib2 with ar  renames them a bit  and puts them into lib1  Now there may be more missing symbols  because the stuff you included from lib2 needs other stuff from lib2  which we haven t included yet  so the loop needs to run again  If after some passes of the loop there are no changes anymore  i e  no object files from lib2 added to lib1  the loop can stop    Note  that the included symbols are still reported as undefined by nm  so I m keeping track of the object files  that were added to lib1  themselves  in order to determine whether the loop can be stopped       bin bash  lib1   1  lib2   2   if     -e  lib1 backup    then     echo backing up     cp  lib1  lib1 backup fi  remove later     new tmp file         file   mktemp      remove later   remove later  file      eval  1  file   remove tmp files         rm  remove later   trap remove tmp files EXIT  find symbols         nm  1  2   cut -c20-   sort   uniq     new tmp file lib2symbols new tmp file currsymbols  nm  lib2 -s --defined-only  gt   lib2symbols  prefix  xyz import   pass 0 while true  do       pass         echo  Starting pass   pass      curr  lib1     find symbols  curr  --undefined-only   gt   currsymbols     changed 0     for sym in   cat  currsymbols   do         for obj in   egrep    sym in     o   lib2symbols   cut -d    -f3   do             echo    Found  sym in  obj               if   -e   prefix obj     then continue  fi             echo      - gt  Adding  obj to  lib1              ar x  lib2  obj             mv  obj   prefix obj              ar -r -s  lib1   prefix obj              remove later   remove later  prefix obj                changed changed 1           done     done     echo  Found  changed changes in pass   pass       if     changed    0     then break  fi done   I named that script libcomp  so you can call it then e g  with    libcomp libmylib a libwhatever a   where libwhatever is where you want to include symbols from  However  I think it s safest to copy everything into a separate directory first  I wouldn t trust my script so much  however  it worked for me  I could include libgsl a into my numerics library with that and leave out that -lgsl compiler switch

User · Answer

If you are using Visual Studio then yes  you can do this   The library builder tool that comes with Visual Studio allows you to join libraries together on the command line   I don t know of any way to do this in the visual editor though   lib exe  OUT compositelib lib  lib1 lib lib2 lib

User · Answer

A static library is just an archive of  o object files  Extract them with ar  assuming Unix  and pack them back into one big library

User · Answer

Static libraries do not link with other static libraries  The only way to do this is to use your librarian archiver tool  for example ar on Linux  to create  a single new static library by concatenating the multiple libraries   Edit  In response to your update  the only way I know to select only the symbols that are required is to manually create the library from the subset of the  o files that contain them  This is difficult  time consuming and error prone  I m not aware of any tools to help do this  not to say they don t exist   but it would make quite an interesting project to produce one

[c++] Linking static libraries to other static libraries

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