Statically linking in a static library

Statically linking in a static library

[Anthony Weston]

Hi,

I'm having trouble with statically linking.  I've created a static
library that statically links to other static libraries.  My hope by
doing this was so other users would only need to include one static
library when linking in their executable.  However when I nm the
created the static library all the references are unresolved.  Is
there an argument that will force the linker to resolve these symbols?

Example:

libA.a defines functionA.
libB.a defines functionB.

I create libC.a which statically links and uses both libA.a and libB.a.

When running nm libC.a the results show that neither functionA nor
functionB can be resolved so libA.a and libB.a also need to be
statically linked into the final executable.

Thank you,
Tony

Re: Statically linking in a static library

[Ian Lance Taylor]

Anthony Weston <tony.weston@veliosystems.com> writes:

> I'm having trouble with statically linking.  I've created a static
> library that statically links to other static libraries.  My hope by
> doing this was so other users would only need to include one static
> library when linking in their executable.  However when I nm the
> created the static library all the references are unresolved.  Is
> there an argument that will force the linker to resolve these symbols?
>
> Example:
>
> libA.a defines functionA.
> libB.a defines functionB.
>
> I create libC.a which statically links and uses both libA.a and libB.a.
>
> When running nm libC.a the results show that neither functionA nor
> functionB can be resolved so libA.a and libB.a also need to be
> statically linked into the final executable.

Yes, that is how Unix linkers work.

If you want the final program to be able to only link against a single
library, then you will need to incorporate libA.a and libB.a into
libC.a.  E.g., do something along the lines of

ar x libA.a
ar x libB.a
ar rc libC.a *.o

Ian

Re: Statically linking in a static library

[Joel Dice]

On Mon, 19 Dec 2011, Ian Lance Taylor wrote:

> Anthony Weston <tony.weston@veliosystems.com> writes:
>
>> I'm having trouble with statically linking.  I've created a static
>> library that statically links to other static libraries.  My hope by
>> doing this was so other users would only need to include one static
>> library when linking in their executable.  However when I nm the
>> created the static library all the references are unresolved.  Is
>> there an argument that will force the linker to resolve these symbols?
>>
>> Example:
>>
>> libA.a defines functionA.
>> libB.a defines functionB.
>>
>> I create libC.a which statically links and uses both libA.a and libB.a.
>>
>> When running nm libC.a the results show that neither functionA nor
>> functionB can be resolved so libA.a and libB.a also need to be
>> statically linked into the final executable.
>
> Yes, that is how Unix linkers work.
>
> If you want the final program to be able to only link against a single
> library, then you will need to incorporate libA.a and libB.a into
> libC.a.  E.g., do something along the lines of
>
> ar x libA.a
> ar x libB.a
> ar rc libC.a *.o

Be careful, though, about files with the same name (e.g. myobject.o in 
both libA.a and libB.a).  If they're really the same file, it won't matter 
which one you include, but if they're different, you may need to rename 
one so they're both included.