--export-dynamic question

--export-dynamic question

[Toon Knapen]

I would suspect the symbols defined in the static libraries that I link 
into my executable to appear in the final exe when the --export-dynamic 
option is passed on the command-line. However my findings proove 
otherwise (using redhat 8, ld version 2.13.90.02)

Using following files:

<begin foo.cpp>
int foo()
{ return 99 ; }
<end foo.cpp>

<begin main.cpp>
int main()
{ return 0 ; }
<end main.cpp>

I do:

gcc -c foo.cpp
gcc -c main.cpp
ld main.o foo.o

If I now 'nm a.out', I clearly see the function 'foo' in my a.out.

Now I first put the foo.o object-file into a library and then link the 
library into the exe like so:

ar ru libfoo.a foo.o
ld main.o libfoo.a

Now the function foo does not appear anymore when I 'nm a.out' (as 
expected since it is dead code)

Now however I link a.out using following command-line:

ld --export-dynamic main.o libfoo.a

And the funtion foo does not appear either (although I would expect the 
export-dynamic flag to prevent the dead-code elimination) ?

Thanks in advance,

Toon

Re: --export-dynamic question

[Paul Brook]

On Tuesday 31 August 2004 12:54, Toon Knapen wrote:
> ar ru libfoo.a foo.o
> ld main.o libfoo.a
>
> Now the function foo does not appear anymore when I 'nm a.out' (as
> expected since it is dead code)
>
> Now however I link a.out using following command-line:
>
> ld --export-dynamic main.o libfoo.a
>
> And the funtion foo does not appear either (although I would expect the
> export-dynamic flag to prevent the dead-code elimination) ?

Try --whole-archive.

Paul

Re: --export-dynamic question

[Andreas Schwab]

Toon Knapen <toon.knapen@fft.be> writes:

> Now however I link a.out using following command-line:
>
> ld --export-dynamic main.o libfoo.a
>
> And the funtion foo does not appear either (although I would expect the
> export-dynamic flag to prevent the dead-code elimination) ?

--export-dynamic does not change in any way how the linker collects input
files.  Since libfoo.a(foo.o) is not linked in you also don't get any
symbols defined in that file.  If you want to force linking in the whole
archive library use --whole-archive.

Andreas.

-- 
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