Re: Why does libca.so depend on libreadline.so?

[Han Lee via Tech-talk <tech-talk at aps.anl.gov>]

Hi Dmitry,

I think the head file (especially comments in the file) may be what you are interested in to get your understanding.

https://github.com/epics-base/epics-base/blob/7.0/modules/libcom/src/osi/epicsReadline.h

From my naive understanding, it is required for an iocsh functionality. 

Best,

Han

On Mon, May 8, 2023 at 9:46 PM Dmitry Yu. Bolkhovityanov via Tech-talk <tech-talk at aps.anl.gov> wrote:

Michael,

On Sun, 7 May 2023, Michael Davidsaver wrote:

> On 5/6/23 23:12, Dmitry Yu. Bolkhovityanov via Tech-talk wrote:
>>  P.S. Yes, I'm aware of a "COMMANDLINE_LIBRARY=EPICS" flag (which took some
>>  time to figure out :D), but the question remains -- why any commandline
>>  editing is needed for network communication libraries at all?
>
> This is a side-effect of the convention we use to support both dynamic and
> static linking
> with one configuration.  Since static libraries do not carry dependency
> information, when
> linking statically it is necessary to give a complete list of all dependent
> libraries
> when linking any executable.  This includes libreadline when libCom depends
> on it.
>
> One simple way to avoid this over-linking in the dynamic case by passing
> "-Wl,--as-needed"
> when linking.
>
> (assumes GCC or clang on an ELF target)

Thanks for this -- I didn't know of this linker option!

However, I still don't understand: why libCom depends on libreadline (or
any commandline-editing library)?


With best regards,
Dmitry

--

Jeong Han Lee, Dr.rer.nat.

Staff Scientist and Engineer

Cell: +1 510 384 3868

https://orcid.org/0000-0002-1699-2660