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

[Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov>]

On 5/12/23 07:09, Simon Rose via Tech-talk wrote:
> Hi Dmitry -
>
> I do not get the same results as you. When I build various version of EPICS base (e.g. 7.0.4, 7.0.5) for linux-x86_64, libCom also depends on readline at that point. I don't think the change that Michael linked is the source of this dependency.
I guess my attempt to clarify has had the opposite effect...

libCom has long had an _optional_ dependency on libreadline (dating back to 2000 at the latest).

As has been said, this dependency can be bypassed when building epics-base by setting
"COMMANDLINE_LIBRARY = EPICS" in appropriate places under configure/

> git grep 'COMMANDLINE_LIBRARY\s*=' -- configure/
... will find many examples.

Historically, this dependency was often not enabled by default because initially there was no
attempt to automatically detect the presence of "readline.h".  Then at attempt was made with
$(wildcard in Makefile, which didn't work consistently.

My PR #254 changes the auto-detection scheme to use the __has_include() pre-processor feature
of newer C and C++ standards, which does a better job of finding readline.h.

https://github.com/epics-base/epics-base/pull/254