Why does bison link with readline?

[Paul Smith]

Hi all;

Is there a reason that bison has -lreadline to the link line?  I cannot
find any code anywhere in the bison program that invokes readline() or
tests any preprocessor option specifying whether readline is linked.

I see that the bistromathic tool uses it, but that doesn't explain why
it's linked into the bison program.

Readline is really problematic because RedHat/CentOS 7 distributions
only ship libreadline.so.6, but Debian/Ubuntu distributions ship all
versions _EXCEPT_ 6 (they have packages for 5, 7, and 8).

I don't know why Debian/Ubuntu refuse to package readline 6 but it's
supremely annoying.

In any event the upshot is that you can't compile a single binary that
links readline (dynamically) and have it run without modification on
both these (very common) distributions.

If bison doesn't actually use readline can we just remove it from the
link line?

If bison does need to link readline for some reason, can you add a
--without-readline option to the configure script to explicitly disable
readline integration even when it seems to be available, so that we can
build portable binaries?

Thanks for your work on Bison!