[Buildroot] [PATCH 1/1] package/capnproto: add openssl optional dependency

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

On Sun, 9 Aug 2020 18:52:15 +0200
"Yann E. MORIN" <yann.morin.1998@free.fr> wrote:

> So, I got the answer, at least partially:
> 
>   - the code snippet above is only executed when auto-detection is done
> 
>     - before this patch, it would alwasys fail in static builds, so
>       capnproto would always be built without ssl/tls support, and a
>       shared build would depend on the build ordering;
> 
>     - with this patch, we explicitly enable or disable openssl support,
>       so the code snippet is not executed.
> 
>   - the dependency on openssl is only used to build a library, that is
>     not used to link an executable in capnproto, and does not seem to be
>     used by of our in-tree packages that use capnproto.
> 
> And indeed, the link forget -lz )indentation mine):
> 
>     /bin/bash ./libtool --tag=CXX \
>         --mode=link /home/ymorin/dev/buildroot/O/host/bin/arm-linux-g++ \
>         [...] \
>         -DKJ_HAS_OPENSSL \
>         -o libkj-tls.la \
>         [...] \
>         -lssl -lcrypto -latomic
> 
> so indeed, no -lz.
> 
> Furthermre, capnproto does install a bunch of .pc file, but installs
> none for libkj-tls. And none of the .pc files insalled ever reference
> libkj-tls or ssl or crypto.
> 
> That's why we have no build failure in our autobuilders.
> 
> Yet, I wonder how openssl support works in capnproto, and if this patch
> ever makes sense in the context of Buildroot...

Thanks for the exhaustive research! I think we should not only look at
packages that are in Buildroot: people may be having their own custom
stuff that links against libkj-tls, so overall I think the patch makes
sense. There is something that optionally links against OpenSSL in
capnproto, so we should have an optional dependency on OpenSSL.

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com