BIRD 2.0.5 build failures on RHEL/CentOS 6 and 7

[Robert Scheck]

Hello Ondrej,

On Mon, 05 Aug 2019, Ondrej Zajicek wrote:
> I think we started to require newer bison (although it should be checked
> by configure and complained there). We aim to be compatible with 5 year
> old systems, but RHEL/CentOS 6 is too old even for that.

while this is a good pointer indeed, it's unfortunately wrong. Using bison
3.0.4 (same version like RHEL/CentOS 7 uses) still leads to the same error.

But following your pointer in general, I figured out that GCC 4.4.x causes
the error, while GCC 4.8.x works. Looks like BIRD depends on a feature from
GCC 4.5 (or newer, I didn't track this down further). Thanks though!

> Not sure about that, it works on CentOS 7 in our Gitlab test build.
> 
> It seems like our configure script improperly adds -flto even if CFLAGS /
> LDFLAGS are expliclty set, and it is incompatible with your flags.

Sounds like a bug in the configure script then, may you have a look to it,
please?


Regards,
  Robert