[CentOS] GCC 4.9 in CentOS 7 ??

[Alice Wonder]

On 02/07/2017 07:34 AM, Gordon Messmer wrote:
> On 02/07/2017 01:42 AM, Alice Wonder wrote:
>> The software collections looks like it might interfere with some of my
>> own packaging (repos that build upon EPEL to provide modern server
>> stack based on LibreSSL and a repo for modern multimedia)
>
>
> Where do you see a conflict?  Those packages are structured to avoid
> conflict with the base platform, but installing into an alternate root
> (/opt/rh/<package collection>) and are normally active only when
> specifically enabled in a login session. That is, they're available when
> wanted but don't affect the system when they aren't.
>

What I mean is conflicts in devel packages.

What I mean is this - my LibreSSL package installs in /usr and not in 
/opt and that is intentional, so that it is not possible to have both 
opennsl-devel and libressl-devel installed at the same time, since they 
both are the same API.

Here's why -

If I build php against LibreSSL but some some of the PHP build 
dependencies are built against OpenSSL then those build dependencies 
will want openssl-devel.

If both openssl-devel and libressl-devel are /usr then the packages will 
conflict and I know I have to rebuild the PHP build dependencies against 
LibreSSL before I can build PHP.

But if LibreSSL was in /opt then RPM would have no problem having both 
libressl-devel and openssl-devel installed at the same time, and the 
build of PHP could potentially result in mixed implementation of the 
OpenSSL API - e.g. PHP is linked against LibreSSL but also is linked 
against Net-SNMP which is linked against OpenSSL - so that the dynamic 
loader then loads two shared libraries that provide the same API.

That's what I am trying to avoid, and that is easiest to avoid by just 
using /usr as the prefix so that devel files have their headers in 
/usr/include and devel files for different implementations of the same 
API can not be installed at the same time.