[Fedora-packaging] arched BuildRequires?

[Michael Schwendt]

On Thu, 13 Jun 2013 22:44:53 +0200, Mattias Ellert wrote:

> tor 2013-06-13 klockan 19:20 +0200 skrev Björn Esser:
> 
> > What will break the spec by removing _isa-macro from BRs?  Is there any
> > PROVEN reason for this?  I'm NOT talking about the final-Requires in
> > spec.
> 
> It is VERY EASY to construct such an example.

Sure, that's the known corner-case for multiarch installations.

It's similar for any arch-conditional build requirements in spec files.
They are a bit of a hindrance, since one cannot rely on a downloaded
src.rpm's Requires being complete. Unless one rebuilds the src.rpm first
and then proceeds with the changed list of possibly arch-specific Requires
in the freshly built src.rpm (e.g. as Mock does it before fetching the
build requirements). Only then one can query the src.rpm with tools to
install a long list of needed builddeps.

> Consider a package containing the following BRs:
> 
> BuildRequires:	nss-devel >= 3.10
> BuildRequires:	openssl-devel
> BuildRequires:	cppunit-devel
> BuildRequires:	glibmm24-devel
> BuildRequires:	libdb-cxx-devel
> 
> All the BRs are satisfied:
> 
> $ rpm -q --whatprovides nss-devel openssl-devel cppunit-devel
> glibmm24-devel libdb-cxx-devel
> nss-devel-3.14.3-2.fc18.i686
> openssl-devel-1.0.1e-4.fc18.x86_64
> cppunit-devel-1.12.1-8.fc18.x86_64
> glibmm24-devel-2.34.1-1.fc18.x86_64
> libdb-cxx-devel-5.3.21-3.fc18.i686

Except for the minimum build environment, such as glibc-devel.i686 and
libstdc++-devel.i686, the compiler(s) and preprocessor(s). The build
would fail later on. %_isa in BRs here is like band-aid for a more
fundamental problem, and it adds even another problem.

Oh, btw, not even all -devel dependencies use %_isa yet. On a normal
x86_64 installation, installing something -devel.i686 often pulls in
x86_64 deps. For your example, nss-devel.i686 will do that, too.
%_isa would be needed in many many more places for multiarch operation.

> rpmbuild correctly detects the missing BRs:
> 
> error: Failed build dependencies:
> 	nss-devel(x86-64) >= 3.10 is needed by canl-c++-1.0.0-2.fc18.x86_64
> 	libdb-cxx-devel(x86-64) is needed by canl-c++-1.0.0-2.fc18.x86_64

Don't we prefer clean build environments, such as constructed by Mock?
I know some people use "setarch i686 rpmbuild ..." and "setarch i686 yum
...", which accesses the full i386 repos on x86_64 installations.

Conclusively, I understand what you like about %_isa in BR, but I think
it doesn't improve much compared with the confusion it adds.

-- 
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