[gentoo-dev] interest assay: eclass for stripping "modern" C[XX]FLAGS

[George Shapovalov <george@gentoo.org>]

Hi gang.

While working on getting ada related apps ready for use I stumbled upon the 
following issue. It happens that validated (read stable and verified as 
opposed to alpha-quality stuff in gcc-3.x tree) versions of gnat are based 
around older version of gcc, more specifically 2.8.1 (quite popular version 
amongst gcc-based compiler developers I might add). This means that when you 
will try to use your gcc-3.3 superoptimized set of  C[XX]FLAGS for emerging 
ada pakages you will get into trouble.
(Note that when you emerge gnat you merely get gcc-2.8.1 backend in addition 
to your existing versions. It goes into its own dir and does not even show up 
in gcc-config. Thus your regular gcc based emerges are not affected).

In order to go around this some flag stripping and mapping
(like -march={ pentium-mmx => i586  or  athlon-* => i686 })
has to be done in the eclass common to ada-related packages.
I highly suspect that this situation is not unique. I can myself name at least 
one more such package - gpc, which is so far mostly stable on gcc-2.95.3, 
although later alphas can be built with gcc-3.x.

Thus I would like to get an estimate on how usefull it will be to package code 
stripping "modern" C[XX]FLAGS to get them in conformance with the required 
version of gcc. I envision eclass that provides (say) versionize-flags 
function and takes a single argument - two major gcc version numbers (2.8, 
2.95 or 3.x) and strips "not yet recognized" flags accordingly.
Actually while I am on it, I think this function will be best fit into the 
existing flag-o-matic.eclass.

What does everybody thinks?

George



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