[Boost-build] Proposal to extend gcc's flavor feature

From: Roland Schwarz (roland.schwarz_at_[hidden])
Date: 2008-04-21 13:12:56

Currently it is hard to condition on a specific
incarnation of gcc.

While it is possible to condition on a certain
version of gcc, this still is unreliable, since
the version is, what the user specifies in
user-config.jam.

A special subfeature named <flavor> exists, mainly
to disambiguate between mingw and "normal" gcc's.

The flavor still has it's shortcoming though, since
if not explicitly requested, it will get the value
of the first configured gcc. This most likely will
come to a surprise of the user.

Since the flavor is just a special case of
-dumpmachine I suggest making flavor more general,
i.e. make flavor the string that is returned by
-dumpmachine for all gcc's.

Benefits:
  The incarnation of gcc can be uniquely referenced,
  which is of particular importance in cross builds.
  (Where mingw/cygwin is only a special case.)

  It is mostly compatible, i.e. the lib tagging
  continues to work as current.

Drawbacks:
  The directory names are getting longer, since flavor
  is a non-incidental feature.

Is there a way to make the feature assymetric, so that
the default gcc would not suffer from the longer names?

I attach a diff to current gcc.jam to this mail.

I am interested to hear what you think about this proposal.

Regards,
Roland

-- 
_________________________________________
  _  _  | Roland Schwarz
 |_)(_  | aka. speedsnail
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