This is in reference to email from Daniel Weber <DaWeber@harmanbecker.com>
on the Jamming mailing list.  The Jamfile tree here emulates his
and prints SUBDIR_TOKENS for each directory.  See the bottom of this
file for a copy of the email.

The problem as posed is essentially that the SUBDIR_TOKENS are not
set correctly when you SubInclude a Jamfile whose SubDir is not
a direct child of of the SubIncluding Jamfile, and whose TOP is
not the same as the including Jamfile.

The result of his fix is that the SUBDIR_TOKENS, etc are set as
relative to the including Jamfile's root when jam is called from
the including tree, and as relative to its own TOP when jam is
called from within the sub tree in which the included Jamfile
resides.

I'm not sure if this is correct behavior - my initial response is
that I would expect the SUBDIR_TOKENS, etc. to be relative to the
TOP most recently set by a call to SubDir.  This seems like the
most straightforward and modular possibility - a given Jam project
would have the same behavior regardless of whether it is being
compiled on its own or as a sub-part of a larger project. 
Nevertheless,  the behavior Mr. Weber describes is clearly wrong
so I'm integrating his fix.


----------------------- Email follows ---------------------------

[jamming] Bug in SubDir rule?
Date: Wed, 4 Aug 2004 18:35:42 +0200
From: "Weber, Daniel" <DaWeber@harmanbecker.com>
To: <jamming@perforce.com>
Hi,

Iīve encountered a problem using SubDir. Given the following hierarchy:
 
root
 |
 |-Jamfile
 |
 |--test
    |
    |-Jamfile
    |
    |--foo
       |
       |-Jamfile
 
and the two "lower" Jamfiles looking like this:
 
test/foo/Jamfile:
  SubDir TEST foo ;
 
test/Jamfile:
  SubDir TEST
  SubInclude TEST foo ;
 
If the root Jamfile now contains the following statements:

  SubDir ROOT ;
  SubInclude ROOT test ;

everything is just fine, but if is looks like this:

  SubDir ROOT ;
  SubInclude ROOT test foo ;
 
i.e. skipping the test directory and itīs implicit definition of TEST,
jamīs subdir variables are set to wrong values, e.g. SUBDIR_TOKENS
contains only "test" instead of being "test foo".
 
The problem seems to be the following line in the SubDir rule:

   SUBDIR_DOWN = $($(_top)-DOWN) $(_tokens) ;

where the _tokens have already been altered before in that special case. 
When replacing it with

   SUBDIR_DOWN = $($(_top)-DOWN) $(<[2-]) ;

everything seems to be OK.

I must admit weīve altered and extended the default Jambase, but this part 
of it is the same as in jam2.5rc2.

Greetings
Daniel