Circular project refenreces

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-10-15 04:36:21

When looking into the bug that Austin reported, I found that V2 behavious on 
circular project references is underspecified. Consider

project-root.jam
Jamfile
|
|
subdir
Jamfile

When bjam is executed in Jamfile, we need to load top-level Jamfile first, for 
example, to inherit attributes. The question is what happends if top-level 
Jamfile contains

1. "build-project subdir" ;
2. use-project /some_id : /subdir ;

With M8, both load "subdir/Jamfile" for a second time -- which is really bad. 
With my local fixes, the first case works ok. The second case, though, 
breaks.

The question: is this second case really necessary? I implicitly assumed that 
most times use-project will refer to projects with other project root. In 
this example, that "subdir" should contain a project-root.jam file.

Opinions?

- Volodya