PATCH: Run V3 tests on installed compiler

[Mark Mitchell]

Mike Stump wrote:

> I have a preference for reading testsuite_files, if it exists.  

I *think* Benjamin's already decided not to go that route, but I'll do 
whatever is requested.

> Also,  I 
> don't think it is unreasonable for the testsuite to build by  default 
> the objects it needs during the build, and then just using  them if they 
> like that workflow.  The difference can be put into the  site.exp file, 
> such as:
> 
>     set TESTING_IN_BUILD_TREE 1
> 
> and then that can be checked; simple, quick, efficient, clear.

I think that's a mistake.

I think it's a desirable invariant to have the two testing methods (in 
the build tree, and in the installed tree) as similar as possible.  With 
TESTING_IN_BUILD_TREE, I think we're very likely to (a) consistently 
break testing in the installed tree, when we update only part of some 
conditional, or forget about it, and (b) have hard-to-explain 
differences in results between the two approaches.  We also have to 
maintain the build logic for the secondary objects in two places: (a) 
Makefiles, for use in the build tree, and (b) DejaGNU, for use in 
isntalled tree.

Obviously, there are essential differences for testing in the build 
tree, in that compiler paths are different, -B/-L options are required, 
etc. -- but I'd like to see us keep the set of differences as small as 
reasonably possible.

-- 
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304