Re: Fixing the interpretation of $srcdir in DejaGnu

[Jacob Bachmeyer]

Ben Elliston wrote:
> On Wed, Nov 21, 2018 at 10:33:04PM -0600, Jacob Bachmeyer wrote:
>   
> > As part of the ongoing efforts to improve Automake integration, [...]
> >     
> Can you please elaborate on what you mean by Automake integration in
> this context?  To my mind, the Dejagnu Makefile and testsuite should
> use the standard Automake hooks for DejaGnu testsuites as much as
> possible. Looking at Makefile.am, it doesn't seem like there's a lot
> of bad hacks there?
>   

This is the ongoing issue of site.exp.  (That there are both local and 
global "site.exp" files adds confusion.)  Automake generates a site.exp 
that sets srcdir to @srcdir@ and the DejaGnu testsuite overrides that in 
RUNTESTDEFAULTFLAGS.  Needing to specify RUNTESTDEFAULTFLAGS is the 
hack, since it reveals a mismatch between Automake's $srcdir and 
DejaGnu's $srcdir, but those variables should have the same meaning as I 
thought had been confirmed in 
<URL:http://lists.gnu.org/archive/html/bug-dejagnu/2018-11/msg00007.html>.  
Do I misunderstand?

The problem is that overriding srcdir on the command line has 
limitations if site.exp also sets srcdir.  In particular, there is an 
interval between loading site.exp and parsing the command line for the 
second time.  During this time, DejaGnu loads the various configuration 
files (and its own libraries) using values from configuration files 
before restoring settings from the command line.

Automake sets @srcdir@ to the directory containing testsuite/ which is 
the "tool's source directory".  The DejaGnu testsuite overrides 
RUNTESTDEFAULTFLAGS to add "--srcdir $(srcdir)/testsuite" which caused 
problems with locating the tool init files and is ugly.  Interestingly, 
if DejaGnu used recursive make and I understand the Automake manual 
correctly, the value of @srcdir@ would include testsuite/, if DejaGnu 
were to be run in @objdir@/testsuite.  However, the DejaGnu makefiles 
are simpler than that and the DejaGnu testsuite is run at top-level in 
the build tree, so @srcdir@ is the top-level source directory when the 
testsuite is run.

Once this is fixed and DejaGnu uses Automake's value of $srcdir, there 
will no longer be a need to specify RUNTEST on the runtest command line 
either:  it can default to ${srcdir}/runtest in 
testsuite/lib/runtest.exp.  (And I will need to add documenting the two 
primary options for running DejaGnu -- at top-level or in the top 
testsuite/ directory -- to my local TODO list.  There is a third option, 
of course:  specify all of srcdir, objdir, and outdir, either on the 
command line or in ./site.exp (or, more precisely, "the local init 
file") in whatever directory DejaGnu is started.)


-- Jacob