Re: GNAT and subunits

[stt@spock.camb.inmet.com (Tucker Taft)]

Robert Dewar (dewar@cs.nyu.edu) wrote:
: ...
: Now there are three options in the binder. Phil was apparently using the
: first, which is the default, and is what is used by gnatbl if you let
: gnatbl do the bind. I suspect that Phil wants to use the second or third.

: Option 1 (default). Use object files only (and ALI files). The binder 
: in this mode COMPLETELY IGNORES source files. So of course when Phil
: updated his subunit, and did a compilation to check its correctness which
: had no effect on the object files, then the binder did not notice and used
: the old objects without complaint. In this mode the binder merely checks
: that the objects it sees are self consistent version-wide, but it does not
: check that they are compatible with the source versions.

: Option 2 (-a) All source file mode. In this mode, the binder requires that
: (a) all sourrce files are present for all object files in the bind.
: (b) the source file versions are consistent with the versions referenced
: 	in the object files.

: Option 3 (-s) Sources if available. In this mode, the binder will find sources
: for whatever source files it can locate, and for this subset of sources, it
: will ensure consistency with the object files.

..

: P.P.S. In discussing these issues earlier today, we contemplated two
: features that might reduce the surrprise factor for people who don't
: read the documentation carefully:

:    1. If a parent unit is compiled with subunits missing, then revert
: 	automatically to -gnatc mode, complaining that "no code is
: 	generated because subunits are missing" or somesuch.

Sounds like a good idea.  You probably want to make it a warning instead
of an error, or else it will scare people.

:    2. Change the default of the binder to -s mode, we have been considering
: 	this for a while.

: I would particularly be interested in people's reactions to suggestion 2.

I think you should make the binder default "-s" to minimize the likelihood
of "pilot" error.  This also seems most compatible with the "conventional"
Ada library model.

-Tucker Taft   stt@inmet.com
Intermetrics, Inc.