Re: Ada subtypes and base types

[Andrew Haley <aph at redhat dot com>]

Jeffrey A Law writes:
 > On Wed, 2006-03-29 at 14:28 -0700, Tom Tromey wrote:
 > 
 > > On irc today we were discussing handling 'this' in gcj.  We can add an
 > > attribute to the argument to mark it as non-null... but strangely
 > > there doesn't seem to be a way to mark other local variables as
 > > known-non-null -- a curious deficiency.
 > It seems to me that for other locals that the non-null property
 > ought to be a property of how those locals are assigned a value.
 > ie, if we're going to be able to derive a non-null for a local we
 > should be able to derive it from the RHS of the assignment(s) to
 > that local.

Right, that's true.  The idea is that a great many library functions
either return a valid object or throw an execption, and we can
propagate that information to VRP>

 > IIRC "this" is actually a parameter and thus there's no assignment
 > we can derive information from.

Mmm, yeah.  The point is that we solved the problem for "this", but
not for other things.

Andrew.