Dafny's new auto-trigger feature is quite useful, but it leaves out a useful case: forall statements. In the attached file, no trigger is generated for the forall statement, even though there's a fairly obvious trigger (IsLessThanSuccessor(i)).
It would be nice if the auto-trigger feature could also work on forall statements. I had a more complicated instance in real code where a lemma's verification was timing out with no explanation as to why, and it was only via the axiom profiler that I learned it was due to a forall statement with no triggers.
predicate IsLessThanSuccesor(i:int)
{
i < i + 1
}
lemma LemmaWithoutTriggerOnForallStatement()
{
forall i
ensures IsLessThanSuccesor(i);
{
}
}
Comments: Sorry for the delay; indeed, this wasn't implemented because the generation happens too late in the pipeline. I too think it would be good to move it to the resolver (in fact to a rewriting pass).
It would be nice if the auto-trigger feature could also work on forall statements. I had a more complicated instance in real code where a lemma's verification was timing out with no explanation as to why, and it was only via the axiom profiler that I learned it was due to a forall statement with no triggers.
predicate IsLessThanSuccesor(i:int)
{
i < i + 1
}
lemma LemmaWithoutTriggerOnForallStatement()
{
forall i
ensures IsLessThanSuccesor(i);
{
}
}
Comments: Sorry for the delay; indeed, this wasn't implemented because the generation happens too late in the pipeline. I too think it would be good to move it to the resolver (in fact to a rewriting pass).