semantic action failures

[psiha]

When executing a semantic action I can, well, find a semantic error in the input (e.g. a thing referenced by the input does not exist while the input itself is syntactically correct) - in which case I'd like to throw an error and have the same builtin mechanism as for expectations catch and handle it (i.e. where the input location/context information is still available)...
(currently I 'hack' this by throwing parse_error exceptions)

[tzlaine]

I don't consider that a hack. That sounds like a completely reasonable way to do what you want. Actions already have a built-in failure mechanism -- you just do pass_(ctx) = false. I'm not getting what the feature is that you're requesting.