tree a2d932a4cacdbb36e7c7a04aaad184b570221ef2
parent f0d1fa4e9377ef2102ce48f29d167af9fd75b327
author Marcel van Lohuizen <mpvl@golang.org> 1612603863 +0100
committer Marcel van Lohuizen <mpvl@golang.org> 1612622594 +0000

internal/core/adt: "fix" disjunction resolution

The recent performance improvement eliminated disjuncts
too aggressively, causing some disjuncts to disappear.
Early elimination prevents exponential blowup, but of course
it should not make it incorrect.

Note that for most common uses, like protobuf and K8s
structs with discriminator fields, special optimizations exist
that make this linear. But this has not been implemented yet.

Now this fix exposed another bug. This bug was deliberate to
work around a limitation of default values when representing
oneOf fields. We planned to introduce a "required field" annotation
which would also allow to represent these kind of semantics
much more elegantly.

For now, though, we are stuck in a position that more than one
oneOf field cannot be represented properly with defaults.
We fix it for now in an even more AWFUL way, and instead work
towards a proper solution based on required fields.

Issue #726

Change-Id: Id4bcd0445612e12fba48a744654de4e1852c552e
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/8641
Reviewed-by: Paul Jolly <paul@myitcv.org.uk>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>