| commit | 323e009c757229bdf58f68fde1c5bf07e9e65b61 | [log] [tgz] |
|---|---|---|
| author | Robert Findley <rfindley@google.com> | Fri Oct 15 16:39:39 2021 -0400 |
| committer | Robert Findley <rfindley@google.com> | Mon Oct 18 22:55:32 2021 +0000 |
| tree | 3132a1fe9c4d8bdd004e5f5d8a979f6796268fac | |
| parent | 73971784dc586a5db3b81dfdd41954f650d493ac [diff] |
go/types: ensure named types are expanded after type-checking Rather than using Checker.later in newNamed, add a Checker.defTypes field to track named types that have been created during type-checking, and use this to expand named types as a final phase in type checking. We have encountered several bugs related to infinite recursion while expanding named types, because (I would argue) we have two conflicting requirements in the type checker: ensuring that we eventually collapse underlying chains, and yet allowing lazy substitution of the underlying type in instances. The former is necessary for correctness, and to ensure that we detect cycles during the type-checking pass. The latter is necessary to allow infinitely expanding patterns of instances through underlying or method definitions. I believe this CL reconciles these conflicting requirements, by creating a boundary between types that are encountered in the source during type checking, and instances that are created by recursive evaluation. At the end of the type checking pass, Checker.defTypes should contain all possible origin types for instantiation. Once we compute the true underlying for these origin types, any remaining instances that are unresolved are guaranteed to have an origin with a valid underlying. Therefore, we can return from the type-checking pass without calling under() for these remaining instances. Fixes #48703 Fixes #48974 Change-Id: I1474f514e2ab71c1ad4c3704fe32bfba11d59394 Reviewed-on: https://go-review.googlesource.com/c/go/+/356490 Trust: Robert Findley <rfindley@google.com> Run-TryBot: Robert Findley <rfindley@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
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