[Backport releases/v4.29.0] fix: mark auxiliary definitions from normalizeInstance as meta#13044
Open
github-actions[bot] wants to merge 2 commits intoreleases/v4.29.0from
Open
[Backport releases/v4.29.0] fix: mark auxiliary definitions from normalizeInstance as meta#13044github-actions[bot] wants to merge 2 commits intoreleases/v4.29.0from
normalizeInstance as meta#13044github-actions[bot] wants to merge 2 commits intoreleases/v4.29.0from
Conversation
This PR adjusts the results of `inferInstanceAs` and the `def` `deriving` handler to conform to recently strengthened restrictions on reducibility. This change ensures that when deriving or inferring an instance for a semireducible type definition, the definition's RHS is not leaked when the instance is reduced at lower than semireducible transparency. More specifically, given the "source type" and "target type" (the given and expected type for `inferInstanceAs`, the right-hand side and applied left-hand side of the `def` for `deriving`), we synthesize an instance for the source type and then unfold and rewrap its components (fields, nested instances) as necessary to make them compatible with the target type. The individual steps are represented by the following options, which all default to enabled and can be disabled to help with porting: - `backward.inferInstanceAs.wrap`: master switch for instance adjustment in both `inferInstanceAs` and the default `deriving` handler - `backward.inferInstanceAs.wrap.reuseSubInstances`: reuse existing instances for the target type for sub-instance fields to avoid non-defeq instance diamonds - `backward.inferInstanceAs.wrap.instances`: wrap non-reducible instances in auxiliary definitions - `backward.inferInstanceAs.wrap.data`: wrap data fields in auxiliary definitions (proof fields are always wrapped) This PR is an extension and rewrite of prior work in Mathlib: leanprover-community/mathlib4#36420 Last(?) part of fix for #9077 🤖 Prepared with Claude Code Proofs that relied on the prior "defeq abuse" of these instance or that depended on their specific structure may need adjustments. As `inferInstanceAs A` now needs to know the source and target types exactly before it can continue, it cannot be used anymore as a synonym for `(inferInstance : A)`, use the latter instead when source and target type are identical.
…13043) This PR fixes a bug where `inferInstanceAs` and the default `deriving` handler, when used inside a `meta section`, would create auxiliary definitions (via `normalizeInstance`) that were not marked as `meta`. This caused the compiler to reject the parent `meta` definition with: ``` Invalid `meta` definition `instEmptyCollectionNamePrefixRel`, `instEmptyCollectionNamePrefixRel._aux_1` not marked `meta` ``` The fix adds an `isMeta` parameter to `normalizeInstance` that is propagated from the elaboration context (`isMarkedMeta` for `inferInstanceAs`, `Scope.isMeta` for the deriving handler), and marks each auxiliary definition created by `mkAuxDefinition` as `meta` when appropriate. Found while adapting Mathlib to #12897. 🤖 Prepared with Claude Code Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com> (cherry picked from commit 8ae3963)
kim-em
force-pushed
the
releases/v4.29.0
branch
from
96a2343 to
d7ebdca
Compare
kim-em
requested review from
TwoFX,
hargoniX,
leodemoura and
tydeu
as code owners
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Backport 8ae3963 from #13043.