Fix soundness bug with clone overrides of subtypes#1062
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Pull request overview
This PR strengthens theory cloning soundness by rejecting subtype overrides that would otherwise allow cloning theories into inconsistent environments (potentially enabling contradictions).
Changes:
- Adds a regression test that demonstrates an invalid subtype override during
clone. - Extends cloning incompatibility reporting with subtype-specific incompatibility reasons (carrier type / predicate).
- Implements subtype-compatibility checks during theory replay when overriding subtype-declared types.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| tests/subtype-override.ec | New regression test ensuring invalid subtype overrides fail during cloning. |
| src/ecUserMessages.ml | Adds user-facing error messages for subtype-specific incompatibilities. |
| src/ecTheoryReplay.ml | Adds subtype compatibility checks and attempts to preserve subtype metadata across type overrides. |
| src/ecThCloning.mli | Extends incompatible with subtype-specific variants. |
| src/ecThCloning.ml | Mirrors the incompatible type extensions in the implementation. |
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…pe with compatible base type and predicate
strub
approved these changes
Jul 8, 2026
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Emit error when overriding a subtype with a type that is not a subtype with compatible base type and predicate. See the added test for why this is a problem. The gist is that you could obtain theories with two sets of lemmas that are incompatible with each other, leading to contradictions.