[cknitt]

Part of #9074.

Behavioural tests for OCaml-derived features that had little or no coverage:

• gadt_test: a typed evaluator, type witnesses with refined matches, an equality witness, existentials (record, tuple and first-class module payloads), a typed printf, GADTs with @as, @tag and @unboxed, and polymorphic recursion.
• advanced_types_test: polymorphic record fields, explicit polymorphic annotations, constraint, as 'a, #...t patterns, private types, variance, destructive substitution, with module, module type of, higher-order and generative functors, and typed first-class modules.
• extensible_variant_test: inline records with @as, rebinding, indexed extensions, private extensible types, and generative local exceptions.
• Two error-message fixtures: matching a GADT without a locally abstract type, and polymorphic recursion without an annotation.

Fixtures for the bugs found are added by the PRs that fix them.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Kbf3gLMawVgtmiKy3TMBc3

[github-actions]

Changelog

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Semantic Diff

1 commit · Full page

✏️ Test GADTs and other OCaml-derived type and module features

_{09be8ce · cknitt + Claude · Oct 27, 2026, 12:39 UTC · edited}

GADTs, existentials, polymorphic record fields, constraint, private and indexed extensible types, destructive substitution and typed first-class modules had no behavioural tests. Part of #9074.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.69%. Comparing base (799a82f) to head (09be8ce).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9076      +/-   ##
==========================================
+ Coverage   81.48%   81.69%   +0.20%     
==========================================
  Files         460      460              
  Lines       64728    64728              
==========================================
+ Hits        52744    52879     +135     
+ Misses      11984    11849     -135     

see 14 files with indirect coverage changes

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commit: 09be8ce

[github-actions]

Developer playground preview: https://rescript-lang.github.io/rescript/dev-playground/?version=pr-9076

[cknitt]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-27T14:21:58.043087Z	3b48492	Manual request

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Hooray!

Reviewed commit: 3b48492446

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[cristianoc]

Looks good to me. Thanks for the changes.