[cknitt]

Fixes #8977.

This removes the leftovers the issue lists:

• .cmt code for the embedded .cmi. Cmi_format.output_cmi had no caller and is removed. The comment on create_cmi no longer says save_cmt calls it. cmt_interface_digest was always None and never read, so the field is removed; the .cmt magic number moves from T047 to T048 because the marshalled record changes. Cmt_format.read no longer tries to read a cmt after an embedded cmi, which the earlier magic bumps made unreachable, and the docs in cmt_format.mli/cmt_format_common.ml no longer promise that older layouts are read.
• Oprint.out_type_extension, and the Res_outcome_printer function that only set it, are removed.
• Ext_namespace.try_split_module_name, and its ounit case, are removed.
• Ast_untagged_variants.block_type_can_be_undefined is removed.
• The comment on Ast_helper.Jsx_component.take now says that the JSX transform takes a payload on a lone @react.componentWithProps with a deprecation warning (Accept a payload on @react.componentWithProps with a deprecation warning #8944) and rejects the other leftovers.
• Unused test inputs: tests/build_tests/regexp_statement_formatting/rescript.json, tests/build_tests/option_transitive_dependency/rescript.json (both tests run bsc with explicit flags) and rewatch-ocaml/tests/failure/Broken.invalid (only Broken.fixed is read).
• Older leftovers: the (*TODO: add +10*) in bsc_warnings.ml, which refers to a removed warning, and the empty compiler/bsc/rescript_compiler_main.mli.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Xk6AeCYpCK4SZRtHYKHGoe

[github-actions]

Semantic Diff

1 commit · Full page

Remove dead code, stale comments and unused test inputs

_{8427be4 · Christoph Knittel with Claude Opus 5.5 · Oct 23, 2026}

Why

Recent removals left definitions without callers, which no warning reports because they are exported or in a module without an interface: Cmi_format.output_cmi, the always-None cmt_interface_digest, the read of a cmt after an embedded cmi (unreachable since the magic bumps of #8805 and #8928), Oprint.out_type_extension, Ext_namespace.try_split_module_name and Ast_untagged_variants.block_type_can_be_undefined. Comments that promised older .cmt layouts, a JSX transform rejection that #8944 made a deprecation, and a TODO for a removed warning are corrected, and the empty rescript_compiler_main.mli and three unused test inputs removed.

Review

• Why does the cmt magic number change? Removing cmt_interface_digest changes the marshalled cmt_infos record, so .cmt files of the previous layout must be rejected rather than misread: T047 becomes T048.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.24%. Comparing base (9e2f371) to head (8427be4).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8991      +/-   ##
==========================================
+ Coverage   81.22%   81.24%   +0.01%     
==========================================
  Files         457      457              
  Lines       63862    63833      -29     
==========================================
- Hits        51875    51862      -13     
+ Misses      11987    11971      -16     

Files with missing lines	Coverage Δ
compiler/ext/config.ml	100.00% <ø> (ø)
compiler/ext/ext_namespace.ml	90.90% <ø> (-1.40%)	⬇️
compiler/ml/ast_helper.ml	88.21% <ø> (ø)
compiler/ml/ast_untagged_variants.ml	88.09% <ø> (+0.88%)	⬆️
compiler/ml/cmi_format.ml	75.55% <ø> (+10.17%)	⬆️
compiler/ml/cmt_format_common.ml	81.81% <100.00%> (+4.76%)	⬆️
compiler/ml/oprint.ml	0.00% <ø> (ø)
compiler/syntax/src/res_outcome_printer.ml	81.83% <ø> (+0.36%)	⬆️
tests/ounit_tests/ounit_string_tests.ml	93.24% <ø> (-0.31%)	⬇️

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commit: 8427be4

[github-actions]

Developer playground preview: https://rescript-lang.github.io/rescript/dev-playground/?version=pr-8991

[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 2026-10-23T09:27:33.388864Z	8427be4	Manual request

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. You're on a roll.

Reviewed commit: 8427be4c96

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