Remove OCaml leftovers

[cknitt]

Removes OCaml leftovers that ReScript code can't produce or reach. Each commit removes one:

1. Warning numbers that no longer exist. The -warn-help descriptions still listed warnings 17, 18, 19, 25, 31, 36, 46, 55 and 59, which have no constructor anymore. The warning letters (c, k, l, m, s, v, x) and the defaults still pointed at removed numbers too: the default -w disabled 50, and the default -warn-error enabled 6. These are dropped from the descriptions, the letters, the defaults, the build schema, ERROR_VARIANTS.md and the dev playground's flags. No warning that can fire changes.
2. Record_float_unused. This record representation was OCaml's float-only record. It is never created, and every match on it was assert false. It wasn't the last constructor of record_representation, so removing it changes the binary layout of type declarations, and the .cmi and .cmt magic numbers are bumped.
3. The ns.braces attribute name. It is the pre-res name of res.braces. The v0 bridge still decoded it in PPX output, but nothing has produced it since the attribute was renamed.
4. Unused Ast_helper functions. Const.int32/int64/char/float, Typ/Pat/Exp/Mty/Mod.attr and Te.decl/rebind have no callers.

User-facing OCaml leftovers stay out of this PR: the l integer suffix, the predefined End_of_file exception and the ocaml.* attribute aliases. Doc attributes users can write (@ocaml.doc, @ns.doc) are also unchanged.

🤖 Generated with Claude Code

https://claude.ai/code/session_013ZYFYMu3AE9P1xFVCR34d1

[cknitt]

@codex review

[codecov]

Codecov Report

❌ Patch coverage is 22.22222% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.40%. Comparing base (bbac536) to head (a125d6a).

Files with missing lines	Patch %	Lines
compiler/ext/warnings.ml	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8805      +/-   ##
==========================================
+ Coverage   80.38%   80.40%   +0.02%     
==========================================
  Files         447      447              
  Lines       60999    60984      -15     
==========================================
+ Hits        49034    49036       +2     
+ Misses      11965    11948      -17     

Files with missing lines	Coverage Δ
compiler/gentype/translate_type_declarations.ml	89.51% <ø> (ø)
compiler/ml/ast_helper.ml	87.13% <ø> (+4.26%)	⬆️
compiler/ml/ast_mapper_from0.ml	76.62% <100.00%> (+0.25%)	⬆️
compiler/ml/matching.ml	77.24% <ø> (ø)
compiler/ml/printtyped.ml	0.00% <ø> (ø)
compiler/ml/rec_check.ml	46.95% <ø> (ø)
compiler/ml/translcore.ml	87.39% <ø> (ø)
compiler/ml/types.ml	71.05% <ø> (+1.82%)	⬆️
compiler/ext/warnings.ml	75.65% <0.00%> (ø)

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[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 2026-10-12T04:42:57.666867Z	4bff2f4	Manual request

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

[pkg-pr-new]

Open in StackBlitz

rescript

npm i https://pkg.pr.new/rescript@8805

@rescript/belt

npm i https://pkg.pr.new/@rescript/belt@8805

@rescript/darwin-arm64

npm i https://pkg.pr.new/@rescript/darwin-arm64@8805

@rescript/darwin-x64

npm i https://pkg.pr.new/@rescript/darwin-x64@8805

@rescript/linux-arm64

npm i https://pkg.pr.new/@rescript/linux-arm64@8805

@rescript/linux-x64

npm i https://pkg.pr.new/@rescript/linux-x64@8805

@rescript/runtime

npm i https://pkg.pr.new/@rescript/runtime@8805

@rescript/win32-x64

npm i https://pkg.pr.new/@rescript/win32-x64@8805

commit: a125d6a

[github-actions]

Developer playground preview: https://rescript-lang.github.io/rescript/dev-playground/?version=pr-8805

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 4bff2f4bdb

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".