string.format: refuse the float conversions

[rixnobis]

Numbers are integers in psxlua and the libc printf underneath has no
floating point, so string.format('%f', 1) printed 0.000000 and %g printed a
bare %. The float conversions raise an error now instead.

Summary by CodeRabbit

• Behavior Changes
  • string.format no longer formats floating-point conversions (e, E, f, F, a, A, g, or G). Using these specifiers now returns an error indicating that floating-point formatting is unavailable.

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📝 Walkthrough

Walkthrough

string.format now returns an error for floating-point conversion specifiers. The change removes the floating-point format-length configuration, and %a and %A are rejected unconditionally.

Changes

Floating-point format handling

Layer / File(s)	Summary
Reject floating-point format specifiers src/lstrlib.c	The format parser rejects e, E, f, F, a, A, g, and G with an error stating that floating point is unavailable. The floating-point format-length configuration block is removed.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: 🟡 Moderate · up to e95e9

Scripts using documented floating-point formats now receive errors instead of formatted strings. Restore the supported conversions before merging.

Architecture Summary

Architecture risk: 🔵 Low · up to e95e9

The change affects 1 system.

Changed systems: src

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — src (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

• observed — Modified behavior in src/lstrlib.c: Removed the LUA_FLTFRMLEN and LUA_FLTFRM_T configuration block, including its default definitions for floating-point formatting.
• observed — Modified behavior in src/lstrlib.c: All floating-point format specifiers now return an error identifying the option and stating that floating point is unavailable. This replaces formatting through luaI_sprintf with a configured length modifier; %a and %A are now rejected unconditionally rather than being available under LUA_USE_AFORMAT.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: string.format now refuses floating-point conversions.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

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Inline comments:
Review comments at @src/lstrlib.c:
- Around line 922-927: Restore floating-point formatting for the previously
supported %e, %E, %f, %g, and %G conversions in the format conversion switch,
using the existing soft-float support. Keep %a and %A gated by LUA_USE_AFORMAT,
and leave %F unsupported.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: f146988d-e61c-44c8-b105-2d755f711b08

📥 Commits

Reviewing files that changed from the base of the PR and between 24ffd3e and e95e934.

📒 Files selected for processing (1)

• src/lstrlib.c

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