[STUPIDCONTEM]

Evidence review (2026-10-09)

Closed by maintainer; not ready to reopen. Required evidence: A title that actually reaches a non-C numeric locale; guest setlocale currently accepts only C/POSIX.

Game/title ID: none verified. No PS5 title execution is claimed.

Deferred after maintainer review: guest setlocale currently accepts only C/POSIX, so the host-locale regression does not demonstrate a reachable title failure. Reopening requires a title that encounters this behavior. See maintainer feedback. The patch and test results below are historical and excluded from the current proposed integration.

What

When the host C numeric locale uses a comma decimal separator, libSceJson2 parses valid JSON 1.5 as 1 and serializes real 1.5 as invalid JSON 1,5. JSON requires a literal decimal point (RFC 8259 section 6).

Parse real numbers with an immutable C numeric locale and verify the full token was consumed. Format real numbers with locale-independent to_chars at the existing 17-digit precision. Preserve native strtod range/subnormal handling and existing -0 spelling. No process-wide locale changes are made by the library.

Tested

Windows 10 Pro 19045, WinLibs GCC 15.2.0 UCRT posix SEH r7, Release, BUILD_TESTING=ON. Independent branch from f145139676a48306681d3a4d5fabf83938759daf.

• Extended guest_json fails on unchanged upstream at comma-locale ParseReal("1.5") == 1.5 and passes three focused runs with the fix.
• Cases cover fractional/exponent parsing and serialization, signed zero and underflow, smallest subnormal and maximum finite double round trips, existing overflow rejection, and restoration of the previous host locale.
• The comma-decimal locale is available and exercised on this Windows host. That portion is conditional on locale availability on other systems; C-locale cases always run.
• Full default and explicit libs builds passed; full CTest: 488/488, 29.52 seconds. Committed-head conventions, whitespace and test-registration checks passed.
• Parent independently reviewed and tested the final implementation; a second agent reviewed locale ownership and numeric boundaries.

Guest setlocale currently accepts C/POSIX only, so this fixes dependence on locale changes made by host/native code. Linux, PS5 hardware and titles were not tested locally. Open #1390 changes initializer/RTTI exports and #2004 changes object emptiness; neither implements these numeric functions.

Checklist

• Based on current main; no other open PR implements the same change (historical base; current readiness not asserted)
• One topic per PR; follow-ups go in a new PR
• No comments added to code
• Unimplemented paths throw; no silent stubs added
• No investigation notes, reports or images added to the repository
• No third-party code added
• Generic behaviour, not specific to one title
• Depends on: none
• AI-assisted: yes; parent independently reviewed and tested the final change.

[oneandonlydean]

Closing: guest setlocale only accepts C/POSIX, so no title can put the library in a comma locale here. Reopen with a title that hits it.