[mazen320]

What

Wide formatting now preserves the zero digit for alternate-form octal output with precision zero: swprintf(..., u"%#.0o", 0u) produces 0 instead of an empty string. The shared wide formatter applies the same normalization already present in the narrow formatter, after narrowing h/hh arguments and before host formatting.

The reference is FreeBSD 11.4 vfwprintf.c, number conversion, which retains zero for alternate octal even when precision is zero. This is source-based compatibility work; it was not measured on a PS5.

Related #5293 and #5303 address additional conversions. This change covers the residual alternate-octal case, does not close the broader issue, and merges cleanly with the current #5303 head in a local merge-tree check. That combination was not executed.

Tested

Windows, WinLibs GCC 15.2.0 UCRT, Release, based on main 02b5a8e55.

• With only the regression added to main, guest_wide_formatting aborts at swprintf alternate octal zero.
• After the two-line implementation change, guest_wide_formatting, guest_formatting, all three guest_standard_streams modes and file_streams pass (6/6).
• New cases cover swprintf, vswprintf, snwprintf_s, empty/zero precision, field width, alignment, zero padding, dynamic and positional precision, h/hh narrowing, long long, bounded output, and unaffected hexadecimal/unflagged/nonzero cases.
• python tools/check_conventions.py --base upstream/main and git diff --check pass. Linux and a console/title run were not performed.
• tools/pr_overlap.py reported only an uncomparable shared test file in test: organize library tests and label CTest suites #6044; manual inspection shows it is a pure rename to tests/runtime/GuestWideFormatting.cpp (zero additions/deletions), with no duplicate logic.

Checklist

• Based on current main; no other open PR implements the same functions (no duplicate alternate-octal fix found; related fix(libc): follow measured wide printf behavior #5303 changes other cases in the shared wide formatter)
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none
• Fixes: none
• Unblocks: none
• GPUs tested: n/a
• AI-assisted: yes

[github-actions]

Some comparisons could not be completed because a pull request conflicts with the base branch. Review these shared files manually before concluding that there is no overlap.

Pull request	Shared files not compared
PR 6044	core/libs/tests/GuestWideFormatting.cpp