Make Unicode listing GNU-sed compatible

[dspinellis]

Adjust l command to list Unicode characters by default as octal byte sequences of the corresponding UTF-8 bytes. A new -U --uutil-extensions option allows listing them with the common Unicode \u and \U hex escapes.

This implementation is compatible with the byte-handling changes and also retains the useful \u behavior, which #436 would loose.

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 83.20%. Comparing base (79e5df0) to head (1688d27).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/sed/processor.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #537      +/-   ##
==========================================
+ Coverage   83.18%   83.20%   +0.02%     
==========================================
  Files          13       13              
  Lines        7001     7010       +9     
  Branches      398      398              
==========================================
+ Hits         5824     5833       +9     
  Misses       1174     1174              
  Partials        3        3              

Flag	Coverage Δ
macos_latest	83.85% <90.00%> (+0.02%)	⬆️
ubuntu_latest	84.05% <90.00%> (+0.02%)	⬆️
windows_latest	0.00% <0.00%> (ø)

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[Copilot]

Pull request overview

Updates the l (list) command output to be GNU-sed compatible by defaulting to octal-escaped UTF-8 bytes for non-ASCII, while introducing a -U/--uutil-extensions flag to preserve uutils-specific \uXXXX / \UXXXXXXXX Unicode escape listing.

Changes:

• Change l command listing behavior to emit octal byte escapes by default (even under UTF-8 locales), reserving \u/\U Unicode escapes for --uutil-extensions.
• Add -U/--uutil-extensions CLI flag and plumb it through ProcessingContext.
• Add/adjust fixtures and tests to cover both default octal behavior and extension-enabled Unicode-escape behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/fixtures/sed/output/list_unicode_octal	Adds expected output fixture for default octal UTF-8 byte escaping in l output.
tests/by-util/test_sed.rs	Updates Unicode listing tests to cover both extension-enabled and default behaviors.
src/sed/processor.rs	Switches l behavior based on uutil_extensions and character mode.
src/sed/mod.rs	Adds -U/--uutil-extensions flag and wires it into context construction and tests.
src/sed/command.rs	Extends ProcessingContext with uutil_extensions.
README.md	Documents the new incompatible-extensions toggle and its effect on l output.

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[codspeed-hq]

Merging this PR will regress 1 benchmark

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 9 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	access_log_subst	2.4 s	2.5 s	-6.33%
⚡	number_fix	1.4 s	1.3 s	+9.78%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing dspinellis:octal-list (1688d27) with main (7be1f77)}

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.