[jayhemnani9910]

\< and \> only work when something else in the pattern makes it a regular expression. On their own they go to the literal matcher, which drops the backslash, so sed looks for a real < or >:

$ echo 'foo <foo> food' | ./target/debug/sed 's/\<foo\>/X/g'
foo X food
$ echo 'foo <foo> food' | /usr/bin/sed 's/\<foo\>/X/g'    # GNU sed 4.9
X <X> food

s/\<f.o\>/X/g already gives X <X> food, since the . sends it to the regex engine. Addresses are affected the same way: /\<bar/p prints <bar but not bar.

NEEDS_RE already lists \b and \B as empty matches that need a regular expression. This adds \< and \> next to them. Both engines read them as word start and word end. --posix is unchanged, since there the parser already turns them into plain < and >.

Tests: test_needs_re_matches gets \<foo and foo\>, and test_word_boundaries_without_other_regex_characters checks s/\<foo\>/X/g and /\<bar/p against GNU sed 4.9's output. Both fail without the change. cargo test: 747 passed (746 on main plus the new one), clippy and rustfmt clean.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.94%. Comparing base (3e86e42) to head (2cf1706).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #612   +/-   ##
=======================================
  Coverage   94.93%   94.94%           
=======================================
  Files          14       14           
  Lines        7292     7294    +2     
  Branches      434      434           
=======================================
+ Hits         6923     6925    +2     
  Misses        368      368           
  Partials        1        1           

Flag	Coverage Δ
macos_latest	96.46% <100.00%> (+<0.01%)	⬆️
ubuntu_latest	96.40% <100.00%> (+<0.01%)	⬆️
windows_latest	0.00% <0.00%> (ø)

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[codspeed]

Merging this PR will improve performance by 14.37%

⚠️ 1 benchmark spent significant time in system calls

System calls cannot be consistently instrumented, so they are not included in the measure, which understates the real cost. Please switch to the Walltime instrument to accurately measure system calls.

Measurement and system calls

• access_log_append

⚠️ 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
✅ 10 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	number_fix	1.3 s	1.1 s	+14.37%

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing jayhemnani9910:word-boundaries-literal-path (2cf1706) with main (3e86e42)}

[sylvestre]

Thanks for your PR