-f drops blank lines and trims whitespace in pattern files; an empty pattern file matches every line #181

Summary

-f/--file reads pattern files differently from ripgrep. Every line is trimmed and blank lines are dropped, so:

• a blank line, which ripgrep treats as an empty pattern that matches every line, is ignored;
• leading and trailing whitespace is removed from each pattern ( test is searched as test);
• an empty pattern file matches every line and exits 0, while ripgrep matches nothing and exits 1.

ripgrep documents the first case explicitly: "Empty pattern lines will match all input lines, and the newline is not counted as part of the pattern."

All three happen with --no-index, with the on-disk index, and through tgrep serve.

Reproduce

mkdir repro && cd repro
printf 'alpha\nbeta\n' > a.txt
printf 'alpha\n\n'     > blank_line.txt   # "alpha" plus one empty pattern
: >                      empty.txt        # no patterns at all
printf ' test\n'       > b.txt
printf ' test\n'       > space.txt        # one pattern with a leading space

tgrep --no-index -n -f blank_line.txt a.txt
tgrep --no-index -n -f empty.txt a.txt
tgrep --no-index -o -f space.txt b.txt

Environment

• tgrep 1.1.0, built from 1120aca (current main) with rustc 1.95.0 (59807616e 2026-04-14)
• Windows 11 Pro (build 28000); the code involved is platform-independent
• Same results with --no-index, with a local index (tgrep index .), and through tgrep serve

Cause

SearchOptions::all_patterns trims each line of the pattern file and skips it if the result is empty:

For an empty file the pattern list ends up empty. combine_patterns then joins zero patterns into (?:), which matches everywhere, and build_multi_pattern_plan returns MatchAll for zero patterns. The client builds the server request from the same list (search.rs#L994), so serve behaves the same way.

Possible fix

• Keep each line as written. str::lines already strips both \n and \r\n, so dropping the trim() and the empty-line filter is enough, and pattern files with CRLF line endings keep working (a file containing alpha\r\n finds alpha in both tools today).
• Treat "no patterns" as "matches nothing" rather than as one empty pattern: skip the search and exit 1, as ripgrep does. An empty line in the file is one empty pattern and should still match every line.

A regression test could run the three cases above with --no-index, against a local index, and through serve.