Support multiple -f/--file pattern inputs for ripgrep CLI compatibility #200

Summary

tgrep accepts only one -f/--file argument. Repeating it causes an argument-parser error, while ripgrep accumulates patterns from all supplied files.

This is a CLI compatibility request. The immediate error makes this easier to detect than the silent pattern loss across search described in a separate report. It is also different from #181, which concerned the contents of one pattern file.

Reproduce

mkdir repro-multiple-pattern-files && cd repro-multiple-pattern-files
mkdir data
printf 'foo\nbar\nbaz\n' > data/input.txt
printf 'foo\n' > p1.txt
printf 'bar\n' > p2.txt

tgrep --no-index -I -f p1.txt -f p2.txt -- data
rg               -I -f p1.txt -f p2.txt -- data

tgrep stderr:

error: the argument '--file <PATTERN_FILE>' cannot be used multiple times

The rejection occurs during parsing, before any search backend runs. This is not a three-backend reproduction claim.

Environment

• tgrep 1.2.0, official Windows x86_64 release.
• Source inspected at release commit 3ba6ee02537281b68ee1366bb40df9f8b7cc54f0.
• Windows; test harness run with PowerShell 7.
• ripgrep 15.1.0 (af60c2de9d).
• Verified on 2026-10-12. The shell examples describe the same fixture bytes and arguments tested on Windows.

Cause

The pattern file field is Option<String> in tgrep-cli/src/main.rs:88, unlike the list-valued -e field.

Possible fix

Accept an ordered collection of pattern-file inputs and combine their patterns with the existing -e inputs. Preserve the already fixed blank-line, empty-file, and whitespace semantics from #181/#187.

A regression could check two files that contribute different patterns, an empty file combined with a nonempty file, and combinations with -e.