cmd/deps: accept --brewfile as an input source

[andrew]

Adds --brewfile to brew deps, matching the flag on brew vulns. brew and cask entries from the Brewfile are treated as if they'd been passed as named arguments, so the flag composes with --tree, --graph, --for-each, --union and the default flat listing. --formula/--cask filter which entry types are loaded; tap, mas and other extension entries are ignored.

A bare --brewfile reads ./Brewfile; --brewfile=<path> reads a specific file.

$ cat Brewfile
brew "jq"
brew "wget"

$ brew deps --tree --brewfile
jq
└── oniguruma

wget
├── libidn2
│   ├── libunistring
│   └── gettext
│       ├── json-c
│       └── libunistring
├── libpsl
├── openssl@3
│   └── ca-certificates
├── gettext
│   ├── json-c
│   └── libunistring
└── libunistring

Motivation: seeing what a Brewfile will pull in before running brew bundle, and inspecting a project's toolchain footprint in CI without installing anything.

The brewfile_path normalisation helper is copied from cmd/vulns.rb; happy to extract it if a third command grows the same flag.

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• AI was used to generate or assist with generating this PR.

Written with Claude Code; I read the diff, exercised --tree, --graph --dot, --for-each, --union, and --formula/--cask filtering against a local Brewfile, and ran brew lgtm locally.

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[Copilot]

Pull request overview

This PR adds --brewfile support to brew deps, allowing dependency output modes (--tree, --graph, --for-each, --union, and default listing) to use formulae/casks from a Brewfile as inputs, similar to brew vulns.

Changes:

• Add --brewfile flag to brew deps and load formula/cask entries from a Brewfile as command inputs.
• Add an integration spec covering --brewfile=<path>.
• Update manpage/docs and shell completions to document the new flag.

Reviewed changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
Library/Homebrew/cmd/deps.rb	Implements --brewfile flag and Brewfile-driven input loading for dependency calculation/output.
Library/Homebrew/test/cmd/deps_spec.rb	Adds an integration test verifying --brewfile=<path> behavior with --tree.
Library/Homebrew/sorbet/rbi/dsl/homebrew/cmd/deps.rbi	Adds the brewfile args accessor to the generated RBI for brew deps.
manpages/brew.1	Documents brew deps --brewfile in the main manpage.
docs/Manpage.md	Documents brew deps --brewfile in the Markdown manpage source.
completions/zsh/_brew	Adds --brewfile to zsh completions for brew deps.
completions/fish/brew.fish	Adds --brewfile to fish completions for brew deps.
completions/bash/brew	Adds --brewfile to bash completions for brew deps.

Files not reviewed (1)

• Library/Homebrew/sorbet/rbi/dsl/homebrew/cmd/deps.rbi: File type not supported

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[MikeMcQuaid]

Looks good thanks!