Fix cask installation conflicts with same-named formula binaries by Copilot · Pull Request #20417 · Homebrew/brew

Copilot · 2025-08-11T12:43:34Z

When installing a cask after a formula with the same name (e.g., brew install docker followed by brew install --cask docker), the cask installation would fail with errors like:

Error: It seems there is already a Binary at '/opt/homebrew/etc/bash_completion.d/docker'.

This occurred because both the formula and cask tried to install files to the same locations (binaries, completion files), and the cask installer would fail when it encountered existing symlinks.

This PR adds intelligent conflict detection to the cask artifact installation process. When a cask tries to install a binary or completion file that already exists as a symlink from a formula with the same name:

Detects the conflict by checking if the existing symlink points to the formula's Cellar directory
Skips linking that specific file instead of failing
Shows a clear warning message to inform the user
Continues installation of non-conflicting artifacts

Example output after the fix:

==> Installing Cask docker
==> Moving App 'Docker.app' to '/Applications/Docker.app'
Warning: It seems there is already a Binary at '/usr/local/bin/docker' from formula docker; skipping.
Warning: It seems there is already a Bash Completion at '/opt/homebrew/etc/bash_completion.d/docker' from formula docker; skipping.
🍺  docker was successfully installed!

The solution allows both formula CLI tools and cask GUI applications to coexist, resolving a common user workflow issue while maintaining backward compatibility for all other cases.

Fixes #16309.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

eu-central-1-1.aws.cloud2.influxdata.com
- Triggering command: /bin/curl --disable --cookie /dev/null --globoff --user-agent Linuxbrew/4.6.0-61-gd85c5c9 (Linux; x86_64 Ubuntu 24.04.2 LTS) curl/8.5.0 --header Accept-Language: en --fail --progress-bar --retry 3 --max-time 3 --header Authorization: Token iVdsgJ_OjvTYGAA79gOfWlA_fX0QCuj4eYUNdb-qVUTrC3tp3JTWCADVNE9HxV0kp2ZjIK9tuthy_teX4szr9A== --header Content-Type: text/plain; charset=utf-8 --header Accept: application/json --data-binary command_run,command=typecheck,ci=true,devcmdrun=true,developer=false options="" 1754916917 --silent --output /dev/null REDACTED (dns block)
- Triggering command: /bin/curl --disable --cookie /dev/null --globoff --user-agent Linuxbrew/4.6.0-61-gd85c5c9 (Linux; x86_64 Ubuntu 24.04.2 LTS) curl/8.5.0 --header Accept-Language: en --fail --progress-bar --retry 3 --max-time 3 --header Authorization: Token iVdsgJ_OjvTYGAA79gOfWlA_fX0QCuj4eYUNdb-qVUTrC3tp3JTWCADVNE9HxV0kp2ZjIK9tuthy_teX4szr9A== --header Content-Type: text/plain; charset=utf-8 --header Accept: application/json --data-binary command_run,command=typecheck,ci=true,devcmdrun=true,developer=false options="" 1754917362 --silent --output /dev/null REDACTED (dns block)
- Triggering command: /bin/curl --disable --cookie /dev/null --globoff --user-agent Linuxbrew/4.6.0-61-gd85c5c9 (Linux; x86_64 Ubuntu 24.04.2 LTS) curl/8.5.0 --header Accept-Language: en --fail --progress-bar --silent --retry 3 --max-time 3 --header Authorization: Token iVdsgJ_OjvTYGAA79gOfWlA_fX0QCuj4eYUNdb-qVUTrC3tp3JTWCADVNE9HxV0kp2ZjIK9tuthy_teX4szr9A== --header Content-Type: text/plain; charset=utf-8 --header Accept: application/json --data-binary command_run,command=typecheck,ci=true,devcmdrun=true,developer=false options="" 1754917376 --silent --output /dev/null REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

Library/Homebrew/test/cask/artifact/bashcompletion_spec.rb

Library/Homebrew/cask/artifact/symlinked.rb

MikeMcQuaid · 2025-08-11T15:41:15Z

@copilot address the review comments I've left inline on this PR

Copilot · 2025-08-11T15:57:26Z

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

eu-central-1-1.aws.cloud2.influxdata.com
- Triggering command: /bin/curl --disable --cookie /dev/null --globoff --user-agent Linuxbrew/4.6.0-63-gb6a3f85 (Linux; x86_64 Ubuntu 24.04.2 LTS) curl/8.5.0 --header Accept-Language: en --fail --progress-bar --retry 3 --max-time 3 --header Authorization: Token iVdsgJ_OjvTYGAA79gOfWlA_fX0QCuj4eYUNdb-qVUTrC3tp3JTWCADVNE9HxV0kp2ZjIK9tuthy_teX4szr9A== --header Content-Type: text/plain; charset=utf-8 --header Accept: application/json --data-binary command_run,command=typecheck,ci=true,devcmdrun=true,developer=false options="" 1754927619 --silent --output /dev/null REDACTED (dns block)
- Triggering command: /bin/curl --disable --cookie /dev/null --globoff --user-agent Linuxbrew/4.6.0-63-gb6a3f85 (Linux; x86_64 Ubuntu 24.04.2 LTS) curl/8.5.0 --header Accept-Language: en --fail --progress-bar --retry 3 --max-time 3 --header Authorization: Token iVdsgJ_OjvTYGAA79gOfWlA_fX0QCuj4eYUNdb-qVUTrC3tp3JTWCADVNE9HxV0kp2ZjIK9tuthy_teX4szr9A== --header Content-Type: text/plain; charset=utf-8 --header Accept: application/json --data-binary command_run,command=style,ci=true,devcmdrun=true,developer=false options="--fix" 1754927632 --silent --output /dev/null REDACTED (dns block)
- Triggering command: /bin/curl --disable --cookie /dev/null --globoff --user-agent Linuxbrew/4.6.0-63-gb6a3f85 (Linux; x86_64 Ubuntu 24.04.2 LTS) curl/8.5.0 --header Accept-Language: en --fail --progress-bar --retry 3 --max-time 3 --header Authorization: Token iVdsgJ_OjvTYGAA79gOfWlA_fX0QCuj4eYUNdb-qVUTrC3tp3JTWCADVNE9HxV0kp2ZjIK9tuthy_teX4szr9A== --header Content-Type: text/plain; charset=utf-8 --header Accept: application/json --data-binary command_run,command=tests,ci=true,devcmdrun=true,developer=false options="--only=" 1754927648 --silent --output /dev/null REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

Configure Actions setup steps to set up my environment, which run before the firewall is enabled
Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

MikeMcQuaid

@copilot please address these changes and edit the .github/copilot-instructions.md file based on my feedback e.g. no typed: strict needed for tests.

Library/Homebrew/test/cask/artifact/symlinked_spec.rb

Library/Homebrew/test/cask/artifact/binary_spec.rb

Library/Homebrew/test/cask/artifact/zshcompletion_spec.rb

Copilot · 2025-08-11T16:46:37Z

@copilot please address these changes and edit the .github/copilot-instructions.md file based on my feedback e.g. no typed: strict needed for tests.

I've addressed all the feedback by removing typed: strict from the test files and updating the copilot instructions to clarify that typed: strict is not needed for test files. Commit: 793ca7d

While we're at it, update copilot instructions. Co-authored-by: MikeMcQuaid <[email protected]>

Copilot AI assigned Copilot and MikeMcQuaid Aug 11, 2025

Copilot started work on behalf of MikeMcQuaid August 11, 2025 12:43 View session

Copilot AI changed the title ~~[WIP] brew install --cask docker fails after having done brew install docker~~ Fix cask installation conflicts with same-named formula binaries Aug 11, 2025

Copilot AI requested a review from MikeMcQuaid August 11, 2025 13:20

Copilot finished work on behalf of MikeMcQuaid August 11, 2025 13:20

MikeMcQuaid reviewed Aug 11, 2025

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Copilot started work on behalf of MikeMcQuaid August 11, 2025 15:41 View session

Copilot AI requested a review from MikeMcQuaid August 11, 2025 15:57

Copilot finished work on behalf of MikeMcQuaid August 11, 2025 15:57

MikeMcQuaid reviewed Aug 11, 2025

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Copilot started work on behalf of MikeMcQuaid August 11, 2025 16:36 View session

Copilot AI requested a review from MikeMcQuaid August 11, 2025 16:47

Copilot finished work on behalf of MikeMcQuaid August 11, 2025 16:47

Implement formula conflict detection for cask binary artifacts

cbe3477

While we're at it, update copilot instructions. Co-authored-by: MikeMcQuaid <[email protected]>

MikeMcQuaid force-pushed the copilot/fix-16309 branch from 793ca7d to cbe3477 Compare August 12, 2025 09:43

MikeMcQuaid approved these changes Aug 12, 2025

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MikeMcQuaid marked this pull request as ready for review August 12, 2025 09:44

MikeMcQuaid enabled auto-merge August 12, 2025 10:00

Rylan12 approved these changes Aug 12, 2025

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MikeMcQuaid added this pull request to the merge queue Aug 12, 2025

Merged via the queue into main with commit 9626817 Aug 12, 2025
36 of 37 checks passed

MikeMcQuaid deleted the copilot/fix-16309 branch August 12, 2025 17:37

cho-m mentioned this pull request Aug 13, 2025

docker-completion install failure Homebrew/homebrew-core#230224

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MikeMcQuaid mentioned this pull request Aug 18, 2025

New and improved conflicts_with handling for formulae and casks #16398

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cho-m mentioned this pull request Sep 12, 2025

cmake Consistently Shows as Outdated Homebrew/homebrew-core#236514

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yermulnik mentioned this pull request Apr 3, 2026

feat(goreleaser/homebrew): Migrate from Formula to Cask warrensbox/terraform-switcher#732

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Fix cask installation conflicts with same-named formula binaries#20417

Fix cask installation conflicts with same-named formula binaries#20417
MikeMcQuaid merged 1 commit intomainfrom
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I tried to connect to the following addresses, but was blocked by firewall rules:

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I tried to connect to the following addresses, but was blocked by firewall rules:

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