External Dependencies at Build Time

[mys721tx]

Output of brew config

HOMEBREW_VERSION: 4.0.6-8-g0a6dffd
ORIGIN: https://github.com/Homebrew/brew
HEAD: 0a6dffdcf96588ad064b7c0395458821bf27cf88
Last commit: 65 minutes ago
Core tap origin: https://github.com/Homebrew/homebrew-core
Core tap HEAD: c26f1c8714c231ee6796915f033ba229c89af3d6
Core tap last commit: 4 weeks ago
Core tap branch: master
Core tap JSON: 11 Mar 16:50 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: /private/tmp/com.apple.launchd.whehDGlItY/org.xquartz:0
HOMEBREW_EDITOR: vim
HOMEBREW_GITHUB_API_TOKEN: set
HOMEBREW_MAKE_JOBS: 10
Homebrew Ruby: 2.6.10 => /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby
CPU: 10-core 64-bit arm_firestorm_icestorm
Clang: 14.0.0 build 1400
Git: 2.37.1 => /Applications/Xcode.app/Contents/Developer/usr/bin/git
Curl: 7.86.0 => /usr/bin/curl
macOS: 13.2.1-arm64
CLT: 14.2.0.0.1.1668646533
Xcode: 14.2
Rosetta 2: false

Output of brew doctor

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Uncommitted files:
  ?? Formula/picotool.rb

Description of issue

I am writing a formula for raspberrypi/picotool and it depends on raspberrypi/pico-sdk at build time. Since the SDK is for RP2040, we probably should not make a formula for it. What is the standard way to handle an external dependency at build time?

[ZhongRuoyu]

You may make pico-sdk a resource. See telnet.rb for an example, where libtelnet is added as a resource and built in the install method below.

[mys721tx]

Thanks! Homebrew/homebrew-core#125398 submitted.

[AltonMusinski3]

If you have a build-time dependency that cannot be installed through Homebrew, you can add the dependency as a resource to your formula. A resource is a file or a directory that is downloaded or copied into the build directory before building the formula.

In your case, you can add the Pico SDK as a resource to your formula, so that it is available during the build process. Here is an example of how you can do it:
class MyFormula < Formula
desc "My formula"
homepage "https://example.com"
url "https://example.com/archive/v1.0.tar.gz"
sha256 "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"

resource "pico-sdk" do
url "https://github.com/raspberrypi/pico-sdk/archive/master.tar.gz"
sha256 "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
end

def install
# Copy the Pico SDK into the build directory
resource("pico-sdk").stage do
cp_r ".", buildpath/"pico-sdk"
end

# Build your formula using the Pico SDK
system "make", "SDK_PATH=#{buildpath}/pico-sdk", "install"

end

test do
# ...
end
end

In this example, the Pico SDK is added as a resource to the formula using the resource method. The stage block is used to download and extract the SDK into the build directory. The install method is then modified to pass the path to the SDK as a variable to the build command.

You can replace the URL and SHA256 checksum of the Pico SDK with the ones that are appropriate for your use case.