Having trouble making a formula work on both macOS and Linux

[mainrs]

It seems that Linux binaries are meant to be statically linked. However, I couldn't find any instructions on how to run different install commands depending on what the OS is. I have zero Ruby experience, so maybe the solution is quite obvious. For completeness, I just need to pass an argument to cargo if I am building on linux.

Is a better approach to have two different taps, one per OS? It seems that that is what homebrew does (linuxbrew-core and homebrew-core). If that is the case, how does homebrew know which to use?

class GhLabelsCli < Formula
  desc "CLI for managing labels in existing GitHub repositories"
  homepage "https://github.com/SirWindfield/gh-labels-cli"
  url "https://github.com/SirWindfield/gh-labels-cli/archive/v0.1.8.tar.gz"
  sha256 "ad66dedf7fcd42d9c3cac0430a6e3d667cf4f197103392aa09635e5e2f3a2f84"
  license any_of: ["Apache-2.0", "MIT"]
  head "https://github.com/SirWindfield/gh-labels-cli.git"

  depends_on "rust" => :build
  # depends_on :macos

  def install
    system "cargo", "install", *std_cargo_args
  end

  test do
    system "#{bin}/gh-labels", "help"
  end
end

[SMillerDev]

It seems that Linux binaries are meant to be statically linked.

They are not, homebrew prefers shared binaries whenever possible.

I couldn't find any instructions on how to run different install commands depending on what the OS is.

Look in homebrew-core for usage of on_linux and on_macos

[mainrs]

They are not, homebrew prefers shared binaries whenever possible.

Then what does this error message mean? Because I interpreted it that way:

==> brew linkage --test sirwindfield/tap/gh-labels-cli
==> FAILED
Unwanted system libraries:
  /lib/x86_64-linux-gnu/libz.so.1

Look in homebrew-core for usage of on_linux and on_macos

Thanks!

[gromgit]

That simply says that your formula links with system libraries other than the glibc and gcc ones, so any bottles created from this formula can break on Linux boxes that don't have the same versions of said libraries installed...or don't have them at all.

The fix is simple:

depends_on  "zlib"

[carlocab]

This is probably better:

uses_from_macos "zlib"

[mainrs]

That simply says that your formula links with system libraries other than the glibc and gcc ones, so any bottles created from this formula can break on Linux boxes that don't have the same versions of said libraries installed...or don't have them at all.

The fix is simple:

depends_on  "zlib"

Ah! Thanks for letting me know!