extend: add on_os (for on_macos/on_linux)

Library/Homebrew/extend/on_os.rb

@@ -0,0 +1,22 @@
+# typed: true
+# frozen_string_literal: true
+
+module OnOS
+  # Block only executed on macOS. No-op on Linux.
+  # <pre>on_macos do
+  # # Do something Mac-specific
+  # end</pre>
+  def on_macos(&block)
+    raise "No block content defined for on_macos block" unless block
+  end
+
+  # Block only executed on Linux. No-op on macOS.
+  # <pre>on_linux do
+  # # Do something Linux-specific
+  # end</pre>
+  def on_linux(&block)
+    raise "No block content defined for on_linux block" unless block
+  end
+end
+
+require "extend/os/on_os"

Library/Homebrew/extend/on_os.rbi

@@ -0,0 +1,5 @@
+# typed: strict
+
+module OnOS
+  include Kernel
+end

Library/Homebrew/extend/os/formula.rb

@@ -1,8 +1,4 @@
 # typed: strict
 # frozen_string_literal: true
 
-if OS.mac?
+require "extend/os/linux/formula" if OS.linux?
-  require "extend/os/mac/formula"
-elsif OS.linux?
-  require "extend/os/linux/formula"
-end

Library/Homebrew/extend/os/linux/formula.rb

@@ -2,14 +2,6 @@
 # frozen_string_literal: true
 
 class Formula
-  undef on_linux
-
-  def on_linux(&block)
-    raise "No block content defined for on_linux block" unless block
-
-    yield
-  end
-
   undef shared_library
 
   def shared_library(name, version = nil)
@@ -17,14 +9,6 @@ class Formula
   end
 
   class << self
-    undef on_linux
-
-    def on_linux(&block)
-      raise "No block content defined for on_linux block" unless block
-
-      yield
-    end
-
     undef ignore_missing_libraries
 
     def ignore_missing_libraries(*libs)

Library/Homebrew/extend/os/linux/on_os.rb

@@ -0,0 +1,10 @@
+# typed: true
+# frozen_string_literal: true
+
+module OnOS
+  def on_linux(&block)
+    raise "No block content defined for on_linux block" unless block
+
+    yield
+  end
+end

Library/Homebrew/extend/os/linux/resource.rb

@@ -1,10 +0,0 @@
-# typed: true
-# frozen_string_literal: true
-
-class Resource
-  undef on_linux
-
-  def on_linux(&_block)
-    yield
-  end
-end

Library/Homebrew/extend/os/mac/formula.rb

@@ -1,22 +0,0 @@
-# typed: true
-# frozen_string_literal: true
-
-class Formula
-  undef on_macos
-
-  def on_macos(&block)
-    raise "No block content defined for on_macos block" unless block
-
-    yield
-  end
-
-  class << self
-    undef on_macos
-
-    def on_macos(&block)
-      raise "No block content defined for on_macos block" unless block
-
-      yield
-    end
-  end
-end

Library/Homebrew/extend/os/mac/on_os.rb

@@ -0,0 +1,10 @@
+# typed: true
+# frozen_string_literal: true
+
+module OnOS
+  def on_macos(&block)
+    raise "No block content defined for on_macos block" unless block
+
+    yield
+  end
+end

Library/Homebrew/extend/os/mac/resource.rb

@@ -1,10 +0,0 @@
-# typed: true
-# frozen_string_literal: true
-
-class Resource
-  undef on_macos
-
-  def on_macos(&_block)
-    yield
-  end
-end

Library/Homebrew/extend/os/on_os.rb

@@ -2,7 +2,7 @@
 # frozen_string_literal: true
 
 if OS.mac?
-  require "extend/os/mac/resource"
+  require "extend/os/mac/on_os"
 elsif OS.linux?
-  require "extend/os/linux/resource"
+  require "extend/os/linux/on_os"
 end

Library/Homebrew/formula.rb

@@ -25,6 +25,7 @@ require "tab"
 require "mktemp"
 require "find"
 require "utils/spdx"
+require "extend/on_os"
 
 # A formula provides instructions and metadata for Homebrew to install a piece
 # of software. Every Homebrew formula is a {Formula}.
@@ -59,6 +60,7 @@ class Formula
   include Utils::Shebang
   include Utils::Shell
   include Context
+  include OnOS
   extend Enumerable
   extend Forwardable
   extend Cachable
@@ -1389,22 +1391,6 @@ class Formula
     "#<Formula #{name} (#{active_spec_sym}) #{path}>"
   end
 
-  # Block only executed on macOS. No-op on Linux.
-  # <pre>on_macos do
-  # # Do something Mac-specific
-  # end</pre>
-  def on_macos(&block)
-    raise "No block content defined for on_macos block" unless block
-  end
-
-  # Block only executed on Linux. No-op on macOS.
-  # <pre>on_linux do
-  # # Do something Linux-specific
-  # end</pre>
-  def on_linux(&block)
-    raise "No block content defined for on_linux block" unless block
-  end
-
   # Standard parameters for cargo builds.
   def std_cargo_args
     ["--locked", "--root", prefix, "--path", "."]
@@ -2238,6 +2224,7 @@ class Formula
   # The methods below define the formula DSL.
   class << self
     include BuildEnvironment::DSL
+    include OnOS
 
     def method_added(method)
       super
@@ -2557,22 +2544,6 @@ class Formula
       specs.each { |spec| spec.uses_from_macos(dep, bounds) }
     end
 
-    # Block only executed on macOS. No-op on Linux.
-    # <pre>on_macos do
-    #   depends_on "mac_only_dep"
-    # end</pre>
-    def on_macos(&block)
-      raise "No block content defined for on_macos block" unless block
-    end
-
-    # Block only executed on Linux. No-op on macOS.
-    # <pre>on_linux do
-    #   depends_on "linux_only_dep"
-    # end</pre>
-    def on_linux(&block)
-      raise "No block content defined for on_linux block" unless block
-    end
-
     # @!attribute [w] option
     # Options can be used as arguments to `brew install`.
     # To switch features on/off: `"with-something"` or `"with-otherthing"`.

Library/Homebrew/resource.rb

@@ -5,6 +5,7 @@ require "download_strategy"
 require "checksum"
 require "version"
 require "mktemp"
+require "extend/on_os"
 
 # Resource is the fundamental representation of an external resource. The
 # primary formula download, along with other declared resources, are instances
@@ -16,6 +17,7 @@ class Resource
 
   include Context
   include FileUtils
+  include OnOS
 
   attr_reader :mirrors, :specs, :using, :source_modified_time, :patches, :owner
   attr_writer :version
@@ -189,18 +191,6 @@ class Resource
     patches << p
   end
 
-  # Block only executed on macOS. No-op on Linux.
-  # <pre>on_macos do
-  #   url "mac_only_url"
-  # end</pre>
-  def on_macos(&_block); end
-
-  # Block only executed on Linux. No-op on macOS.
-  # <pre>on_linux do
-  #   url "linux_only_url"
-  # end</pre>
-  def on_linux(&_block); end
-
   protected
 
   def mktemp(prefix, &block)
@@ -280,5 +270,3 @@ class ResourceStageContext
     "<#{self.class}: resource=#{resource} staging=#{staging}>"
   end
 end
-
-require "extend/os/resource"