Deprecate OS::Mac on Linux

Library/Homebrew/cmd/gist-logs.rb

@@ -73,9 +73,7 @@ def gistify_logs(formula, args:)
       EOS
     end
 
-    if args.new_issue?
-      url = GitHub.create_issue(formula.tap, "#{formula.name} failed to build on #{MacOS.full_version}", url)
-    end
+    url = GitHub.create_issue(formula.tap, "#{formula.name} failed to build on #{OS_VERSION}", url) if args.new_issue?
 
     puts url if url
   end

Library/Homebrew/extend/os/linkage_checker.rb

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

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

@@ -3,9 +3,31 @@
 
 class Formula
   undef valid_platform?
+  undef std_cmake_args
 
   sig { returns(T::Boolean) }
   def valid_platform?
     requirements.none?(LinuxRequirement)
   end
+
+  sig {
+    params(
+      install_prefix: T.any(String, Pathname),
+      install_libdir: T.any(String, Pathname),
+      find_framework: String,
+    ).returns(T::Array[String])
+  }
+  def std_cmake_args(install_prefix: prefix, install_libdir: "lib", find_framework: "LAST")
+    args = generic_std_cmake_args(install_prefix: install_prefix, install_libdir: install_libdir,
+                                  find_framework: find_framework)
+
+    # Avoid false positives for clock_gettime support on 10.11.
+    # CMake cache entries for other weak symbols may be added here as needed.
+    args << "-DHAVE_CLOCK_GETTIME:INTERNAL=0" if MacOS.version == "10.11" && MacOS::Xcode.version >= "8.0"
+
+    # Ensure CMake is using the same SDK we are using.
+    args << "-DCMAKE_OSX_SYSROOT=#{MacOS.sdk_for_formula(self).path}" if MacOS.sdk_root_needed?
+
+    args
+  end
 end

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

@@ -0,0 +1,13 @@
+# typed: true
+# frozen_string_literal: true
+
+class LinkageChecker
+  undef system_libraries_exist_in_cache?
+
+  private
+
+  def system_libraries_exist_in_cache?
+    # In macOS Big Sur and later, system libraries do not exist on-disk and instead exist in a cache.
+    MacOS.version >= :big_sur
+  end
+end

Library/Homebrew/formula.rb

@@ -1646,7 +1646,7 @@ def std_cargo_args(root: prefix, path: ".")
     ).returns(T::Array[String])
   }
   def std_cmake_args(install_prefix: prefix, install_libdir: "lib", find_framework: "LAST")
-    args = %W[
+    %W[
       -DCMAKE_INSTALL_PREFIX=#{install_prefix}
       -DCMAKE_INSTALL_LIBDIR=#{install_libdir}
       -DCMAKE_BUILD_TYPE=Release
@@ -1655,16 +1655,8 @@ def std_cmake_args(install_prefix: prefix, install_libdir: "lib", find_framework
       -Wno-dev
       -DBUILD_TESTING=OFF
     ]
-
-    # Avoid false positives for clock_gettime support on 10.11.
-    # CMake cache entries for other weak symbols may be added here as needed.
-    args << "-DHAVE_CLOCK_GETTIME:INTERNAL=0" if MacOS.version == "10.11" && MacOS::Xcode.version >= "8.0"
-
-    # Ensure CMake is using the same SDK we are using.
-    args << "-DCMAKE_OSX_SYSROOT=#{MacOS.sdk_for_formula(self).path}" if MacOS.sdk_root_needed?
-
-    args
   end
+  alias generic_std_cmake_args std_cmake_args
 
   # Standard parameters for Go builds.
   sig {

Library/Homebrew/linkage_checker.rb

@@ -196,9 +196,8 @@
 
           if (dep = dylib_to_dep(dylib))
             @broken_deps[dep] |= [dylib]
-          elsif MacOS.version >= :big_sur && dylib_found_via_dlopen(dylib)
+          elsif system_libraries_exist_in_cache? && dylib_found_via_dlopen(dylib)
             # If we cannot associate the dylib with a dependency, then it may be a system library.
-            # In macOS Big Sur and later, system libraries do not exist on-disk and instead exist in a cache.
             # If dlopen finds the dylib, then the linkage is not broken.
             @system_dylibs << dylib
           elsif !system_framework?(dylib)
@@ -227,6 +226,11 @@
   end
   alias generic_check_dylibs check_dylibs
 
+  def system_libraries_exist_in_cache?
+    false
+  end
+  alias generic_system_libraries_exist_in_cache? system_libraries_exist_in_cache?
+
   def dylib_found_via_dlopen(dylib)
     Fiddle.dlopen(dylib).close
     true

Library/Homebrew/os/linux.rb

@@ -55,49 +55,60 @@ module Mac
     raise "Loaded OS::Linux on generic OS!" if ENV["HOMEBREW_TEST_GENERIC_OS"]
 
     def self.version
+      # odeprecated "`MacOS.version` on Linux"
       MacOSVersion::NULL
     end
 
     def self.full_version
+      # odeprecated "`MacOS.full_version` on Linux"
       MacOSVersion::NULL
     end
 
     def self.languages
+      # odeprecated "`MacOS.languages` on Linux"
       @languages ||= Array(ENV["LANG"]&.slice(/[a-z]+/)).uniq
     end
 
     def self.language
+      # odeprecated "`MacOS.language` on Linux"
       languages.first
     end
 
     def self.sdk_root_needed?
+      # odeprecated "`MacOS.sdk_root_needed?` on Linux"
       false
     end
 
     def self.sdk_path_if_needed(_version = nil)
+      # odeprecated "`MacOS.sdk_path_if_needed` on Linux"
       nil
     end
 
     def self.sdk_path(_version = nil)
+      # odeprecated "`MacOS.sdk_path` on Linux"
       nil
     end
 
     module Xcode
       def self.version
+        # odeprecated "`MacOS::Xcode.version` on Linux"
         ::Version::NULL
       end
 
       def self.installed?
+        # odeprecated "`MacOS::Xcode.installed?` on Linux"
         false
       end
     end
 
     module CLT
       def self.version
+        # odeprecated "`MacOS::CLT.version` on Linux"
         ::Version::NULL
       end
 
       def self.installed?
+        # odeprecated "`MacOS::CLT.installed?` on Linux"
         false
       end
     end

Library/Homebrew/os/mac.rb

@@ -7,6 +7,9 @@
 require "os/mac/sdk"
 require "os/mac/keg"
 
+# TODO: remove this once the `MacOS` module is undefined on Linux
+require "simulate_system"
+
 module OS
   # Helper module for querying system information on macOS.
   module Mac
@@ -21,13 +24,15 @@ module Mac
     # using the standard Ruby Comparable methods.
     sig { returns(MacOSVersion) }
     def self.version
+      # odeprecated "`MacOS.version` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
       @version ||= full_version.strip_patch
     end
 
     # This can be compared to numerics, strings, or symbols
     # using the standard Ruby Comparable methods.
     sig { returns(MacOSVersion) }
     def self.full_version
+      # odeprecated "`MacOS.full_version` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
       @full_version ||= if ENV["HOMEBREW_FAKE_EL_CAPITAN"] # for Portable Ruby building
         MacOSVersion.new("10.11.6")
       else
@@ -60,6 +65,7 @@ def self.preferred_perl_version
     end
 
     def self.languages
+      # odeprecated "`MacOS.languages` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
       return @languages if @languages
 
       os_langs = Utils.popen_read("defaults", "read", "-g", "AppleLanguages")
@@ -73,6 +79,7 @@ def self.languages
     end
 
     def self.language
+      # odeprecated "`MacOS.language` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
       languages.first
     end
 
@@ -83,6 +90,7 @@ def self.active_developer_dir
 
     sig { returns(T::Boolean) }
     def self.sdk_root_needed?
+      # odeprecated "`MacOS.sdk_root_needed?` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
       if MacOS::CLT.installed?
         # If there's no CLT SDK, return false
         return false unless MacOS::CLT.provides_sdk?
@@ -131,11 +139,13 @@ def self.sdk_for_formula(formula, version = nil, check_only_runtime_requirements
 
     # Returns the path to an SDK or nil, following the rules set by {sdk}.
     def self.sdk_path(version = nil)
+      # odeprecated "`MacOS.sdk_path` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
       s = sdk(version)
       s&.path
     end
 
     def self.sdk_path_if_needed(version = nil)
+      # odeprecated "`MacOS.sdk_path_if_needed` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
       # Prefer CLT SDK when both Xcode and the CLT are installed.
       # Expected results:
       # 1. On Xcode-only systems, return the Xcode SDK.

Library/Homebrew/os/mac/xcode.rb

@@ -126,6 +126,7 @@ def self.bundle_path
 
       sig { returns(T::Boolean) }
       def self.installed?
+        # odeprecated "`MacOS::Xcode.installed?` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
         !prefix.nil?
       end
 
@@ -174,6 +175,7 @@ def self.update_instructions
 
       sig { returns(::Version) }
       def self.version
+        # odeprecated "`MacOS::Xcode.version` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
         # may return a version string
         # that is guessed based on the compiler, so do not
         # use it in order to check if Xcode is installed.
@@ -264,6 +266,7 @@ module CLT
       # Returns true even if outdated tools are installed.
       sig { returns(T::Boolean) }
       def self.installed?
+        # odeprecated "`MacOS::CLT.installed?` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
         !version.null?
       end
 
@@ -397,6 +400,7 @@ def self.detect_version_from_clang_version
       # version numbers.
       sig { returns(::Version) }
       def self.version
+        # odeprecated "`MacOS::CLT.version` on Linux" if Homebrew::SimulateSystem.simulating_or_running_on_linux?
         if @version ||= detect_version
           ::Version.new @version
         else

Library/Homebrew/readall.rb

@@ -11,6 +11,10 @@ module Readall
   class << self
     include Cachable
 
+    # TODO: remove this once the `MacOS` module is undefined on Linux
+    MACOS_MODULE_REGEX = /\b(MacOS|OS::Mac)(\.|::)\b/.freeze
+    private_constant :MACOS_MODULE_REGEX
+
     private :cache
 
     def valid_ruby_syntax?(ruby_files)
@@ -59,7 +63,9 @@ def valid_formulae?(tap, bottle_tag: nil)
                                                        flags: [], ignore_errors: false)
         readall_formula = readall_formula_class.new(formula_name, file, :stable, tap: tap)
         readall_formula.to_hash
-        cache[:valid_formulae][file] = if readall_formula.on_system_blocks_exist?
+        # TODO: Remove check for MACOS_MODULE_REGEX once the `MacOS` module is undefined on Linux
+        cache[:valid_formulae][file] = if readall_formula.on_system_blocks_exist? ||
+                                          formula_contents.match?(MACOS_MODULE_REGEX)
           [bottle_tag, *cache[:valid_formulae][file]]
         else
           true

Library/Homebrew/rubocops/lines.rb

@@ -441,6 +441,21 @@ def audit_formula(_node, _class_node, _parent_class_node, body_node)
         end
       end
 
+      # This cop makes sure the `MacOS` module is not used in Linux-facing formula code
+      #
+      # @api private
+      class MacOSOnLinux < FormulaCop
+        include OnSystemConditionalsHelper
+
+        ON_MACOS_BLOCKS = [:macos, *MACOS_VERSION_OPTIONS].map { |os| :"on_#{os}" }.freeze
+
+        def audit_formula(_node, _class_node, _parent_class_node, body_node)
+          audit_macos_references(body_node,
+                                 allowed_methods: OnSystemConditionals::NO_ON_SYSTEM_METHOD_NAMES,
+                                 allowed_blocks:  OnSystemConditionals::NO_ON_SYSTEM_BLOCK_NAMES + ON_MACOS_BLOCKS)
+        end
+      end
+
       # This cop makes sure that the `generate_completions_from_executable` DSL is used.
       #
       # @api private