linux: use preferred_gcc instead of gcc

Library/Homebrew/compilers.rb

@@ -110,16 +110,16 @@ class CompilerSelector
     raise CompilerSelectionError, formula
   end
 
-  private
-
   sig { returns(String) }
-  def preferred_gcc
+  def self.preferred_gcc
     "gcc"
   end
 
+  private
+
   def gnu_gcc_versions
     # prioritize gcc version provided by gcc formula.
-    v = Formulary.factory(preferred_gcc).version.to_s.slice(/\d+/)
+    v = Formulary.factory(CompilerSelector.preferred_gcc).version.to_s.slice(/\d+/)
     GNU_GCC_VERSIONS - [v] + [v] # move the version to the end of the list
   rescue FormulaUnavailableError
     GNU_GCC_VERSIONS

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

@@ -3,7 +3,7 @@
 
 class CompilerSelector
   sig { returns(String) }
-  def preferred_gcc
+  def self.preferred_gcc
     # gcc-5 is the lowest gcc version we support on Linux.
     # gcc-5 is the default gcc in Ubuntu 16.04 (used for our CI)
     "gcc@5"

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

 # typed: true
 # frozen_string_literal: true
 
+require "compilers"
+
 class Keg
   def relocate_dynamic_linkage(relocation)
     # Patching the dynamic linker of glibc breaks it.
@@ -84,7 +86,7 @@ class Keg
   def self.bottle_dependencies
     @bottle_dependencies ||= begin
       formulae = relocation_formulae
-      gcc = Formula["gcc"]
+      gcc = Formulary.factory(CompilerSelector.preferred_gcc)
       if !Homebrew::EnvConfig.force_homebrew_on_linux? &&
          DevelopmentTools.non_apple_gcc_version("gcc") < gcc.version.to_i
         formulae += gcc.recursive_dependencies.map(&:name)

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

 # typed: true
 # frozen_string_literal: true
 
+require "compilers"
+
 class LinkageChecker
   # Libraries provided by glibc and gcc.
   SYSTEM_LIBRARY_ALLOWLIST = %w[
@@ -30,6 +32,6 @@ class LinkageChecker
     @unwanted_system_dylibs = @system_dylibs.reject do |s|
       SYSTEM_LIBRARY_ALLOWLIST.include? File.basename(s)
     end
-    @undeclared_deps -= ["gcc", "glibc"]
+    @undeclared_deps -= [CompilerSelector.preferred_gcc, "glibc"]
   end
 end

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

 # typed: true
 # frozen_string_literal: true
 
+require "compilers"
 require "os/linux/glibc"
 require "system_command"
 
@@ -46,7 +47,7 @@ module SystemConfig
       out.puts "Host glibc: #{host_glibc_version}"
       out.puts "/usr/bin/gcc: #{host_gcc_version}"
       out.puts "/usr/bin/ruby: #{host_ruby_version}" if RUBY_PATH != HOST_RUBY_PATH
-      ["glibc", "gcc", "xorg"].each do |f|
+      ["glibc", CompilerSelector.preferred_gcc, "xorg"].each do |f|
         out.puts "#{f}: #{formula_linked_version(f)}"
       end
     end

Library/Homebrew/test/formula_installer_bottle_spec.rb

@@ -24,6 +24,7 @@ describe FormulaInstaller do
 
     stub_formula_loader formula
     stub_formula_loader formula("gcc") { url "gcc-1.0" }
+    stub_formula_loader formula("gcc@5") { url "gcc-5.0" }
     stub_formula_loader formula("patchelf") { url "patchelf-1.0" }
     allow(Formula["patchelf"]).to receive(:latest_version_installed?).and_return(true)
 

Library/Homebrew/test/formulary_spec.rb

@@ -142,6 +142,7 @@ describe Formulary do
       before do
         allow(described_class).to receive(:loader_for).and_call_original
         stub_formula_loader formula("gcc") { url "gcc-1.0" }
+        stub_formula_loader formula("gcc@5") { url "gcc-5.0" }
         stub_formula_loader formula("patchelf") { url "patchelf-1.0" }
         allow(Formula["patchelf"]).to receive(:latest_version_installed?).and_return(true)
       end