Consolidate shared install and upgrade logic

Library/Homebrew/install.rb

@@ -5,6 +5,7 @@ require "diagnostic"
 require "fileutils"
 require "hardware"
 require "development_tools"
+require "upgrade"
 
 module Homebrew
   # Helper module for performing (pre-)install checks.
@@ -249,20 +250,6 @@ module Homebrew
       f.print_tap_action
       build_options = f.build
 
-      if !Homebrew::EnvConfig.no_install_upgrade? && f.outdated? && !f.head?
-        outdated_formulae = [f, *f.old_installed_formulae]
-        version_upgrade = "#{f.linked_version} -> #{f.pkg_version}"
-
-        oh1 <<~EOS
-          #{f.name} #{f.linked_version} is installed but outdated
-            Upgrading #{Formatter.identifier(f.name)} #{version_upgrade}
-        EOS
-        outdated_kegs = outdated_formulae.map(&:linked_keg)
-                                         .select(&:directory?)
-                                         .map { |k| Keg.new(k.resolved_path) }
-        linked_kegs = outdated_kegs.select(&:linked?)
-      end
-
       fi = FormulaInstaller.new(
         f,
         options:                    build_options.used_options,
@@ -282,10 +269,17 @@ module Homebrew
         quiet:                      quiet,
         verbose:                    verbose,
       )
+
+      if !Homebrew::EnvConfig.no_install_upgrade? && f.outdated? && !f.head?
+        kegs = Upgrade.outdated_kegs(f)
+        linked_kegs = kegs.select(&:linked?)
+        Upgrade.print_upgrade_message(f, fi.options)
+      end
+
       fi.prelude
       fi.fetch
 
-      outdated_kegs.each(&:unlink) if outdated_kegs.present?
+      kegs.each(&:unlink) if kegs.present?
 
       fi.install
       fi.finish

Library/Homebrew/upgrade.rb

@@ -64,6 +64,24 @@ module Homebrew
       end
     end
 
+    def outdated_kegs(formula)
+      [formula, *formula.old_installed_formulae].map(&:linked_keg)
+                                                .select(&:directory?)
+                                                .map { |k| Keg.new(k.resolved_path) }
+    end
+
+    def print_upgrade_message(formula, fi_options)
+      version_upgrade = if formula.optlinked?
+        "#{Keg.new(formula.opt_prefix).version} -> #{formula.pkg_version}"
+      else
+        "-> #{formula.pkg_version}"
+      end
+      oh1 <<~EOS
+        Upgrading #{Formatter.identifier(formula.full_specified_name)}
+          #{version_upgrade} #{fi_options.to_a.join(" ")}
+      EOS
+    end
+
     def upgrade_formula(
       formula,
       flags:,
@@ -83,11 +101,8 @@ module Homebrew
         keg_was_linked = keg.linked?
       end
 
-      formulae_maybe_with_kegs = [formula] + formula.old_installed_formulae
+      kegs = outdated_kegs(formula)
-      outdated_kegs = formulae_maybe_with_kegs.map(&:linked_keg)
+      linked_kegs = kegs.select(&:linked?)
-                                              .select(&:directory?)
-                                              .map { |k| Keg.new(k.resolved_path) }
-      linked_kegs = outdated_kegs.select(&:linked?)
 
       if formula.opt_prefix.directory?
         keg = Keg.new(formula.opt_prefix.resolved_path)
@@ -118,13 +133,7 @@ module Homebrew
         }.compact,
       )
 
-      upgrade_version = if formula.optlinked?
+      print_upgrade_message(formula, fi.options)
-        "#{Keg.new(formula.opt_prefix).version} -> #{formula.pkg_version}"
-      else
-        "-> #{formula.pkg_version}"
-      end
-      oh1 "Upgrading #{Formatter.identifier(formula.full_specified_name)} " \
-          "#{upgrade_version} #{fi.options.to_a.join(" ")}"
 
       fi.prelude
       fi.fetch
@@ -132,7 +141,7 @@ module Homebrew
       # first we unlink the currently active keg for this formula otherwise it is
       # possible for the existing build to interfere with the build we are about to
       # do! Seriously, it happens!
-      outdated_kegs.each(&:unlink)
+      kegs.each(&:unlink)
 
       fi.install
       fi.finish