From dcba99c7d132efb310ecf61eec717177cbacf7b9 Mon Sep 17 00:00:00 2001
From: Mike McQuaid <mike@mikemcquaid.com>
Date: Mon, 2 Nov 2020 11:20:09 +0000
Subject: [PATCH] Revert "Revert "Improve @-versioned formulae linking.""

---
 Library/Homebrew/cmd/link.rb          | 24 +++++++++++----------
 Library/Homebrew/cmd/switch.rb        |  3 +++
 Library/Homebrew/cmd/unlink.rb        |  7 ++-----
 Library/Homebrew/formula.rb           |  8 +++----
 Library/Homebrew/formula_installer.rb |  3 +++
 Library/Homebrew/keg.rb               |  2 ++
 Library/Homebrew/unlink.rb            | 30 +++++++++++++++++++++++++++
 docs/Manpage.md                       |  4 ----
 manpages/brew.1                       |  3 ---
 9 files changed, 57 insertions(+), 27 deletions(-)
 create mode 100644 Library/Homebrew/unlink.rb

diff --git a/Library/Homebrew/cmd/link.rb b/Library/Homebrew/cmd/link.rb
index ad48c17792..f84fa9411d 100644
--- a/Library/Homebrew/cmd/link.rb
+++ b/Library/Homebrew/cmd/link.rb
@@ -4,6 +4,7 @@
 require "ostruct"
 require "caveats"
 require "cli/parser"
+require "unlink"
 
 module Homebrew
   module_function
@@ -66,26 +67,27 @@ module Homebrew
         next
       end
 
+      formula = keg.to_formula
+
       if keg_only
-        if Homebrew.default_prefix?
-          f = keg.to_formula
-          if f.keg_only_reason.by_macos?
-            caveats = Caveats.new(f)
-            opoo <<~EOS
-              Refusing to link macOS provided/shadowed software: #{keg.name}
-              #{caveats.keg_only_text(skip_reason: true).strip}
-            EOS
-            next
-          end
+        if Homebrew.default_prefix? && formula.keg_only_reason.by_macos?
+          caveats = Caveats.new(formula)
+          opoo <<~EOS
+            Refusing to link macOS provided/shadowed software: #{keg.name}
+            #{caveats.keg_only_text(skip_reason: true).strip}
+          EOS
+          next
         end
 
-        unless args.force?
+        if !formula.keg_only_reason.versioned_formula? && !args.force?
           opoo "#{keg.name} is keg-only and must be linked with --force"
           puts_keg_only_path_message(keg)
           next
         end
       end
 
+      Unlink.unlink_versioned_formulae(formula, verbose: args.verbose?)
+
       keg.lock do
         print "Linking #{keg}... "
         puts if args.verbose?
diff --git a/Library/Homebrew/cmd/switch.rb b/Library/Homebrew/cmd/switch.rb
index 94389f2b8e..0877f51d09 100644
--- a/Library/Homebrew/cmd/switch.rb
+++ b/Library/Homebrew/cmd/switch.rb
@@ -17,6 +17,7 @@ module Homebrew
       EOS
 
       named 2
+      hide_from_man_page!
     end
   end
 
@@ -28,6 +29,8 @@ module Homebrew
 
     odie "#{name} not found in the Cellar." unless rack.directory?
 
+    # odeprecated "`brew switch`", "`brew link` @-versioned formulae"
+
     versions = rack.subdirs
                    .map { |d| Keg.new(d).version }
                    .sort
diff --git a/Library/Homebrew/cmd/unlink.rb b/Library/Homebrew/cmd/unlink.rb
index 080bcd1636..2abbc3d947 100644
--- a/Library/Homebrew/cmd/unlink.rb
+++ b/Library/Homebrew/cmd/unlink.rb
@@ -3,6 +3,7 @@
 
 require "ostruct"
 require "cli/parser"
+require "unlink"
 
 module Homebrew
   module_function
@@ -36,11 +37,7 @@ module Homebrew
         next
       end
 
-      keg.lock do
-        print "Unlinking #{keg}... "
-        puts if args.verbose?
-        puts "#{keg.unlink(**options)} symlinks removed"
-      end
+      Unlink.unlink(keg, dry_run: args.dry_run?, verbose: args.verbose?)
     end
   end
 end
diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index 6812b905f4..5dd79b65dd 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -414,12 +414,12 @@ class Formula
     name.include?("@")
   end
 
-  # Returns any `@`-versioned formulae for an non-`@`-versioned formula.
+  # Returns any `@`-versioned formulae for any formula (including versioned formulae).
   def versioned_formulae
-    return [] if versioned_formula?
+    Pathname.glob(path.to_s.gsub(/(@[\d.]+)?\.rb$/, "@*.rb")).map do |versioned_path|
+      next if versioned_path == path
 
-    Pathname.glob(path.to_s.gsub(/\.rb$/, "@*.rb")).map do |path|
-      Formula[path.basename(".rb").to_s]
+      Formula[versioned_path.basename(".rb").to_s]
     rescue FormulaUnavailableError
       nil
     end.compact.sort_by(&:version).reverse
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index c9a29c3315..57aedf4434 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -22,6 +22,7 @@ require "cmd/install"
 require "find"
 require "utils/spdx"
 require "deprecate_disable"
+require "unlink"
 
 # Installer for a formula.
 #
@@ -884,6 +885,8 @@ class FormulaInstaller
       keg.remove_linked_keg_record
     end
 
+    Homebrew::Unlink.unlink_versioned_formulae(formula, verbose: verbose?)
+
     link_overwrite_backup = {} # Hash: conflict file -> backup file
     backup_dir = HOMEBREW_CACHE/"Backup"
 
diff --git a/Library/Homebrew/keg.rb b/Library/Homebrew/keg.rb
index 902ed12f38..a06ac9617f 100644
--- a/Library/Homebrew/keg.rb
+++ b/Library/Homebrew/keg.rb
@@ -335,6 +335,7 @@ class Keg
     EOS
   end
 
+  # TODO: refactor to use keyword arguments.
   def unlink(**options)
     ObserverPathnameExtension.reset_counts!
 
@@ -448,6 +449,7 @@ class Keg
     end
   end
 
+  # TODO: refactor to use keyword arguments.
   def link(**options)
     raise AlreadyLinkedError, self if linked_keg_record.directory?
 
diff --git a/Library/Homebrew/unlink.rb b/Library/Homebrew/unlink.rb
new file mode 100644
index 0000000000..bd265d5c5c
--- /dev/null
+++ b/Library/Homebrew/unlink.rb
@@ -0,0 +1,30 @@
+# typed: false
+# frozen_string_literal: true
+
+module Homebrew
+  # Provides helper methods for unlinking formulae and kegs with consistent output.
+  module Unlink
+    module_function
+
+    def unlink_versioned_formulae(formula, verbose: false)
+      formula.versioned_formulae
+             .select(&:linked?)
+             .map(&:any_installed_keg)
+             .compact
+             .select(&:directory?)
+             .each do |keg|
+        unlink(keg, verbose: verbose)
+      end
+    end
+
+    def unlink(keg, dry_run: false, verbose: false)
+      options = { dry_run: dry_run, verbose: verbose }
+
+      keg.lock do
+        print "Unlinking #{keg}... "
+        puts if verbose
+        puts "#{keg.unlink(**options)} symlinks removed"
+      end
+    end
+  end
+end
diff --git a/docs/Manpage.md b/docs/Manpage.md
index d3cbe3eeb5..f6f194eb7d 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -537,10 +537,6 @@ Print export statements. When run in a shell, this installation of Homebrew will
 The variables `HOMEBREW_PREFIX`, `HOMEBREW_CELLAR` and `HOMEBREW_REPOSITORY` are also exported to avoid querying them multiple times.
 Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`) with: `eval $(brew shellenv)`
 
-### `switch` *`formula`* *`version`*
-
-Symlink all of the specified *`version`* of *`formula`*'s installation into Homebrew's prefix.
-
 ### `tap` [*`options`*] [*`user`*`/`*`repo`*] [*`URL`*]
 
 Tap a formula repository.
diff --git a/manpages/brew.1 b/manpages/brew.1
index 394ee5589f..dd87f709ac 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -773,9 +773,6 @@ Print export statements\. When run in a shell, this installation of Homebrew wil
 .P
 The variables \fBHOMEBREW_PREFIX\fR, \fBHOMEBREW_CELLAR\fR and \fBHOMEBREW_REPOSITORY\fR are also exported to avoid querying them multiple times\. Consider adding evaluation of this command\'s output to your dotfiles (e\.g\. \fB~/\.profile\fR, \fB~/\.bash_profile\fR, or \fB~/\.zprofile\fR) with: \fBeval $(brew shellenv)\fR
 .
-.SS "\fBswitch\fR \fIformula\fR \fIversion\fR"
-Symlink all of the specified \fIversion\fR of \fIformula\fR\'s installation into Homebrew\'s prefix\.
-.
 .SS "\fBtap\fR [\fIoptions\fR] [\fIuser\fR\fB/\fR\fIrepo\fR] [\fIURL\fR]"
 Tap a formula repository\.
 .