brew-pin: prevent selected formulae from upgrade.

* Added `pin` et. al. to manpage.
* Added `brew pin` to `brew.1` * Added `brew unpin` to `brew.1`
* Added `brew list --pinned` to `brew.1`
* Added information about frozen formulae to `brew upgrade` in `brew.1`
* Added `pin` et.al. to completion scripts.
* Unpin formulae when uninstalling them
* Unpin and re-pin formulae when upgrading (avoids stale symlink)

References #18386.
Closes #18515.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/Library/Homebrew/cmd/upgrade.rb b/Library/Homebrew/cmd/upgrade.rb
index b5effee50..af2e4a0e1 100644
--- a/Library/Homebrew/cmd/upgrade.rb
+++ b/Library/Homebrew/cmd/upgrade.rb
@@ -18,8 +18,10 @@ module Homebrew extend self
 
     if ARGV.named.empty?
       require 'cmd/outdated'
+      upgrade_pinned = false
       outdated = Homebrew.outdated_brews
     else
+      upgrade_pinned = true
       outdated = ARGV.formulae.select do |f|
         if f.installed?
           onoe "#{f}-#{f.installed_version} already installed"
@@ -32,10 +34,19 @@ module Homebrew extend self
       exit 1 if outdated.empty?
     end
 
-    if outdated.length > 1
+    unless upgrade_pinned
+      pinned = outdated.select { |f| f.pinned? }
+      outdated -= pinned
+    end
+
+    if outdated.length > 0
       oh1 "Upgrading #{outdated.length} outdated package#{outdated.length.plural_s}, with result:"
       puts outdated.map{ |f| "#{f.name} #{f.version}" } * ", "
     end
+    if not upgrade_pinned and pinned.length > 0
+      oh1 "Not upgrading #{pinned.length} pinned package#{outdated.length.plural_s}:"
+      puts pinned.map{ |f| "#{f.name} #{f.version}" } * ", "
+    end
 
     outdated.each do |f|
       upgrade_formula f
@@ -60,6 +71,13 @@ module Homebrew extend self
     installer.install
     installer.caveats
     installer.finish
+
+    # If the formula was pinned, and we were force-upgrading it, unpin and
+    # pin it again to get a symlink pointing to the correct keg.
+    if f.pinned?
+      f.unpin
+      f.pin
+    end
   rescue FormulaInstallationAlreadyAttemptedError
     # We already attempted to upgrade f as part of the dependency tree of
     # another formula. In that case, don't generate an error, just move on.