outdated: check if formula needs to be migrated.

Closes Homebrew/homebrew#42938.

1 files changed, 8 insertions, 0 deletions

diff --git a/Library/Homebrew/cmd/outdated.rb b/Library/Homebrew/cmd/outdated.rb
index 673ea966c..45e195939 100644
--- a/Library/Homebrew/cmd/outdated.rb
+++ b/Library/Homebrew/cmd/outdated.rb
@@ -1,5 +1,6 @@
 require "formula"
 require "keg"
+require "migrator"
 
 module Homebrew
   def outdated
@@ -16,6 +17,13 @@ module Homebrew
     formulae.map do |f|
       all_versions = []
       older_or_same_tap_versions = []
+
+      if f.oldname && !f.rack.exist?
+        if Pathname.new("#{HOMEBREW_CELLAR}/#{f.oldname}").exist?
+          raise Migrator::MigrationNeededError.new(f)
+        end
+      end
+
       f.rack.subdirs.each do |dir|
         keg = Keg.new dir
         version = keg.version