From 3e61e3b4288f7eabe4b7e894dc10df6eba270bf9 Mon Sep 17 00:00:00 2001
From: Markus Reiter <me@reitermark.us>
Date: Sat, 10 Feb 2024 14:56:53 +0100
Subject: [PATCH] Stop following recursive tap migrations.

---
 Library/Homebrew/cask/cask_loader.rb | 13 +++++++++----
 Library/Homebrew/formulary.rb        | 13 +++++++++----
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/Library/Homebrew/cask/cask_loader.rb b/Library/Homebrew/cask/cask_loader.rb
index cf2ac67abb..8f26061834 100644
--- a/Library/Homebrew/cask/cask_loader.rb
+++ b/Library/Homebrew/cask/cask_loader.rb
@@ -534,10 +534,15 @@ module Cask
         new_tap = Tap.fetch(new_tap_name)
         new_tap.ensure_installed!
         new_tapped_token = "#{new_tap_name}/#{token}"
-        token, tap, = tap_cask_token_type(new_tapped_token, warn: false)
-        old_token = tapped_token
-        new_token = new_tap.core_cask_tap? ? token : new_tapped_token
-        type = :migration
+
+        if tapped_token == new_tapped_token
+          opoo "Tap migration for #{tapped_token} points to itself, stopping recursion."
+        else
+          token, tap, = tap_cask_token_type(new_tapped_token, warn: false)
+          old_token = tapped_token
+          new_token = new_tap.core_cask_tap? ? token : new_tapped_token
+          type = :migration
+        end
       end
 
       opoo "Cask #{old_token} was renamed to #{new_token}." if warn && old_token && new_token
diff --git a/Library/Homebrew/formulary.rb b/Library/Homebrew/formulary.rb
index e12eb93962..19316cd98a 100644
--- a/Library/Homebrew/formulary.rb
+++ b/Library/Homebrew/formulary.rb
@@ -921,10 +921,15 @@ module Formulary
       new_tap = Tap.fetch new_tap_name
       new_tap.ensure_installed!
       new_tapped_name = "#{new_tap_name}/#{name}"
-      name, tap, = Formulary.tap_formula_name_type(new_tapped_name, warn: false)
-      old_name = tapped_name
-      new_name = new_tap.core_tap? ? name : new_tapped_name
-      type = :migration
+
+      if tapped_name == new_tapped_name
+        opoo "Tap migration for #{tapped_name} points to itself, stopping recursion."
+      else
+        name, tap, = tap_formula_name_type(new_tapped_name, warn: false)
+        old_name = tapped_name
+        new_name = new_tap.core_tap? ? name : new_tapped_name
+        type = :migration
+      end
     end
 
     opoo "Formula #{old_name} was renamed to #{new_name}." if warn && old_name && new_name