Make RAILS_* give deprecation warning just once

railties/lib/rails/deprecation.rb

@@ -2,6 +2,9 @@
 require "active_support/deprecation"
 
 RAILS_ROOT = (Class.new(ActiveSupport::Deprecation::DeprecationProxy) do
+  cattr_accessor :warned
+  self.warned = false
+
   def target
     Rails.root
   end
@@ -11,12 +14,17 @@ def replace(*args)
   end
 
   def warn(callstack, called, args)
-    msg = "RAILS_ROOT is deprecated! Use Rails.root instead"
-    ActiveSupport::Deprecation.warn(msg, callstack)
+    unless warned
+      ActiveSupport::Deprecation.warn("RAILS_ROOT is deprecated! Use Rails.root instead", callstack)
+      self.warned = true
+    end
   end
 end).new
 
 RAILS_ENV = (Class.new(ActiveSupport::Deprecation::DeprecationProxy) do
+  cattr_accessor :warned
+  self.warned = false
+
   def target
     Rails.env
   end
@@ -26,12 +34,17 @@ def replace(*args)
   end
 
   def warn(callstack, called, args)
-    msg = "RAILS_ENV is deprecated! Use Rails.env instead"
-    ActiveSupport::Deprecation.warn(msg, callstack)
+    unless warned
+      ActiveSupport::Deprecation.warn("RAILS_ENV is deprecated! Use Rails.env instead", callstack)
+      self.warned = true
+    end
   end
 end).new
 
 RAILS_DEFAULT_LOGGER = (Class.new(ActiveSupport::Deprecation::DeprecationProxy) do
+  cattr_accessor :warned
+  self.warned = false
+
   def target
     Rails.logger
   end
@@ -41,7 +54,9 @@ def replace(*args)
   end
 
   def warn(callstack, called, args)
-    msg = "RAILS_DEFAULT_LOGGER is deprecated! Use Rails.logger instead"
-    ActiveSupport::Deprecation.warn(msg, callstack)
+    unless warned
+      ActiveSupport::Deprecation.warn("RAILS_DEFAULT_LOGGER is deprecated! Use Rails.logger instead", callstack)
+      self.warned = true
+    end
   end
 end).new