Ruby 1.9.2: disallow explicit coercion via method_missing. Only give friendly nil errors for Array and Active Record methods.

activesupport/lib/active_support/core_ext/name_error.rb

@@ -1,7 +1,9 @@
 class NameError
   # Extract the name of the missing constant from the exception message.
   def missing_name
-    $1 if /((::)?([A-Z]\w*)(::[A-Z]\w*)*)$/ =~ message
+    if /undefined local variable or method/ !~ message
+      $1 if /((::)?([A-Z]\w*)(::[A-Z]\w*)*)$/ =~ message
+    end
   end
 
   # Was this exception raised because the given name was missing?

activesupport/lib/active_support/whiny_nil.rb

@@ -43,7 +43,14 @@ class NilClass
 
   private
     def method_missing(method, *args, &block)
-      raise_nil_warning_for METHOD_CLASS_MAP[method], method, caller
+      # Ruby 1.9.2: disallow explicit coercion via method_missing.
+      if method == :to_ary || method == :to_str
+        super
+      elsif klass = METHOD_CLASS_MAP[method]
+        raise_nil_warning_for klass, method, caller
+      else
+        super
+      end
     end
 
     # Raises a NoMethodError when you attempt to call a method on +nil+.
@@ -55,4 +62,3 @@ class NilClass
       raise NoMethodError, message, with_caller || caller
     end
 end
-

activesupport/test/core_ext/name_error_test.rb

@@ -3,23 +3,19 @@ require 'active_support/core_ext/name_error'
 
 class NameErrorTest < Test::Unit::TestCase
   def test_name_error_should_set_missing_name
-    begin
-      SomeNameThatNobodyWillUse____Really ? 1 : 0
-      flunk "?!?!"
-    rescue NameError => exc
-      assert_equal "NameErrorTest::SomeNameThatNobodyWillUse____Really", exc.missing_name
-      assert exc.missing_name?(:SomeNameThatNobodyWillUse____Really)
-      assert exc.missing_name?("NameErrorTest::SomeNameThatNobodyWillUse____Really")
-    end
+    SomeNameThatNobodyWillUse____Really ? 1 : 0
+    flunk "?!?!"
+  rescue NameError => exc
+    assert_equal "NameErrorTest::SomeNameThatNobodyWillUse____Really", exc.missing_name
+    assert exc.missing_name?(:SomeNameThatNobodyWillUse____Really)
+    assert exc.missing_name?("NameErrorTest::SomeNameThatNobodyWillUse____Really")
   end
 
   def test_missing_method_should_ignore_missing_name
-    begin
-      some_method_that_does_not_exist
-      flunk "?!?!"
-    rescue NameError => exc
-      assert_equal nil, exc.missing_name
-      assert ! exc.missing_name?(:Foo)
-    end
+    some_method_that_does_not_exist
+    flunk "?!?!"
+  rescue NameError => exc
+    assert !exc.missing_name?(:Foo)
+    assert_nil exc.missing_name
   end
 end

activesupport/test/whiny_nil_test.rb

@@ -13,7 +13,7 @@ class WhinyNilTest < Test::Unit::TestCase
   def test_unchanged
     nil.method_thats_not_in_whiners
   rescue NoMethodError => nme
-    assert_match(/nil.method_thats_not_in_whiners/, nme.message)
+    assert(nme.message =~ /nil:NilClass/)
   end
 
   def test_active_record
@@ -35,4 +35,16 @@ class WhinyNilTest < Test::Unit::TestCase
   rescue RuntimeError => nme
     assert(!(nme.message =~ /nil:NilClass/))
   end
+
+  def test_no_to_ary_coercion
+    nil.to_ary
+  rescue NoMethodError => nme
+    assert(nme.message =~ /nil:NilClass/)
+  end
+
+  def test_no_to_str_coercion
+    nil.to_str
+  rescue NoMethodError => nme
+    assert(nme.message =~ /nil:NilClass/)
+  end
 end