1 files changed, 29 insertions, 12 deletions

diff --git a/activesupport/lib/active_support/dependencies.rb b/activesupport/lib/active_support/dependencies.rb
index fff4c776a9..6be19771f5 100644
--- a/activesupport/lib/active_support/dependencies.rb
+++ b/activesupport/lib/active_support/dependencies.rb
@@ -8,6 +8,7 @@ require 'active_support/core_ext/module/introspection'
 require 'active_support/core_ext/module/anonymous'
 require 'active_support/core_ext/module/qualified_const'
 require 'active_support/core_ext/object/blank'
+require 'active_support/core_ext/kernel/reporting'
 require 'active_support/core_ext/load_error'
 require 'active_support/core_ext/name_error'
 require 'active_support/core_ext/string/starts_ends_with'
@@ -175,14 +176,22 @@ module ActiveSupport #:nodoc:
       end
 
       def const_missing(const_name)
-        # The interpreter does not pass nesting information, and in the
-        # case of anonymous modules we cannot even make the trade-off of
-        # assuming their name reflects the nesting. Resort to Object as
-        # the only meaningful guess we can make.
-        from_mod = anonymous? ? ::Object : self
+        from_mod = anonymous? ? guess_for_anonymous(const_name) : self
         Dependencies.load_missing_constant(from_mod, const_name)
       end
 
+      # Dependencies assumes the name of the module reflects the nesting (unless
+      # it can be proven that is not the case), and the path to the file that
+      # defines the constant. Anonymous modules cannot follow these conventions
+      # and we assume therefore the user wants to refer to a top-level constant.
+      def guess_for_anonymous(const_name)
+        if Object.const_defined?(const_name)
+          raise NameError, "#{const_name} cannot be autoloaded from an anonymous class or module"
+        else
+          Object
+        end
+      end
+
       def unloadable(const_desc = self)
         super(const_desc)
       end
@@ -198,9 +207,19 @@ module ActiveSupport #:nodoc:
         Dependencies.require_or_load(file_name)
       end
 
+      # Interprets a file using <tt>mechanism</tt> and marks its defined
+      # constants as autoloaded. <tt>file_name</tt> can be either a string or
+      # respond to <tt>to_path</tt>.
+      #
+      # Use this method in code that absolutely needs a certain constant to be
+      # defined at that point. A typical use case is to make constant name
+      # resolution deterministic for constants with the same relative name in
+      # different namespaces whose evaluation would depend on load order
+      # otherwise.
       def require_dependency(file_name, message = "No such file to load -- %s")
+        file_name = file_name.to_path if file_name.respond_to?(:to_path)
         unless file_name.is_a?(String)
-          raise ArgumentError, "the file name must be a String -- you passed #{file_name.inspect}"
+          raise ArgumentError, "the file name must either be a String or implement #to_path -- you passed #{file_name.inspect}"
         end
 
         Dependencies.depend_on(file_name, message)
@@ -213,7 +232,7 @@ module ActiveSupport #:nodoc:
           yield
         end
       rescue Exception => exception  # errors from loading file
-        exception.blame_file! file
+        exception.blame_file! file if exception.respond_to? :blame_file!
         raise
       end
 
@@ -416,7 +435,7 @@ module ActiveSupport #:nodoc:
     def load_file(path, const_paths = loadable_constants_for_path(path))
       log_call path, const_paths
       const_paths = [const_paths].compact unless const_paths.is_a? Array
-      parent_paths = const_paths.collect { |const_path| const_path[/.*(?=::)/] || :Object }
+      parent_paths = const_paths.collect { |const_path| const_path[/.*(?=::)/] || ::Object }
 
       result = nil
       newly_defined_paths = new_constants_in(*parent_paths) do
@@ -445,8 +464,6 @@ module ActiveSupport #:nodoc:
         raise ArgumentError, "A copy of #{from_mod} has been removed from the module tree but is still active!"
       end
 
-      raise NameError, "#{from_mod} is not missing constant #{const_name}!" if from_mod.const_defined?(const_name, false)
-
       qualified_name = qualified_name_for from_mod, const_name
       path_suffix = qualified_name.underscore
 
@@ -459,7 +476,7 @@ module ActiveSupport #:nodoc:
         if loaded.include?(expanded)
           raise "Circular dependency detected while autoloading constant #{qualified_name}"
         else
-          require_or_load(expanded)
+          require_or_load(expanded, qualified_name)
           raise LoadError, "Unable to autoload constant #{qualified_name}, expected #{file_path} to define it" unless from_mod.const_defined?(const_name, false)
           return from_mod.const_get(const_name)
         end
@@ -634,7 +651,7 @@ module ActiveSupport #:nodoc:
         when String then desc.sub(/^::/, '')
         when Symbol then desc.to_s
         when Module
-          desc.name.presence ||
+          desc.name ||
             raise(ArgumentError, "Anonymous modules have no name to be referenced by")
         else raise TypeError, "Not a valid constant descriptor: #{desc.inspect}"
       end