Rails 5 fix for keeping query parameters in pagination links

In Rails 5, `params` hash is no longer a simple
HashWithIndifferentAccess, but an ActionController::Parameters instance
with implements the "strong parameters" concept that prevents mass
assignment.

Fixes #501, closes #502, fixes #486, closes #483

lib/will_paginate/view_helpers/link_renderer.rb

@@ -115,12 +115,12 @@ def rel_value(page)
       end
 
       def symbolized_update(target, other, blacklist = nil)
-        other.each do |key, value|
+        other.each_pair do |key, value|
           key = key.to_sym
           existing = target[key]
           next if blacklist && blacklist.include?(key)
 
-          if value.is_a?(Hash) and (existing.is_a?(Hash) or existing.nil?)
+          if value.respond_to?(:each_pair) and (existing.is_a?(Hash) or existing.nil?)
             symbolized_update(existing || (target[key] = {}), value)
           else
             target[key] = value

spec/view_helpers/action_view_spec.rb

@@ -416,7 +416,7 @@ class DummyRequest
   def initialize(controller)
     @controller = controller
     @get = true
-    @params = {}
+    @params = {}.with_indifferent_access
     @symbolized_path_parameters = { :controller => 'foo', :action => 'bar' }
   end
 
@@ -442,7 +442,11 @@ def script_name
 
   def params(more = nil)
     @params.update(more) if more
-    @params
+    if defined?(ActionController::Parameters)
+      ActionController::Parameters.new(@params)
+    else
+      @params
+    end
   end
 
   def host_with_port
@@ -458,3 +462,7 @@ def protocol
     'http:'
   end
 end
+
+if defined?(ActionController::Parameters)
+  ActionController::Parameters.permit_all_parameters = false
+end