1 files changed, 14 insertions, 0 deletions
diff --git a/lib/rubygems/specification_policy.rb b/lib/rubygems/specification_policy.rb
index e830d9af48..3a30750056 100644
--- a/lib/rubygems/specification_policy.rb
+++ b/lib/rubygems/specification_policy.rb
@@ -1,3 +1,4 @@
+require 'rubygems/ext'
 require 'rubygems/user_interaction'
 
 class Gem::SpecificationPolicy
@@ -76,6 +77,8 @@ class Gem::SpecificationPolicy
 
     validate_dependencies
 
+    validate_extensions
+
     validate_removed_attributes
 
     if @warnings > 0
@@ -417,6 +420,17 @@ http://spdx.org/licenses or '#{Gem::Licenses::NONSTANDARD}' for a nonstandard li
     end
   end
 
+  def validate_extensions # :nodoc:
+    builder = Gem::Ext::Builder.new(@specification)
+
+    rake_extension = @specification.extensions.any? {|s| builder.builder_for(s) == Gem::Ext::RakeBuilder }
+    rake_dependency = @specification.dependencies.any? {|d| d.name == 'rake'}
+
+    warning <<-WARNING if rake_extension && !rake_dependency
+You have specified rake based extension, but rake is not added as dependency. It is recommended to add rake as a dependency since there's no guarantee rake will be already installed.
+    WARNING
+  end
+
   def warning(statement) # :nodoc:
     @warnings += 1