Implement warnings for {Module,Proc}#ruby2_keywords

Author: eregon

spec/tags/core/module/ruby2_keywords_tags.txt

@@ -1,8 +1,3 @@
 fails:Module#ruby2_keywords marks the final hash argument as keyword hash
 fails:Module#ruby2_keywords fixes delegation warnings when calling a method accepting keywords
-fails:Module#ruby2_keywords raises NameError when passed not existing method name
 fails:Module#ruby2_keywords acceps String as well
-fails:Module#ruby2_keywords raises TypeError when passed not Symbol or String
-fails:Module#ruby2_keywords prints warning when a method does not accept argument splat
-fails:Module#ruby2_keywords prints warning when a method accepts keywords
-fails:Module#ruby2_keywords prints warning when a method accepts keyword splat

spec/tags/core/proc/ruby2_keywords_tags.txt

@@ -1,6 +1,3 @@
 fails:Proc#ruby2_keywords marks the final hash argument as keyword hash
 fails:Proc#ruby2_keywords fixes delegation warnings when calling a method accepting keywords
 fails:Proc#ruby2_keywords fixes delegation warnings when calling a proc accepting keywords
-fails:Proc#ruby2_keywords prints warning when a proc does not accept argument splat
-fails:Proc#ruby2_keywords prints warning when a proc accepts keywords
-fails:Proc#ruby2_keywords prints warning when a proc accepts keyword splat

src/main/ruby/truffleruby/core/pre.rb

@@ -45,13 +45,28 @@ def include(mod)
   end
 
   private def ruby2_keywords(*methods)
+    methods.each do |name|
+      method = instance_method(name)
+      kinds = method.parameters.map(&:first)
+      if !kinds.include?(:rest)
+        warn "Skipping set of ruby2_keywords flag for #{name} (method does not accept argument splat)", uplevel: 1
+      elsif kinds.include?(:key) or kinds.include?(:keyreq) or kinds.include?(:keyrest)
+        warn "Skipping set of ruby2_keywords flag for #{name} (method accepts keywords)", uplevel: 1
+      end
+    end
     warn "ruby2_keywords(#{methods.join(', ')}) was ignored", uplevel: 1 if $DEBUG
     nil
   end
 end
 
 class Proc
   def ruby2_keywords
+    kinds = parameters.map(&:first)
+    if !kinds.include?(:rest)
+      warn 'Skipping set of ruby2_keywords flag for proc (proc does not accept argument splat)', uplevel: 1
+    elsif kinds.include?(:key) or kinds.include?(:keyreq) or kinds.include?(:keyrest)
+      warn 'Skipping set of ruby2_keywords flag for proc (proc accepts keywords)', uplevel: 1
+    end
     warn 'Proc#ruby2_keywords was ignored', uplevel: 1 if $DEBUG
     self
   end