Fix recursive Data#inspect

Author: andrykonchin

CHANGELOG.md

@@ -23,6 +23,7 @@ Compatibility:
 * Fix `Kernel#raise` and don't override `cause` at exception re-raising (#3831, @andrykonchin).
 * Return a pointer with `#type_size` of 1 for `Pointer#read_pointer` (@eregon).
 * Fix `rb_str_locktmp()` and `rb_str_unlocktmp()` to raise `FrozenError` when string argument is frozen (#3752, @andrykonchin).
+* Fix `Data#inspect` when data contains a recursive attribute (#3847, @andrykonchin).
 
 Performance:
 

spec/ruby/core/data/shared/inspect.rb

@@ -50,5 +50,13 @@ def self.name
 
       a.send(@method).should == "#<data DataSpecs::Measure amount=42, unit=#<data DataSpecs::Measure:...>>"
     end
+
+    it "returns string representation with recursive attribute replaced with ... when an anonymous class" do
+      klass = Class.new(DataSpecs::Measure)
+      a = klass.allocate
+      a.send(:initialize, amount: 42, unit: a)
+
+      a.send(@method).should =~ /#<data amount=42, unit=#<data #<Class:0x.+?>:\.\.\.>>/
+    end
   end
 end

spec/tags/core/data/inspect_tags.txt

@@ -140,15 +140,20 @@ def with(**changes)
 
       def inspect
         klass = Primitive.class(self)
-        class_name = Primitive.module_anonymous?(klass) ? '' : "#{Primitive.module_name(klass)} "
-        members_and_values = to_h.map do |member, value|
-          if Truffle::CExt.rb_is_local_id(member) or Truffle::CExt.rb_is_const_id(member)
-            "#{member}=#{value.inspect}"
-          else
-            "#{member.inspect}=#{value.inspect}"
+
+        return "#<data #{klass}:...>" if Truffle::ThreadOperations.detect_recursion(self) do
+          class_name = Primitive.module_anonymous?(klass) ? nil : Primitive.module_name(klass)
+
+          members_and_values = to_h.map do |member, value|
+            if Truffle::CExt.rb_is_local_id(member) or Truffle::CExt.rb_is_const_id(member)
+              "#{member}=#{value.inspect}"
+            else
+              "#{member.inspect}=#{value.inspect}"
+            end
           end
+
+          return "#<data #{class_name}#{' ' if class_name}#{members_and_values.join(', ')}>"
         end
-        "#<data #{class_name}#{members_and_values.join(', ')}>"
       end
       alias_method :to_s, :inspect