allow immediate and frozen key/values in WeakMap

Author: Nicolas Laurent

CHANGELOG.md

@@ -69,6 +69,7 @@ Compatibility:
 * Implemented `Kernel#raise` `cause` parameter.
 * Improved compatibility of `Signal.trap` and `Kernel#trap` (#2287, @chrisseaton).
 * Implemented `GC.stat(:total_allocated_objects)` as `0` (#2292, @chrisseaton).
+* `ObjectSpace::WeakMap` now supports immediate and frozen values as both keys and values (#2267).
 
 Performance:
 

spec/tags/core/objectspace/weakmap/element_set_tags.txt

@@ -71,4 +71,20 @@
     map.each_value { |v| a << v }
     a.should == ["X"]
   end
+
+  it "supports constant objects" do
+    map = ObjectSpace::WeakMap.new
+    map[1] = 2
+    Primitive.gc_force
+    map[1].should == 2
+  end
+
+  it "supports frozen objects" do
+    map = ObjectSpace::WeakMap.new
+    x = "x".freeze
+    y = "y".freeze
+    map[x] = y
+    Primitive.gc_force
+    map[x].should == y
+  end
 end

spec/truffle/objectspace/weakmap_spec.rb

@@ -10,28 +10,15 @@
 
 module ObjectSpace
   # WeakMap uses identity comparison semantics. The implementation assumes that the Java representation of objects
-  # do compare (equals() and hashCode()) using object identity. This is the case for instances of RubyDynamicObject.
+  # do compare (equals() and hashCode()) using object identity. This is the case for instances of RubyDynamicObject,
+  # boxed primitives, and RubySymbol.
   #
   # However, results are unspecified if used with instances of TruffleObject that override equals() and
   # hashCode().
-  #
-  # Note that, following MRI, we disallow immediate (primitive) values and frozen objects as keys or value of
-  # WeakMap. We could easily transcend this limitation as we do not modify objects like MRI does (it sets a finalizer).
-  # However, keeping the limitation enables the above assumption of identity comparison.
   class WeakMap
     include Enumerable
 
-    private def check_key_or_value(kv, type)
-      if Primitive.immediate_value?(kv)
-        raise ArgumentError, "WeakMap #{type} can't be an instance of #{kv.class}"
-      elsif Truffle::KernelOperations.value_frozen?(kv)
-        raise FrozenError, "WeakMap #{type} can't be a frozen object"
-      end
-    end
-
     def []=(key, value)
-      check_key_or_value(key, 'key')
-      check_key_or_value(value, 'value')
       Primitive.weakmap_aset(self, key, value)
     end