[GR-16394] Fix Array#to_h.

PullRequest: truffleruby/886

Author: chrisseaton

CHANGELOG.md

@@ -3,6 +3,7 @@
 Bug fixes:
 
 * Sharing for thread-safety of objects is now triggered later as intended, e.g., when a second `Thread` is started.
+* Fixed `Array#to_h` so it doesn't set a default value (#1698).
 
 Compatibility:
 

spec/ruby/core/array/to_h_spec.rb

@@ -35,6 +35,10 @@
     lambda { [].to_h(:a, :b) }.should raise_error(ArgumentError)
   end
 
+  it "produces a hash that returns nil for a missing element" do
+    [[:a, 1], [:b, 2]].to_h[:c].should be_nil
+  end
+
   ruby_version_is "2.6" do
     context "with block" do
       it "converts [key, value] pairs returned by the block to a Hash" do

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

@@ -1182,7 +1182,7 @@ def to_ary
   end
 
   def to_h
-    h = Hash.new(size)
+    h = Hash.new
     each_with_index do |elem, i|
       elem = yield(elem) if block_given?
       unless elem.respond_to?(:to_ary)