Fix Array#sort_by! and raise FrozenError lazily only during iteration when method called without a block

Author: andrykonchin

spec/ruby/core/array/reject_spec.rb

@@ -116,6 +116,11 @@
     -> { ArraySpecs.empty_frozen_array.reject! {} }.should raise_error(FrozenError)
   end
 
+  it "raises a FrozenError on a frozen array only during iteration if called without a block" do
+    enum = ArraySpecs.frozen_array.reject!
+    -> { enum.each {} }.should raise_error(FrozenError)
+  end
+
   it "does not truncate the array is the block raises an exception" do
     a = [1, 2, 3]
     begin

spec/ruby/core/array/shared/keep_if.rb

@@ -57,6 +57,11 @@
         -> { @frozen.send(@method) { false } }.should raise_error(FrozenError)
       end
     end
+
+    it "raises a FrozenError on a frozen array only during iteration if called without a block" do
+      enum = @frozen.send(@method)
+      -> { enum.each {} }.should raise_error(FrozenError)
+    end
   end
 
   it "does not truncate the array is the block raises an exception" do

spec/ruby/core/array/sort_by_spec.rb

@@ -32,6 +32,11 @@
     -> { ArraySpecs.empty_frozen_array.sort_by! {}}.should raise_error(FrozenError)
   end
 
+  it "raises a FrozenError on a frozen array only during iteration if called without a block" do
+    enum = ArraySpecs.frozen_array.sort_by!
+    -> { enum.each {} }.should raise_error(FrozenError)
+  end
+
   it "returns the specified value when it would break in the given block" do
     [1, 2, 3].sort_by!{ break :a }.should == :a
   end

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

@@ -1259,10 +1259,10 @@ def drop(n)
   end
 
   def sort_by!(&block)
-    Primitive.check_frozen self
-
     return to_enum(:sort_by!) { size } unless block_given?
 
+    Primitive.check_frozen self
+
     Primitive.steal_array_storage(self, sort_by(&block))
   end