Fixed: can't dup class inheriting abstract class

crystal-lang · Dec 18, 2016 · 02f5555 · 02f5555
1 parent b8334ae
commit 02f5555
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Showing 2 changed files with 23 additions and 1 deletion.
diff --git a/spec/std/reference_spec.cr b/spec/std/reference_spec.cr
@@ -25,6 +25,16 @@ module ReferenceSpec
 
     def_clone
   end
+
+  abstract class Abstract
+  end
+
+  class Concrete < Abstract
+    property x
+
+    def initialize(@x : Int32)
+    end
+  end
 end
 
 describe "Reference" do
@@ -79,6 +89,14 @@ describe "Reference" do
     duplicate.y.should be(original.y)
   end
 
+  it "can dup class that inherits abstract class" do
+    original = ReferenceSpec::Concrete.new(2).as(ReferenceSpec::Abstract)
+    duplicate = original.dup
+    duplicate.should be_a(ReferenceSpec::Concrete)
+    duplicate.should_not be(original)
+    duplicate.x.should eq(original.x)
+  end
+
   it "clones with def_clone" do
     original = ReferenceSpec::DupCloneClass.new
     clone = original.clone

diff --git a/src/reference.cr b/src/reference.cr
@@ -37,7 +37,11 @@ class Reference
   # This allocates a new object and copies the contents of
   # `self` into it.
   def dup
-    {% begin %}
+    {% if @type.abstract? %}
+      # This shouldn't happen, as the type is abstract,
+      # but we need to avoid the allocate invocation below
+      raise "can't dup {{@type}}"
+    {% else %}
       dup = {{@type}}.allocate
       dup.as(Void*).copy_from(self.as(Void*), instance_sizeof({{@type}}))
       dup