From 8d7a8c91a618805a80707496d62ab8e62bd850d9 Mon Sep 17 00:00:00 2001
From: Ary Borenszweig <asterite@gmail.com>
Date: Thu, 28 Jan 2021 14:45:38 -0300
Subject: [PATCH] Compiler: use path lookup when looking up type for autocast
 match (#10318)

---
 spec/compiler/semantic/automatic_cast_spec.cr | 20 +++++++++++++++++++
 src/compiler/crystal/semantic/main_visitor.cr |  2 +-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/spec/compiler/semantic/automatic_cast_spec.cr b/spec/compiler/semantic/automatic_cast_spec.cr
index bdb0a02f3d8e..c39b0e4bff8b 100644
--- a/spec/compiler/semantic/automatic_cast_spec.cr
+++ b/spec/compiler/semantic/automatic_cast_spec.cr
@@ -596,4 +596,24 @@ describe "Semantic: automatic cast" do
       ),
       "ambiguous call, implicit cast of 255 matches all of UInt64, Int64"
   end
+
+  it "autocasts nested type from non-nested type (#10315)" do
+    assert_no_errors(%(
+      module Moo
+        enum Color
+          Red
+        end
+
+        abstract class Foo
+          def initialize(color : Color = :red)
+          end
+        end
+      end
+
+      class Bar < Moo::Foo
+      end
+
+      Bar.new
+      ))
+  end
 end
diff --git a/src/compiler/crystal/semantic/main_visitor.cr b/src/compiler/crystal/semantic/main_visitor.cr
index 7f57bd8f8054..e9dbd442d15f 100644
--- a/src/compiler/crystal/semantic/main_visitor.cr
+++ b/src/compiler/crystal/semantic/main_visitor.cr
@@ -769,7 +769,7 @@ module Crystal
           # OK
         else
           # Check autocast too
-          restriction_type = scope.lookup_type(restriction, free_vars: free_vars)
+          restriction_type = (path_lookup || scope).lookup_type(restriction, free_vars: free_vars)
           if casted_value = check_automatic_cast(value, restriction_type, node)
             value = casted_value
           else