From 7acedf8cedc18d5541f959c64da9b130dd5a4c9e Mon Sep 17 00:00:00 2001
From: TSUYUSATO Kitsune <make.just.on@gmail.com>
Date: Fri, 3 Nov 2017 08:54:47 +0900
Subject: [PATCH] Can't use `self` in toplevel method (#5227)

Related issue #5225
---
 spec/compiler/semantic/def_spec.cr            | 10 ++++++++++
 src/compiler/crystal/semantic/main_visitor.cr |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/spec/compiler/semantic/def_spec.cr b/spec/compiler/semantic/def_spec.cr
index 4cf7fede5280..3c35970ecc34 100644
--- a/spec/compiler/semantic/def_spec.cr
+++ b/spec/compiler/semantic/def_spec.cr
@@ -476,4 +476,14 @@ describe "Semantic: def" do
       foo(1)
       )) { int32.metaclass }
   end
+
+  it "can't use self in toplevel method" do
+    assert_error %(
+      def foo
+        self
+      end
+
+      foo
+    ), "there's no self in this scope"
+  end
 end
diff --git a/src/compiler/crystal/semantic/main_visitor.cr b/src/compiler/crystal/semantic/main_visitor.cr
index 75e09d5ff6f9..228a1d21ef17 100644
--- a/src/compiler/crystal/semantic/main_visitor.cr
+++ b/src/compiler/crystal/semantic/main_visitor.cr
@@ -341,6 +341,10 @@ module Crystal
     def visit(node : Var)
       var = @vars[node.name]?
       if var
+        if var.type?.is_a?(Program) && node.name == "self"
+          node.raise "there's no self in this scope"
+        end
+
         meta_var = @meta_vars[node.name]
         check_closured meta_var