Compiler: check if C function needs to be converted to a Crystal proc…

… when accesing it through an instance var. Fixes #2515
crystal-lang · Apr 25, 2016 · da078e2 · da078e2
1 parent c1affec
commit da078e2
Showing 2 changed files with 21 additions and 0 deletions.
diff --git a/spec/compiler/codegen/lib_spec.cr b/spec/compiler/codegen/lib_spec.cr
@@ -192,4 +192,18 @@ describe "Code gen: lib" do
       LibFoo.foo(nil)
       ))
   end
+
+  it "casts C fun to Crystal proc when accessing instance var (#2515)" do
+    codegen(%(
+      require "prelude"
+
+      lib LibFoo
+        struct Some
+          x : ->
+        end
+      end
+
+      LibFoo::Some.new.to_s
+      ))
+  end
 end
diff --git a/src/compiler/crystal/codegen/codegen.cr b/src/compiler/crystal/codegen/codegen.cr
@@ -1000,6 +1000,13 @@ module Crystal
       ivar = type.lookup_instance_var_with_owner(name).instance_var
       ivar_ptr = instance_var_ptr type, name, value
       @last = downcast ivar_ptr, node_type, ivar.type, false
+      if type.is_a?(CStructOrUnionType)
+        # When reading the instance variable of a C struct or union
+        # we need to convert C functions to Crystal procs. This
+        # can happen for example in Struct#to_s, where all fields
+        # are inspected.
+        @last = check_c_fun node_type, @last
+      end
       false
     end