Allow to use private default method from a trait

This commit fixes type checking of class that implement a trait which
contains a private method with a default implementation. Previously the
usage of such method resulted in an error during type checking saying
that the method is private.

This fixes #605.

Changelog: fixed

compiler/src/type_check/methods.rs

@@ -1220,7 +1220,8 @@ impl<'a> ImplementTraitMethods<'a> {
 
             let source = MethodSource::Implementation(trait_ins, method);
             let name = method.name(self.db()).clone();
-            let copy = method.copy_method(self.db_mut());
+            let module_id = class_id.module(self.db());
+            let copy = method.copy_method(self.db_mut(), module_id);
 
             // This is needed to ensure that the receiver of the default method
             // is typed as the class that implements the trait, not as the trait

std/test/diagnostics/class_with_trait_with_default_method.inko

@@ -0,0 +1,11 @@
+import foo.Foo
+
+class Bar {
+  fn baz {}
+}
+
+impl Foo for Bar {}
+
+fn example(value: Bar) {
+  value.foo
+}

std/test/diagnostics/class_with_trait_with_default_method/foo.inko

@@ -0,0 +1,5 @@
+trait pub Foo {
+  fn foo {
+    42
+  }
+}

types/src/lib.rs

@@ -2186,10 +2186,11 @@ impl MethodId {
         self.get(db).arguments.len()
     }
 
-    pub fn copy_method(self, db: &mut Database) -> MethodId {
-        let copy = self.get(db).clone();
+    pub fn copy_method(self, db: &mut Database, module: ModuleId) -> MethodId {
+        let mut copy = self.get(db).clone();
         let id = db.methods.len();
 
+        copy.module = module;
         db.methods.push(copy);
         MethodId(id)
     }