Handle RBS type aliases within an empty Class or Module definition

Co-authored-by: Alexandre Terrasa <[email protected]>
Co-authored-by: Emily Samp <[email protected]>
Co-authored-by: Sid Challa <[email protected]>

Author: 4 people

rbs/CommentsAssociator.cc

@@ -279,6 +279,25 @@ void CommentsAssociator::processTrailingComments(parser::Node *node, parser::Nod
 }
 
 unique_ptr<parser::Node> CommentsAssociator::walkBody(parser::Node *node, unique_ptr<parser::Node> body) {
+    bool allowTypeAlias = false;
+    if (!contextAllowingTypeAlias.empty()) {
+        allowTypeAlias = contextAllowingTypeAlias.back().first;
+    }
+
+    if (allowTypeAlias && body == nullptr) {
+        int endLine = core::Loc::pos2Detail(ctx.file.data(ctx), node->loc.endPos()).line;
+        auto nodes = parser::NodeVec();
+
+        maybeInsertStandalonePlaceholders(nodes, 0, lastLine, endLine);
+        lastLine = endLine;
+
+        if (!nodes.empty()) {
+            return make_unique<parser::Begin>(node->loc, move(nodes));
+        }
+
+        return nullptr;
+    }
+
     if (body == nullptr) {
         auto nodes = parser::NodeVec();
         processTrailingComments(node, nodes);

test/testdata/rbs/signatures_type_aliases.rb

@@ -161,3 +161,19 @@ module TrailingTypeAlias
 module EmptyTypeAlias
   #: type a = Integer
 end
+
+#: -> EmptyTypeAlias::a
+def empty_module_type_alias
+  "42"
+# ^^^^ error: Expected `Integer` but found `String("42")` for method result type
+end
+
+class EmptyClass
+  #: type b = String
+end
+
+#: -> EmptyClass::b
+def empty_class_alias_type
+  42
+# ^^ error: Expected `String` but found `Integer(42)` for method result type
+end

test/testdata/rbs/signatures_type_aliases.rb.rewrite-tree.exp

@@ -1,4 +1,20 @@
 class <emptyTree><<C <root>>> < (::<todo sym>)
+  ::T::Sig::WithoutRuntime.sig() do ||
+    <self>.returns(<emptyTree>::<C EmptyTypeAlias>::<C type a>)
+  end
+
+  def empty_module_type_alias<<todo method>>(&<blk>)
+    "42"
+  end
+
+  ::T::Sig::WithoutRuntime.sig() do ||
+    <self>.returns(<emptyTree>::<C EmptyClass>::<C type b>)
+  end
+
+  def empty_class_alias_type<<todo method>>(&<blk>)
+    42
+  end
+
   module <emptyTree>::<C Errors><<C <todo sym>>> < ()
     ::T::Sig::WithoutRuntime.sig() do ||
       <self>.void()
@@ -252,4 +268,14 @@ class <emptyTree><<C <root>>> < (::<todo sym>)
       <emptyTree>::<C Integer>
     end
   end
+
+  <runtime method definition of empty_module_type_alias>
+
+  class <emptyTree>::<C EmptyClass><<C <todo sym>>> < (::<todo sym>)
+    <emptyTree>::<C type b> = ::<root>::<C T>.type_alias() do ||
+      <emptyTree>::<C String>
+    end
+  end
+
+  <runtime method definition of empty_class_alias_type>
 end