More fixes for deriving JsonSchema inside macro

schemars/tests/expected/macro_built_enum.json

@@ -0,0 +1,23 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "OuterEnum",
+  "anyOf": [
+    {
+      "type": "object",
+      "required": [
+        "InnerStruct"
+      ],
+      "properties": {
+        "InnerStruct": {
+          "$ref": "#/definitions/InnerStruct"
+        }
+      },
+      "additionalProperties": false
+    }
+  ],
+  "definitions": {
+    "InnerStruct": {
+      "type": "object"
+    }
+  }
+}

schemars/tests/macro.rs

@@ -20,3 +20,48 @@ build_struct!(A { v: i32 });
 fn macro_built_struct() -> TestResult {
     test_default_generated_schema::<A>("macro_built_struct")
 }
+
+macro_rules! build_enum {
+    (
+        $(#[$outer_derive:meta])*
+        $outer:ident {
+            $($(#[$inner_derive:meta])*
+            $inner:ident {
+                $( $(#[$field_attribute:meta])*
+                   $field:ident : $ty:ty),*
+            })*
+        }
+    ) => {
+
+        $(
+            $(#[$inner_derive])*
+            pub struct $inner {
+                $(
+                    $(#[$field_attribute])*
+                    pub $field: $ty
+                ),*
+            }
+        )*
+
+        $(#[$outer_derive])*
+        pub enum $outer {
+            $(
+                $inner($inner)
+            ),*
+        }
+    }
+}
+
+build_enum!(
+    #[derive(Debug, JsonSchema)]
+    OuterEnum {
+        #[derive(Debug, JsonSchema)]
+        InnerStruct {}
+    }
+
+);
+
+#[test]
+fn macro_built_enum() -> TestResult {
+    test_default_generated_schema::<OuterEnum>("macro_built_enum")
+}