Fix deriving JsonSchema inside macro (#79)

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## [0.8.3] - **In-dev**
+### Fixed:
+- Fix deriving JsonSchema on types defined inside macros (https://github.com/GREsau/schemars/issues/66 / https://github.com/GREsau/schemars/pull/79)
+
 ## [0.8.2] - 2021-03-27
 ### Added:
 - Enable generating a schema from any serializable value using `schema_for_value!(...)` macro or `SchemaGenerator::root_schema_for_value()`/`SchemaGenerator::into_root_schema_for_value()` methods (https://github.com/GREsau/schemars/pull/75)

schemars/tests/expected/macro_built_struct.json

@@ -0,0 +1,20 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "A",
+  "type": "object",
+  "required": [
+    "v",
+    "x"
+  ],
+  "properties": {
+    "x": {
+      "type": "integer",
+      "format": "uint8",
+      "minimum": 0.0
+    },
+    "v": {
+      "type": "integer",
+      "format": "int32"
+    }
+  }
+}

schemars/tests/macro.rs

@@ -0,0 +1,22 @@
+mod util;
+use schemars::JsonSchema;
+use util::*;
+
+macro_rules! build_struct {
+    (
+        $id:ident { $($t:tt)* }
+    ) => {
+        #[derive(Debug, JsonSchema)]
+        pub struct $id {
+            x: u8,
+            $($t)*
+        }
+    };
+}
+
+build_struct!(A { v: i32 });
+
+#[test]
+fn macro_built_struct() -> TestResult {
+    test_default_generated_schema::<A>("macro_built_struct")
+}

schemars_derive/src/schema_exprs.rs

@@ -390,7 +390,9 @@ fn expr_for_struct(
 
     let mut type_defs = Vec::new();
 
-    let properties: Vec<_> = property_fields.into_iter().map(|field| {
+    let properties: Vec<_> = property_fields
+        .into_iter()
+        .map(|field| {
             let name = field.name();
             let default = field_default_expr(field, set_container_default.is_some());
 
@@ -411,11 +413,13 @@ fn expr_for_struct(
                 type_defs.push(type_def);
             }
 
-        quote_spanned! {ty.span()=>
-            <#ty as schemars::JsonSchema>::add_schema_as_property(gen, &mut schema_object, #name.to_owned(), #metadata, #required);
-        }
+            let args = quote!(gen, &mut schema_object, #name.to_owned(), #metadata, #required);
 
-    }).collect();
+            quote_spanned! {ty.span()=>
+                <#ty as schemars::JsonSchema>::add_schema_as_property(#args);
+            }
+        })
+        .collect();
 
     let flattens: Vec<_> = flattened_fields
         .into_iter()