Ensure pending_schema_names is always cleaned up

schemars/src/gen.rs

@@ -374,11 +374,29 @@ impl SchemaGenerator {
     }
 
     fn json_schema_internal<T: ?Sized + JsonSchema>(&mut self, name: &str) -> Schema {
-        self.pending_schema_names.insert(name.to_owned());
+        struct PendingSchemaState<'a> {
-        let schema = T::json_schema(self);
+            gen: &'a mut SchemaGenerator,
-        // FIXME schema name not removed if previous line panics
+            name: &'a str,
-        self.pending_schema_names.remove(name);
+            did_add: bool,
-        schema
+        }
+
+        impl<'a> PendingSchemaState<'a> {
+            fn new(gen: &'a mut SchemaGenerator, name: &'a str) -> Self {
+                let did_add = gen.pending_schema_names.insert(name.to_owned());
+                Self { gen, name, did_add }
+            }
+        }
+
+        impl Drop for PendingSchemaState<'_> {
+            fn drop(&mut self) {
+                if self.did_add {
+                    self.gen.pending_schema_names.remove(self.name);
+                }
+            }
+        }
+
+        let pss = PendingSchemaState::new(self, name);
+        T::json_schema(pss.gen)
     }
 }
 

schemars/tests/expected/inline-subschemas-recursive.json

@@ -23,29 +23,7 @@
       ],
       "properties": {
         "recursive": {
-          "type": "object",
+          "$ref": "#/definitions/RecursiveOuter"
-          "properties": {
-            "direct": {
-              "anyOf": [
-                {
-                  "$ref": "#/definitions/RecursiveOuter"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            },
-            "indirect": {
-              "anyOf": [
-                {
-                  "$ref": "#/definitions/RecursiveInner"
-                },
-                {
-                  "type": "null"
-                }
-              ]
-            }
-          }
         }
       }
     }
@@ -79,17 +57,6 @@
           }
         }
       }
-    },
-    "RecursiveInner": {
-      "type": "object",
-      "required": [
-        "recursive"
-      ],
-      "properties": {
-        "recursive": {
-          "$ref": "#/definitions/RecursiveOuter"
-        }
-      }
     }
   }
 }