From 5ee4947bd6ea883df69f2dbf0c573d1b5ea54267 Mon Sep 17 00:00:00 2001
From: Lesley Dreyer <lesley@terascope.io>
Date: Mon, 29 Apr 2024 14:33:42 -0700
Subject: [PATCH] add changeset for previous PR 5973

---
 .changeset/weak-bears-move.md                      | 5 +++++
 packages/merge/src/typedefs-mergers/merge-nodes.ts | 7 +++++--
 2 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/weak-bears-move.md

diff --git a/.changeset/weak-bears-move.md b/.changeset/weak-bears-move.md
new file mode 100644
index 00000000000..70694411641
--- /dev/null
+++ b/.changeset/weak-bears-move.md
@@ -0,0 +1,5 @@
+---
+"@graphql-tools/merge": patch
+---
+
+Fix directive merging when directive name is inherited from object prototype (i.e. toString)
diff --git a/packages/merge/src/typedefs-mergers/merge-nodes.ts b/packages/merge/src/typedefs-mergers/merge-nodes.ts
index 56eab73b03f..36317469438 100644
--- a/packages/merge/src/typedefs-mergers/merge-nodes.ts
+++ b/packages/merge/src/typedefs-mergers/merge-nodes.ts
@@ -106,14 +106,17 @@ export function mergeGraphQLNodes(
             break;
           case Kind.DIRECTIVE_DEFINITION:
             if (mergedResultMap[name]) {
-              const isInheritedFromPrototype = name in {};
+              const isInheritedFromPrototype = name in {}; // i.e. toString
               if (isInheritedFromPrototype) {
                 if (!isNode(mergedResultMap[name])) {
                   mergedResultMap[name] = undefined as any;
                 }
               }
             }
-            mergedResultMap[name] = mergeDirective(nodeDefinition, mergedResultMap[name] as any);
+            mergedResultMap[name] = mergeDirective(
+              nodeDefinition,
+              mergedResultMap[name] as DirectiveDefinitionNode,
+            );
             break;
         }
       }