From e0941f75b1bce002bf416403df85336b05412675 Mon Sep 17 00:00:00 2001
From: Aaron Moat <2937187+AaronMoat@users.noreply.github.com>
Date: Wed, 6 Sep 2023 08:29:04 +1000
Subject: [PATCH 1/2] OverlappingFieldsCanBeMergedRule: Fix performance
 degradation

---
 benchmark/repeated-fields-benchmark.js        | 15 ++++++
 .../rules/OverlappingFieldsCanBeMergedRule.ts | 50 +++++++++++++------
 2 files changed, 50 insertions(+), 15 deletions(-)
 create mode 100644 benchmark/repeated-fields-benchmark.js

diff --git a/benchmark/repeated-fields-benchmark.js b/benchmark/repeated-fields-benchmark.js
new file mode 100644
index 0000000000..7dd5b179b7
--- /dev/null
+++ b/benchmark/repeated-fields-benchmark.js
@@ -0,0 +1,15 @@
+'use strict';
+
+const { graphqlSync } = require('graphql/graphql.js');
+const { buildSchema } = require('graphql/utilities/buildASTSchema.js');
+
+const schema = buildSchema('type Query { hello: String! }');
+const source = `{ ${'hello '.repeat(250)}}`;
+
+module.exports = {
+  name: 'Many repeated fields',
+  count: 5,
+  measure() {
+    graphqlSync({ schema, source });
+  },
+};
diff --git a/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts b/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
index bdf6eb874e..35f2360946 100644
--- a/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
+++ b/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
@@ -5,10 +5,11 @@ import type { ObjMap } from '../../jsutils/ObjMap';
 import { GraphQLError } from '../../error/GraphQLError';
 
 import type {
+  DirectiveNode,
   FieldNode,
   FragmentDefinitionNode,
-  ObjectValueNode,
   SelectionSetNode,
+  ValueNode,
 } from '../../language/ast';
 import { Kind } from '../../language/kinds';
 import { print } from '../../language/printer';
@@ -588,7 +589,7 @@ function findConflict(
     }
 
     // Two field calls must have the same arguments.
-    if (stringifyArguments(node1) !== stringifyArguments(node2)) {
+    if (!sameArguments(node1, node2)) {
       return [
         [responseName, 'they have differing arguments'],
         [node1],
@@ -634,19 +635,38 @@ function findConflict(
   }
 }
 
-function stringifyArguments(fieldNode: FieldNode): string {
-  // FIXME https://github.com/graphql/graphql-js/issues/2203
-  const args = /* c8 ignore next */ fieldNode.arguments ?? [];
-
-  const inputObjectWithArgs: ObjectValueNode = {
-    kind: Kind.OBJECT,
-    fields: args.map((argNode) => ({
-      kind: Kind.OBJECT_FIELD,
-      name: argNode.name,
-      value: argNode.value,
-    })),
-  };
-  return print(sortValueNode(inputObjectWithArgs));
+function sameArguments(
+  node1: FieldNode | DirectiveNode,
+  node2: FieldNode | DirectiveNode,
+): boolean {
+  const args1 = node1.arguments;
+  const args2 = node2.arguments;
+
+  if (args1 === undefined || args1.length === 0) {
+    return args2 === undefined || args2.length === 0;
+  }
+  if (args2 === undefined || args2.length === 0) {
+    return false;
+  }
+
+  if (args1.length !== args2.length) {
+    return false;
+  }
+
+  const values2 = new Map(args2.map(({ name, value }) => [name.value, value]));
+  return args1.every((arg1) => {
+    const value1 = arg1.value;
+    const value2 = values2.get(arg1.name.value);
+    if (value2 === undefined) {
+      return false;
+    }
+
+    return stringifyValue(value1) === stringifyValue(value2);
+  });
+}
+
+function stringifyValue(value: ValueNode): string | null {
+  return print(sortValueNode(value));
 }
 
 // Two types conflict if both types could not apply to a value simultaneously.

From 3c127868af69b2fc43d06b89d769bf4be963c36b Mon Sep 17 00:00:00 2001
From: Aaron Moat <2937187+AaronMoat@users.noreply.github.com>
Date: Thu, 7 Sep 2023 10:19:54 +1000
Subject: [PATCH 2/2] Add coverage ignore comment

---
 src/validation/rules/OverlappingFieldsCanBeMergedRule.ts | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts b/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
index 35f2360946..4305064a6f 100644
--- a/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
+++ b/src/validation/rules/OverlappingFieldsCanBeMergedRule.ts
@@ -649,8 +649,11 @@ function sameArguments(
     return false;
   }
 
+  /* c8 ignore next */
   if (args1.length !== args2.length) {
+    /* c8 ignore next */
     return false;
+    /* c8 ignore next */
   }
 
   const values2 = new Map(args2.map(({ name, value }) => [name.value, value]));