Patch for bug in OverlappingFieldsCanBeMergedRule in graphql@^15; apply with `patch-package` or `pnpm patch` or similar.

graphql@15.5.0.patch

diff --git a/validation/rules/OverlappingFieldsCanBeMergedRule.js b/validation/rules/OverlappingFieldsCanBeMergedRule.js
index 3fd18139ada7a3e766c78725c8a05ad18a42cddd..ec3cc13ce8efc700f39a4d0fc0f96331b7708906 100644
--- a/validation/rules/OverlappingFieldsCanBeMergedRule.js
+++ b/validation/rules/OverlappingFieldsCanBeMergedRule.js
@@ -180,6 +180,23 @@ function collectConflictsBetweenFieldsAndFragment(context, conflicts, cachedFiel
   // and any fragment names found in the given fragment.
 
   for (var i = 0; i < fragmentNames2.length; i++) {
+    // Memoize so two fragments are not compared for conflicts more than once.
+    const referencedFragmentName = fragmentNames2[i];
+    if (
+      comparedFragmentPairs.has(
+        referencedFragmentName,
+        fragmentName,
+        areMutuallyExclusive,
+      )
+    ) {
+      continue;
+    }
+    comparedFragmentPairs.add(
+      referencedFragmentName,
+      fragmentName,
+      areMutuallyExclusive,
+    );
+
     collectConflictsBetweenFieldsAndFragment(context, conflicts, cachedFieldsAndFragmentNames, comparedFragmentPairs, areMutuallyExclusive, fieldMap, fragmentNames2[i]);
   }
 } // Collect all conflicts found between two fragments, including via spreading in