From 8a883d8a1c8899f94a3e2ae09cb2069bde2b2150 Mon Sep 17 00:00:00 2001
From: Ian MacLeod <ian@nevir.net>
Date: Fri, 10 Feb 2023 08:14:49 -0800
Subject: [PATCH] Fix link/core/types when TypeScript
 exactOptionalPropertyTypes mode is enabled (#10497)

---------

Co-authored-by: alessia <alessia@apollographql.com>
---
 .changeset/tricky-berries-perform.md | 5 +++++
 src/link/core/types.ts               | 8 +++-----
 2 files changed, 8 insertions(+), 5 deletions(-)
 create mode 100644 .changeset/tricky-berries-perform.md

diff --git a/.changeset/tricky-berries-perform.md b/.changeset/tricky-berries-perform.md
new file mode 100644
index 00000000000..b12df6fd26a
--- /dev/null
+++ b/.changeset/tricky-berries-perform.md
@@ -0,0 +1,5 @@
+---
+"@apollo/client": patch
+---
+
+Update `SingleExecutionResult` and `IncrementalPayload`'s `data` types such that they no longer include `undefined`, which was not a valid runtime value, to fix errors when TypeScript's `exactOptionalPropertyTypes` is enabled.
diff --git a/src/link/core/types.ts b/src/link/core/types.ts
index 230f51dea6b..0add4d9d666 100644
--- a/src/link/core/types.ts
+++ b/src/link/core/types.ts
@@ -5,8 +5,6 @@ export { DocumentNode };
 import { Observable } from "../../utilities";
 
 export type Path = ReadonlyArray<string | number>;
-type Data<T> = T | null | undefined;
-
 
 interface ExecutionPatchResultBase {
   hasNext?: boolean;
@@ -17,7 +15,7 @@ export interface ExecutionPatchInitialResult<
   TExtensions = Record<string, any>
 > extends ExecutionPatchResultBase {
   // if data is present, incremental is not
-  data: Data<TData>;
+  data: TData | null | undefined;
   incremental?: never;
   errors?: ReadonlyArray<GraphQLError>;
   extensions?: TExtensions;
@@ -29,7 +27,7 @@ export interface IncrementalPayload<
 > {
   // data and path must both be present
   // https://github.com/graphql/graphql-spec/pull/742/files#diff-98d0cd153b72b63c417ad4238e8cc0d3385691ccbde7f7674bc0d2a718b896ecR288-R293
-  data: Data<TData>;
+  data: TData | null;
   label?: string;
   path: Path;
   errors?: ReadonlyArray<GraphQLError>;
@@ -79,7 +77,7 @@ export interface SingleExecutionResult<
   TContext = DefaultContext,
   TExtensions = Record<string, any>
 > extends ExecutionResult<TData, TExtensions> {
-  data?: Data<TData>;
+  data?: TData | null;
   context?: TContext;
 }