From 4888a0d5df0e8c2f3c3febff3b5f09f994483b82 Mon Sep 17 00:00:00 2001
From: yeonjuan <yeonjuan93@naver.com>
Date: Fri, 23 Feb 2024 01:37:39 +0900
Subject: [PATCH 1/2] fix(eslint-plugin): [no-misused-promises] improve check
 union types

---
 .../eslint-plugin/src/rules/no-misused-promises.ts  |  4 ++++
 .../tests/rules/no-misused-promises.test.ts         | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/packages/eslint-plugin/src/rules/no-misused-promises.ts b/packages/eslint-plugin/src/rules/no-misused-promises.ts
index fa5f9ae5796b..c631b800a144 100644
--- a/packages/eslint-plugin/src/rules/no-misused-promises.ts
+++ b/packages/eslint-plugin/src/rules/no-misused-promises.ts
@@ -675,6 +675,10 @@ function isVoidReturningFunctionType(
 function returnsThenable(checker: ts.TypeChecker, node: ts.Node): boolean {
   const type = checker.getApparentType(checker.getTypeAtLocation(node));
 
+  if (type.isUnion()) {
+    return type.types.some(t => anySignatureIsThenableType(checker, node, t));
+  }
+
   if (anySignatureIsThenableType(checker, node, type)) {
     return true;
   }
diff --git a/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts b/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
index a6d6f1db5ad2..977639e37f6f 100644
--- a/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
+++ b/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
@@ -474,6 +474,11 @@ restTuple('Hello');
         };
       }
     `,
+    `
+declare function foo(cb: undefined | (() => void));
+declare const bar: undefined | (() => void);
+foo(bar);
+    `,
     // https://github.com/typescript-eslint/typescript-eslint/issues/6637
     {
       code: `
@@ -1227,5 +1232,13 @@ const test: ReturnsRecord = () => {
       `,
       errors: [{ line: 7, messageId: 'voidReturnProperty' }],
     },
+    {
+      code: `
+declare function foo(cb: undefined | (() => void));
+declare const bar: undefined | (() => Promise<void>);
+foo(bar);
+      `,
+      errors: [{ line: 4, messageId: 'voidReturnArgument' }],
+    },
   ],
 });

From a5c08f4ea49434eea98c7d37ec415658e0e7a8b4 Mon Sep 17 00:00:00 2001
From: yeonjuan <yeonjuan93@naver.com>
Date: Fri, 23 Feb 2024 20:58:09 +0900
Subject: [PATCH 2/2] apply reviews

---
 .../eslint-plugin/src/rules/no-misused-promises.ts  | 13 +++----------
 .../tests/rules/no-misused-promises.test.ts         |  8 ++++++++
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/packages/eslint-plugin/src/rules/no-misused-promises.ts b/packages/eslint-plugin/src/rules/no-misused-promises.ts
index c631b800a144..b7d556c893f0 100644
--- a/packages/eslint-plugin/src/rules/no-misused-promises.ts
+++ b/packages/eslint-plugin/src/rules/no-misused-promises.ts
@@ -674,14 +674,7 @@ function isVoidReturningFunctionType(
  */
 function returnsThenable(checker: ts.TypeChecker, node: ts.Node): boolean {
   const type = checker.getApparentType(checker.getTypeAtLocation(node));
-
-  if (type.isUnion()) {
-    return type.types.some(t => anySignatureIsThenableType(checker, node, t));
-  }
-
-  if (anySignatureIsThenableType(checker, node, type)) {
-    return true;
-  }
-
-  return false;
+  return tsutils
+    .unionTypeParts(type)
+    .some(t => anySignatureIsThenableType(checker, node, t));
 }
diff --git a/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts b/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
index 977639e37f6f..1910dd4f93f9 100644
--- a/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
+++ b/packages/eslint-plugin/tests/rules/no-misused-promises.test.ts
@@ -1236,6 +1236,14 @@ const test: ReturnsRecord = () => {
       code: `
 declare function foo(cb: undefined | (() => void));
 declare const bar: undefined | (() => Promise<void>);
+foo(bar);
+      `,
+      errors: [{ line: 4, messageId: 'voidReturnArgument' }],
+    },
+    {
+      code: `
+declare function foo(cb: string & (() => void));
+declare const bar: string & (() => Promise<void>);
 foo(bar);
       `,
       errors: [{ line: 4, messageId: 'voidReturnArgument' }],