From 48c9bc4aea6061db7dfd7983c6f7ac3512176b36 Mon Sep 17 00:00:00 2001
From: Kirk Waiblinger <53019676+kirkwaiblinger@users.noreply.github.com>
Date: Thu, 4 Apr 2024 01:39:31 -0600
Subject: [PATCH] Yield expression parens (#16194)

Co-authored-by: fisker Cheung <lionkay@gmail.com>
---
 changelog_unreleased/typescript/16194.md      | 21 +++++++++++++++++++
 src/language-js/needs-parens.js               |  5 ++++-
 .../cast/__snapshots__/jsfmt.spec.js.snap     |  8 +++++++
 tests/format/typescript/cast/parenthesis.ts   |  4 ++++
 4 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 changelog_unreleased/typescript/16194.md

diff --git a/changelog_unreleased/typescript/16194.md b/changelog_unreleased/typescript/16194.md
new file mode 100644
index 000000000..f1dafbc17
--- /dev/null
+++ b/changelog_unreleased/typescript/16194.md
@@ -0,0 +1,21 @@
+#### Add necessary parentheses to yield expressions (#16194 by @kirkwaiblinger)
+
+Add parentheses around yield expressions if parent is an angle-bracket type assertion.
+
+<!-- prettier-ignore -->
+```ts
+// Input
+function* g() {
+  const y = <T>(yield x);
+}
+
+// Prettier stable
+function* g() {
+  const y = <T>yield x;
+}
+
+// Prettier main
+function* g() {
+  const y = <T>(yield x);
+}
+```
diff --git a/src/language-js/needs-parens.js b/src/language-js/needs-parens.js
index ba3a49efd..c0074632b 100644
--- a/src/language-js/needs-parens.js
+++ b/src/language-js/needs-parens.js
@@ -472,7 +472,10 @@ function needsParens(path, options) {
       }
 
     case "YieldExpression":
-      if (parent.type === "AwaitExpression") {
+      if (
+        parent.type === "AwaitExpression" ||
+        parent.type === "TSTypeAssertion"
+      ) {
         return true;
       }
     // else fallthrough
diff --git a/tests/format/typescript/cast/__snapshots__/jsfmt.spec.js.snap b/tests/format/typescript/cast/__snapshots__/jsfmt.spec.js.snap
index 19b789bd9..b46abb429 100644
--- a/tests/format/typescript/cast/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/format/typescript/cast/__snapshots__/jsfmt.spec.js.snap
@@ -355,6 +355,10 @@ true || <x>a;
 <x>a + <x>b;
 (<x>a) = 1;
 
+function * g() {
+  const a = <T>(yield b);
+}
+
 =====================================output=====================================
 <DocumentHighlightKind>(a ? b : c);
 <any>(() => {});
@@ -365,6 +369,10 @@ true || <x>a;
 <x>a + <x>b;
 (<x>a) = 1;
 
+function* g() {
+  const a = <T>(yield b);
+}
+
 ================================================================================
 `;
 
diff --git a/tests/format/typescript/cast/parenthesis.ts b/tests/format/typescript/cast/parenthesis.ts
index edada7854..db00a98be 100644
--- a/tests/format/typescript/cast/parenthesis.ts
+++ b/tests/format/typescript/cast/parenthesis.ts
@@ -6,3 +6,7 @@
 true || <x>a;
 <x>a + <x>b;
 (<x>a) = 1;
+
+function * g() {
+  const a = <T>(yield b);
+}