From 0f553baffc7a0ff06f6cffffc943c0e8f7ee142f Mon Sep 17 00:00:00 2001
From: SUZUKI Sosuke <aosukeke@gmail.com>
Date: Fri, 30 May 2025 18:22:16 +0900
Subject: [PATCH] Don't print extra semicolon after `prettier-ignore`d
 index-signature (#17538)

* Don't print extra semicolon after `prettier-ignore`d index-signature

* Update snapshots

* Add changelog
---
 changelog_unreleased/typescript/17538.md      | 22 +++++++++++++++++++
 src/language-js/print/object.js               |  3 ++-
 .../__snapshots__/format.test.js.snap         | 20 +++++++++++++++++
 .../typescript/prettier-ignore/issue-16927.ts |  4 ++++
 4 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 changelog_unreleased/typescript/17538.md
 create mode 100644 tests/format/typescript/prettier-ignore/issue-16927.ts

diff --git a/changelog_unreleased/typescript/17538.md b/changelog_unreleased/typescript/17538.md
new file mode 100644
index 000000000..f0dd805dd
--- /dev/null
+++ b/changelog_unreleased/typescript/17538.md
@@ -0,0 +1,22 @@
+#### Don't print extra semicolon after `prettier-ignore`d index-signature (#17538 by @sosukesuzuki)
+
+<!-- prettier-ignore -->
+```tsx
+// Input
+type foo = {
+  // prettier-ignore
+  [key: string]: bar;
+};
+
+// Prettier stable
+type foo = {
+  // prettier-ignore
+  [key: string]: bar;;
+};
+
+// Prettier main
+type foo = {
+  // prettier-ignore
+  [key: string]: bar;
+};
+```
diff --git a/src/language-js/print/object.js b/src/language-js/print/object.js
index d1d788fb4..32fcd58a8 100644
--- a/src/language-js/print/object.js
+++ b/src/language-js/print/object.js
@@ -159,7 +159,8 @@ function printObject(path, options, print) {
         ((lastElem.type === "TSPropertySignature" ||
           lastElem.type === "TSCallSignatureDeclaration" ||
           lastElem.type === "TSMethodSignature" ||
-          lastElem.type === "TSConstructSignatureDeclaration") &&
+          lastElem.type === "TSConstructSignatureDeclaration" ||
+          lastElem.type === "TSIndexSignature") &&
           hasComment(lastElem, CommentCheckFlags.PrettierIgnore))))
   );
 
diff --git a/tests/format/typescript/prettier-ignore/__snapshots__/format.test.js.snap b/tests/format/typescript/prettier-ignore/__snapshots__/format.test.js.snap
index 574b60950..367e8cf4f 100644
--- a/tests/format/typescript/prettier-ignore/__snapshots__/format.test.js.snap
+++ b/tests/format/typescript/prettier-ignore/__snapshots__/format.test.js.snap
@@ -18,6 +18,26 @@ export const foo = // prettier-ignore
 ================================================================================
 `;
 
+exports[`issue-16927.ts format 1`] = `
+====================================options=====================================
+parsers: ["typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+type Foo = {
+    // prettier-ignore
+    [key: string]: bar;
+};
+
+=====================================output=====================================
+type Foo = {
+  // prettier-ignore
+  [key: string]: bar;
+};
+
+================================================================================
+`;
+
 exports[`mapped-types.ts format 1`] = `
 ====================================options=====================================
 parsers: ["typescript"]
diff --git a/tests/format/typescript/prettier-ignore/issue-16927.ts b/tests/format/typescript/prettier-ignore/issue-16927.ts
new file mode 100644
index 000000000..1ec77ded6
--- /dev/null
+++ b/tests/format/typescript/prettier-ignore/issue-16927.ts
@@ -0,0 +1,4 @@
+type Foo = {
+    // prettier-ignore
+    [key: string]: bar;
+};