From 1ebdcc6fb810e728bac291d1a3e43bd4a54ee5e8 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Tue, 1 Feb 2022 10:11:39 -0800
Subject: [PATCH] Fix inlay hint crash for jsdoc function type syntax (#47684)

* Fix inlay hint crash for jsdoc function type syntax

Parameters in JSDoc function types do not have names. The type does not
reflect this. This PR fixes the crash; I'll see how much churn it causes
to fix the type as well.

Fixes #47606

* make inlay hints test smaller
---
 src/compiler/checker.ts                   |  3 +++
 tests/cases/fourslash/inlayHintsCrash1.ts | 14 ++++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 tests/cases/fourslash/inlayHintsCrash1.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index cffd5acc456..82b2880ba14 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -31508,6 +31508,9 @@ namespace ts {
         }
 
         function getParameterIdentifierNameAtPosition(signature: Signature, pos: number): [parameterName: __String, isRestParameter: boolean] | undefined {
+            if (signature.declaration?.kind === SyntaxKind.JSDocFunctionType) {
+                return undefined;
+            }
             const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0);
             if (pos < paramCount) {
                 const param = signature.parameters[pos];
diff --git a/tests/cases/fourslash/inlayHintsCrash1.ts b/tests/cases/fourslash/inlayHintsCrash1.ts
new file mode 100644
index 00000000000..793bac5eff2
--- /dev/null
+++ b/tests/cases/fourslash/inlayHintsCrash1.ts
@@ -0,0 +1,14 @@
+/// <reference path="fourslash.ts" />
+// @allowJs: true
+// @checkJs: true
+// @Filename: foo.js
+//// /**
+////  * @param {function(string): boolean} f
+////  */
+//// function doThing(f) {
+////     f(100)
+//// }
+verify.getInlayHints([], undefined, {
+    includeInlayVariableTypeHints: true,
+    includeInlayParameterNameHints: "all",
+});