From 0c09d2f1726e188d7fe95c84b2512f3ce015e96f Mon Sep 17 00:00:00 2001
From: "Lyu, Wei-Da" <36730922+jasonlyu123@users.noreply.github.com>
Date: Tue, 6 Dec 2022 04:23:59 +0800
Subject: [PATCH] quick fix for a nullable missing callback function (#51743)

---
 src/services/codefixes/fixAddMissingMember.ts |  2 +-
 .../codeFixAddMissingFunctionDeclaration26.ts | 29 +++++++++++++++++++
 .../codeFixAddMissingFunctionDeclaration27.ts | 29 +++++++++++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 tests/cases/fourslash/codeFixAddMissingFunctionDeclaration26.ts
 create mode 100644 tests/cases/fourslash/codeFixAddMissingFunctionDeclaration27.ts

diff --git a/src/services/codefixes/fixAddMissingMember.ts b/src/services/codefixes/fixAddMissingMember.ts
index 490d65171be..80fdb0380ad 100644
--- a/src/services/codefixes/fixAddMissingMember.ts
+++ b/src/services/codefixes/fixAddMissingMember.ts
@@ -330,7 +330,7 @@ function getInfo(sourceFile: SourceFile, tokenPos: number, errorCode: number, ch
     }
 
     if (isIdentifier(token)) {
-        const type = checker.getContextualType(token);
+        const type = checker.getContextualType(token)?.getNonNullableType();
         if (type && getObjectFlags(type) & ObjectFlags.Anonymous) {
             const signature = firstOrUndefined(checker.getSignaturesOfType(type, SignatureKind.Call));
             if (signature === undefined) return undefined;
diff --git a/tests/cases/fourslash/codeFixAddMissingFunctionDeclaration26.ts b/tests/cases/fourslash/codeFixAddMissingFunctionDeclaration26.ts
new file mode 100644
index 00000000000..156be5141e8
--- /dev/null
+++ b/tests/cases/fourslash/codeFixAddMissingFunctionDeclaration26.ts
@@ -0,0 +1,29 @@
+/// <reference path="fourslash.ts" />
+
+// @strict: true
+
+////interface Foo {
+////    a: ((e: any) => void) | null;
+////}
+////
+////const foo: Foo = {
+////    a: fn
+////}
+
+verify.codeFix({
+    index: 0,
+    description: [ts.Diagnostics.Add_missing_function_declaration_0.message, "fn"],
+    newFileContent:
+`interface Foo {
+    a: ((e: any) => void) | null;
+}
+
+const foo: Foo = {
+    a: fn
+}
+
+function fn(e: any): void {
+    throw new Error("Function not implemented.");
+}
+`
+});
diff --git a/tests/cases/fourslash/codeFixAddMissingFunctionDeclaration27.ts b/tests/cases/fourslash/codeFixAddMissingFunctionDeclaration27.ts
new file mode 100644
index 00000000000..363dac2a30d
--- /dev/null
+++ b/tests/cases/fourslash/codeFixAddMissingFunctionDeclaration27.ts
@@ -0,0 +1,29 @@
+/// <reference path="fourslash.ts" />
+
+// @strict: true
+
+////interface Foo {
+////    a?: ((e: any) => void);
+////}
+////
+////const foo: Foo = {
+////    a: fn
+////}
+
+verify.codeFix({
+    index: 0,
+    description: [ts.Diagnostics.Add_missing_function_declaration_0.message, "fn"],
+    newFileContent:
+`interface Foo {
+    a?: ((e: any) => void);
+}
+
+const foo: Foo = {
+    a: fn
+}
+
+function fn(e: any): void {
+    throw new Error("Function not implemented.");
+}
+`
+});