From 265a9fb9323a11067b4b826acc7624f2e62f1102 Mon Sep 17 00:00:00 2001
From: Yoshiya Hinosawa <stibium121@gmail.com>
Date: Mon, 12 Oct 2020 05:04:26 +0900
Subject: fix(console): fix inspection of Function (#7930)

This commit fixes the inspection of functions. The current
implementation gets the name of the type of the function
from "f.__proto__.constructor.name", and it throws when
the prototype is set to null.

This commit checks the prototype before accessing its
constructor name and uses the generic name 'Function'
if the prototype is not available.
---
 cli/rt/02_console.js           |  9 +++++++--
 cli/tests/unit/console_test.ts | 15 +++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

(limited to 'cli')

diff --git a/cli/rt/02_console.js b/cli/rt/02_console.js
index 363a95d90..0eb7f0aac 100644
--- a/cli/rt/02_console.js
+++ b/cli/rt/02_console.js
@@ -196,8 +196,13 @@
         return String(value[customInspect]());
       } catch {}
     }
-    // Might be Function/AsyncFunction/GeneratorFunction
-    const cstrName = Object.getPrototypeOf(value).constructor.name;
+    // Might be Function/AsyncFunction/GeneratorFunction/AsyncGeneratorFunction
+    let cstrName = Object.getPrototypeOf(value)?.constructor?.name;
+    if (!cstrName) {
+      // If prototype is removed or broken,
+      // use generic 'Function' instead.
+      cstrName = "Function";
+    }
     if (value.name && value.name !== "anonymous") {
       // from MDN spec
       return `[${cstrName}: ${value.name}]`;
diff --git a/cli/tests/unit/console_test.ts b/cli/tests/unit/console_test.ts
index df1420345..00a5927b1 100644
--- a/cli/tests/unit/console_test.ts
+++ b/cli/tests/unit/console_test.ts
@@ -347,6 +347,21 @@ unitTest(function consoleTestStringifyCircular(): void {
 });
 /* eslint-enable @typescript-eslint/explicit-function-return-type */
 
+unitTest(function consoleTestStringifyFunctionWithPrototypeRemoved(): void {
+  const f = function f() {};
+  Reflect.setPrototypeOf(f, null);
+  assertEquals(stringify(f), "[Function: f]");
+  const af = async function af() {};
+  Reflect.setPrototypeOf(af, null);
+  assertEquals(stringify(af), "[Function: af]");
+  const gf = function gf() {};
+  Reflect.setPrototypeOf(gf, null);
+  assertEquals(stringify(gf), "[Function: gf]");
+  const agf = function agf() {};
+  Reflect.setPrototypeOf(agf, null);
+  assertEquals(stringify(agf), "[Function: agf]");
+});
+
 unitTest(function consoleTestStringifyWithDepth(): void {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const nestedObj: any = { a: { b: { c: { d: { e: { f: 42 } } } } } };
-- 
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