From ca86e34f5557bd58b5ac81a2b716e52d7562b661 Mon Sep 17 00:00:00 2001
From: Rich Trott <rtrott@gmail.com>
Date: Sat, 2 Jan 2021 11:01:37 -0800
Subject: [PATCH] util: remove unreachable defensive coding

Now that we are using primordials in the first part of
isIdenticalTypedArrayType(), the defensive coding to get the correct
result (when Symbol.toStringTag is manipulated) is no longer reachable
or necessary. Remove the code.

Refs: https://coverage.nodejs.org/coverage-873d21cdc1266273/lib/internal/util/comparisons.js.html#L135

PR-URL: https://github.com/nodejs/node/pull/36744
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
---
 lib/internal/util/comparisons.js | 45 +++-----------------------------
 1 file changed, 3 insertions(+), 42 deletions(-)

diff --git a/lib/internal/util/comparisons.js b/lib/internal/util/comparisons.js
index 0bc46257e829fc..ed8ddf6ad321d8 100644
--- a/lib/internal/util/comparisons.js
+++ b/lib/internal/util/comparisons.js
@@ -44,15 +44,6 @@ const {
   isSymbolObject,
   isFloat32Array,
   isFloat64Array,
-  isUint8Array,
-  isUint8ClampedArray,
-  isUint16Array,
-  isUint32Array,
-  isInt8Array,
-  isInt16Array,
-  isInt32Array,
-  isBigInt64Array,
-  isBigUint64Array
 } = types;
 const {
   getOwnNonIndexProperties,
@@ -126,38 +117,6 @@ function isEqualBoxedPrimitive(val1, val2) {
   assert.fail(`Unknown boxed type ${val1}`);
 }
 
-function isIdenticalTypedArrayType(a, b) {
-  // Fast path to reduce type checks in the common case.
-  const check = types[`is${TypedArrayPrototypeGetSymbolToStringTag(a)}`];
-  if (check !== undefined && check(a)) {
-    return check(b);
-  }
-  // Manipulated Symbol.toStringTag.
-  for (const check of [
-    isUint16Array,
-    isUint32Array,
-    isInt8Array,
-    isInt16Array,
-    isInt32Array,
-    isFloat32Array,
-    isFloat64Array,
-    isBigInt64Array,
-    isBigUint64Array,
-    isUint8ClampedArray,
-    isUint8Array
-  ]) {
-    if (check(a)) {
-      return check(b);
-    }
-  }
-  /* c8 ignore next 4 */
-  assert.fail(
-    'Unknown TypedArray type checking ' +
-    `${TypedArrayPrototypeGetSymbolToStringTag(a)} ${a}\n` +
-    `and ${TypedArrayPrototypeGetSymbolToStringTag(b)} ${b}`
-  );
-}
-
 // Notes: Type tags are historical [[Class]] properties that can be set by
 // FunctionTemplate::SetClassName() in C++ or Symbol.toStringTag in JS
 // and retrieved using Object.prototype.toString.call(obj) in JS
@@ -241,8 +200,10 @@ function innerDeepEqual(val1, val2, strict, memos) {
       return false;
     }
   } else if (isArrayBufferView(val1)) {
-    if (!isIdenticalTypedArrayType(val1, val2))
+    if (TypedArrayPrototypeGetSymbolToStringTag(val1) !==
+        TypedArrayPrototypeGetSymbolToStringTag(val2)) {
       return false;
+    }
     if (!strict && (isFloat32Array(val1) || isFloat64Array(val1))) {
       if (!areSimilarFloatArrays(val1, val2)) {
         return false;