Merge branch 'fix-2875' (close PR #2876)

Author: jgonggrijp

modules/_toDataView.js

@@ -0,0 +1,11 @@
+import getByteLength from './_getByteLength.js';
+
+// Internal function to wrap or shallow-copy an ArrayBuffer,
+// typed array or DataView to a new DataView, reusing the buffer.
+export default function toDataView(bufferSource) {
+  return new DataView(
+    bufferSource.buffer || bufferSource,
+    bufferSource.byteOffset,
+    getByteLength(bufferSource)
+  );
+}

modules/isEqual.js

@@ -5,6 +5,7 @@ import isTypedArray from './isTypedArray.js';
 import isFunction from './isFunction.js';
 import keys from './keys.js';
 import has from './_has.js';
+import toDataView from './_toDataView.js';
 
 // Internal recursive comparison function for `_.isEqual`.
 function eq(a, b, aStack, bStack) {
@@ -53,12 +54,11 @@ function deepEq(a, b, aStack, bStack) {
       return SymbolProto.valueOf.call(a) === SymbolProto.valueOf.call(b);
     case '[object ArrayBuffer]':
       // Coerce to `DataView` so we can fall through to the next case.
-      return deepEq(new DataView(a), new DataView(b), aStack, bStack);
+      return deepEq(toDataView(a), toDataView(b), aStack, bStack);
     case '[object DataView]':
       var byteLength = getByteLength(a);
-      if (byteLength !== getByteLength(b)) {
-        return false;
-      }
+      if (byteLength !== getByteLength(b)) return false;
+      if (a.buffer === b.buffer && a.byteOffset === b.byteOffset) return true;
       while (byteLength--) {
         if (a.getUint8(byteLength) !== b.getUint8(byteLength)) {
           return false;
@@ -69,7 +69,7 @@ function deepEq(a, b, aStack, bStack) {
 
   if (isTypedArray(a)) {
     // Coerce typed arrays to `DataView`.
-    return deepEq(new DataView(a.buffer), new DataView(b.buffer), aStack, bStack);
+    return deepEq(toDataView(a), toDataView(b), aStack, bStack);
   }
 
   var areArrays = className === '[object Array]';

test/objects.js

@@ -583,8 +583,6 @@
       assert.strictEqual(_.isEqual(symbol, sameStringSymbol), false, 'Different symbols of same string are not equal');
     }
 
-
-
     // typed arrays
     if (typeof ArrayBuffer !== 'undefined') {
       var u8 = new Uint8Array([1, 2]);
@@ -608,10 +606,13 @@
       assert.notOk(_.isEqual(new DataView(u8.buffer), new DataView(u16one.buffer)), 'Different DataViews with different byte data are not equal');
       assert.notOk(_.isEqual(u8.buffer, u16.buffer), 'Different ArrayBuffers with different length are not equal');
       assert.notOk(_.isEqual(u8.buffer, u16one.buffer), 'Different ArrayBuffers with different byte data are not equal');
-    }
 
-    //assert.ok(_.isEqual(new DataView(u8.buffer)), new DataView(u8b.buffer))
-    //assert.notOk(_.isEqual(new DataView((new Uint8Array([1,2])).buffer), new DataView((new Uint8Array([5,6,10])).buffer));
+      // Regression tests for #2875.
+      var shared = new Uint8Array([1, 2, 3, 4]);
+      var view1 = new Uint8Array(shared.buffer, 0, 2);
+      var view2 = new Uint8Array(shared.buffer, 2, 2);
+      assert.notOk(_.isEqual(view1, view2), 'same buffer with different offset is not equal');
+    }
   });
 
   QUnit.test('isEmpty', function(assert) {