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			89 lines
		
	
	
		
			2.8 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			89 lines
		
	
	
		
			2.8 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
| // Copyright 2017 the V8 project authors. All rights reserved.
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| // Use of this source code is governed by a BSD-style license that can be
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| // found in the LICENSE file.
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| 
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| // The bug was that destructuring assignments which occur inside a lazy arrow
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| // function parameter list were not rewritten.
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| 
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| // Repro from the bug (slightly modified so that it doesn't produce a run-time
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| // exception).
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| (({x = {} = {}}) => {})({});
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| 
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| // ... and without the parens.
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| let a0 = ({x = {} = {}}) => {};
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| a0({});
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| 
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| // Testing that the destructuring assignments also work properly. The semantics
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| // are: The value of the destructuring assignment is an object {myprop: 2115}
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| // and 2115 also gets assigned to global_side_assignment. So the default value
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| // for x is {myprop: 2115}. This is the value which x will have if the function
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| // is called with an object which doesn't have property x.
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| let called = false;
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| let global_side_assignment = undefined;
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| (({x = {myprop: global_side_assignment} = {myprop: 2115}}) => {
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|   assertTrue('myprop' in x);
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|   assertEquals(2115, x.myprop);
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|   called = true;
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| })({});
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| assertTrue(called);
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| assertEquals(2115, global_side_assignment);
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| 
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| // If the parameter is an object which has property x, the default value is not
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| // used.
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| called = false;
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| global_side_assignment = undefined;
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| (({x = {myprop: global_side_assignment} = {myprop: 2115}}) => {
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|   assertEquals(3000, x);
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|   called = true;
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| })({x: 3000});
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| assertTrue(called);
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| // Global side assignment doesn't happen, since the default value was not used.
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| assertEquals(undefined, global_side_assignment);
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| 
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| // Different kinds of lazy arrow functions (it's actually a bit weird that the
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| // above functions are lazy, since they are parenthesized).
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| called = false;
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| global_side_assignment = undefined;
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| let a1 = ({x = {myprop: global_side_assignment} = {myprop: 2115}}) => {
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|   assertTrue('myprop' in x);
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|   assertEquals(2115, x.myprop);
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|   called = true;
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| }
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| a1({});
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| assertTrue(called);
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| assertEquals(2115, global_side_assignment);
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| 
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| called = false;
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| global_side_assignment = undefined;
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| let a2 = ({x = {myprop: global_side_assignment} = {myprop: 2115}}) => {
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|   assertEquals(3000, x);
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|   called = true;
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| }
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| a2({x: 3000});
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| assertTrue(called);
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| assertEquals(undefined, global_side_assignment);
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| 
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| // We never had a problem with non-arrow functions, but testing them too for
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| // completeness.
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| called = false;
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| global_side_assignment = undefined;
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| function f1({x = {myprop: global_side_assignment} = {myprop: 2115}}) {
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|   assertTrue('myprop' in x);
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|   assertEquals(2115, x.myprop);
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|   assertEquals(2115, global_side_assignment);
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|   called = true;
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| }
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| f1({});
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| assertTrue(called);
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| assertEquals(2115, global_side_assignment);
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| 
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| called = false;
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| global_side_assignment = undefined;
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| function f2({x = {myprop: global_side_assignment} = {myprop: 2115}}) {
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|   assertEquals(3000, x);
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|   called = true;
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| }
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| f2({x: 3000});
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| assertTrue(called);
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| assertEquals(undefined, global_side_assignment);
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