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iterator-destructuring-property-reference-target-evaluation-order.js (2169B)

      1 // Copyright (C) 2017 André Bargull. All rights reserved.
      2 // This code is governed by the BSD license found in the LICENSE file.
      3 
      4 /*---
      5 esid: sec-runtime-semantics-iteratordestructuringassignmentevaluation
      6 description: >
      7    Ensure correct evaluation order when destructuring target is property reference.
      8 info: |
      9    12.15.5.3 Runtime Semantics: IteratorDestructuringAssignmentEvaluation
     10 
     11    AssignmentElement : DestructuringAssignmentTarget Initializer
     12 
     13    1. If DestructuringAssignmentTarget is neither an ObjectLiteral nor an ArrayLiteral, then
     14        a. Let lref be the result of evaluating DestructuringAssignmentTarget.
     15        b. ReturnIfAbrupt(lref).
     16    2. If iteratorRecord.[[Done]] is false, then
     17        a. Let next be IteratorStep(iteratorRecord.[[Iterator]]).
     18        ...
     19    3. If iteratorRecord.[[Done]] is true, let value be undefined.
     20    ...
     21    5. Else, let v be value.
     22    ...
     23    8. Return ? PutValue(lref, v).
     24 features: [Symbol.iterator]
     25 includes: [compareArray.js]
     26 ---*/
     27 
     28 
     29 var log = [];
     30 
     31 function source() {
     32    log.push("source");
     33    var iterator = {
     34        next: function() {
     35            log.push("iterator-step");
     36            return {
     37                get done() {
     38                    log.push("iterator-done");
     39                    return true;
     40                },
     41                get value() {
     42                    // Note: This getter shouldn't be called.
     43                    log.push("iterator-value");
     44                }
     45            };
     46        }
     47    };
     48    var source = {};
     49    source[Symbol.iterator] = function() {
     50        log.push("iterator");
     51        return iterator;
     52    };
     53    return source;
     54 }
     55 function target() {
     56    log.push("target");
     57    return target = {
     58        set q(v) {
     59            log.push("set");
     60        }
     61    };
     62 }
     63 function targetKey() {
     64    log.push("target-key");
     65    return {
     66        toString: function() {
     67            log.push("target-key-tostring");
     68            return "q";
     69        }
     70    };
     71 }
     72 
     73 ([target()[targetKey()]] = source());
     74 
     75 assert.compareArray(log, [
     76    "source", "iterator",
     77    "target", "target-key",
     78    "iterator-step", "iterator-done",
     79    "target-key-tostring", "set",
     80 ]);
     81 
     82 reportCompare(0, 0);