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Missing error for a destructuring pattern inside a rest binding element / rest parameter #2519
Description
The following is not allowed by the ES6 grammar:
function foo(...[a]) { }
var [...[b, c]] = [0, 1, 2];The relevant grammar production is:
BindingRestElement[Yield, GeneratorParameter] :
[+GeneratorParameter] ... BindingIdentifier[Yield]
[~GeneratorParameter] ... BindingIdentifier[?Yield]
And a BindingIdentifier does not include a binding pattern.
Activity
Adjust getTypeFromArrayBindingPattern to return an array if inside a …
yuit commentedon Apr 12, 2015
Following code:
causes crash when compiling:
D:\TS\built\local\tsc.js:26338
emitDestructuring(p, false, tempParameters[tempIndex
^
TypeError: Cannot read property '0' of undefined
at D:\TS\built\local\tsc.js:26338:71
at Object.forEach (D:\TS\built\local\tsc.js:693:30)
at emitDefaultValueAssignments (D:\TS\built\local\tsc.js:26334:24)
at emitFunctionBodyPreamble (D:\TS\built\local\tsc.js:26521:17)
at emitBlockFunctionBody (D:\TS\built\local\tsc.js:26588:17)
at emitSignatureAndBody (D:\TS\built\local\tsc.js:26506:21)
at emitFunctionDeclaration (D:\TS\built\local\tsc.js:26450:17)
at emitJavaScriptWorker (D:\TS\built\local\tsc.js:28256:32)
at emitNodeWithoutSourceMap (D:\TS\built\local\tsc.js:28146:17)
at emitLinesStartingAt (D:\TS\built\local\tsc.js:24527:21)
Disallow binding patterns in binding rest elements (fixes #2519)
rauschma commentedon Dec 28, 2015
ES7/ES2016 will allow this pattern: https://tc39.github.io/ecma262/#sec-destructuring-binding-patterns
It was inconsistent with destructuring assignment that has always allowed it: http://www.ecma-international.org/ecma-262/6.0/#sec-destructuring-assignment
DanielRosenwasser commentedon Dec 28, 2015
Thanks for the heads up Axel Rauschmayer (@rauschma)! I've filed #6275.