[Webkit-unassigned] [Bug 136445] New: Assignment to a property on a primitive in strict mode should not throw

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=136445

           Summary: Assignment to a property on a primitive in strict mode
                    should not throw
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: Unspecified
        OS/Version: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: JavaScriptCore
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: ljharb at gmail.com


`(function () { "use strict"; 3.0.a = true; }())`
`(function () { "use strict"; 'foo'.a = true; }())`
`(function () { "use strict"; true.a = true; }())`

None of these throw exceptions in Chrome, Firefox, Opera - but in Safari 7.1, these all throw a TypeError "Attempted to assign to readonly property.".

According to the ES5 spec ( https://es5.github.io/#C ) and ES6 spec ( https://people.mozilla.org/~jorendorff/es6-draft.html#sec-strict-mode-of-ecmascript ), Safari is in error here. In addition, one of the TC39 spec maintainers confirmed via Twitter that this is a Safari bug ( https://twitter.com/awbjs/status/506687103506587648 )

Steps to Reproduce:
Run any of the JS functions in the console, or any other JS mechanism:

(function () { "use strict"; 3.0.a = true; }())

(function () { "use strict"; 'foo'.a = true; }())

(function () { "use strict"; true.a = true; }())

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