Fix incorrect mutation-after-consumption assertions for Array push and unshift
#397
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… bug Simply doing a `.push()` or `.unshift()` call after creating the Array during construction of a component is enough to trigger the issue. This will be red in CI; the follow-on commit will fix it.
For these methods, `Array` itself immediately gets the `.length` to return after invoking them. Thus, if we are reading `.length`, it may be a normal user-triggered read, or it may be a read triggered by Array itself. In the latter case, it is because we have just done `.push()` or `.unshift()`; in that case it is safe *not* to treat reading `.length` as a *read* operation, since calling `.push()` or `.unshift()` cannot otherwise be part of a "read" operation safely, and if done during an *existing* read (e.g. if the user has already checked `.length` *prior* to this), that will still trigger the assertion. Accordingly, set the new flag to `true` when calling `.push()` or `.unshift()`, and then clear it during the immediately-following `.length` check.
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Looks like we'll have to fix up CI first (separately!) but it does in fact work! |
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For these methods,
Arrayitself immediately gets the.lengthto return after invoking them. Thus, if we are reading.length, it may be a normal user-triggered read, or it may be a read triggered by Array itself. In the latter case, it is because we have just done.push()or.unshift(); in that case it is safe not to treat reading.lengthas a read operation, since calling.push()or.unshift()cannot otherwise be part of a "read" operation safely, and if done during an existing read (e.g. if the user has already checked.lengthprior to this), that will still trigger the assertion.This PR:
Introduces a simple failing test. Simply doing a
.push()or.unshift()call after creating the Array during construction of a component is enough to trigger the issue.Introduces a flag, which the proxy's
get()sets totruewhen calling.push()or.unshift(), and then clear it during the immediately-following.lengthcheck.Fixes #29.