1241966 - Better error when assigning to primitives in strict mode

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Tom S [:evilpie]]

Jason:
> But what is up with that error message?
> 
>     typein:1:15 TypeError: can't assign to properties of (new
> Boolean(true)): not an object
> 
> WAT!

I looked into this before and the way we delay reporting the error message with ObjectOpResult probably requires some special casing for this.

Comment 2

[Jason Orendorff [:jorendorff]]

Low priority but I'd like to do this...

Comment 3

[Tom S [:evilpie]]

Looking at nbp's counters for error messages (https://nbp.github.io/arewedocumentedyet/), this is actually relatively high.

Comment 4

[Tom S [:evilpie]]

Attachment: Unbox non-object receiver for error reporting

We already know the the value originally was a primitive, so we might as well just unbox it. This is a bit of a hack, but at least we don't need to rejigger ObjectOpResult for this special case.

Comment 5

[Jan de Mooij [:jandem]]

Comment on attachment 8912192 [details] [diff] [review]
Unbox non-object receiver for error reporting

Review of attachment 8912192 [details] [diff] [review]:
-----------------------------------------------------------------

Nice. Add a test for a number of different primitives, to make sure we don't regress this? Checking the exact error message is fine probably.

Comment 6

[Tom S [:evilpie]]

Attachment: v2 Unbox non-object receiver for error reporting

Sorry I should have written a test for this before. So I found out that we need to allow unboxing Symbol objects as well. This shouldn't change any behavior, because other callers check the object class before unboxing.

Comment 7

[Jan de Mooij [:jandem]]

Comment on attachment 8913993 [details] [diff] [review]
v2 Unbox non-object receiver for error reporting

Review of attachment 8913993 [details] [diff] [review]:
-----------------------------------------------------------------

Good catch.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/417c277c6853
Unbox non-object receiver for better error reporting. r=jandem

Comment 9

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/417c277c6853