469402 - Strange scoping with array comprehensions

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Jesse Ruderman]

js> print(uneval([j for each (i in [[1],[2],[3,4]]) for each (j in i)]));
[1, 2, 3, 4]
js> print(uneval([7 for each (j in i) for each (i in [[31]])]));
[]
js> print(uneval([7 for each (j in i) for each (a in [31])]));
typein:3: ReferenceError: i is not defined

I think the second line should also throw "ReferenceError: i is not defined", since "i" is the loop variable for the inner loop and the outer loop tries to reference it.  In other words, I expect nested array-comprehension loops to behave more like nested statement-level for-loops:

js> for each (let j in i) for each (let i in [[31]]) { 7; }
typein:1: ReferenceError: i is not defined

Comment 1

[André Bargull [:anba]]

JS1.8 generator comprehensions were removed in bug 1220564, resolving as Won't
Fix.