382502 - Round-trip line-breaking change with genexp

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine, defect)

Description

[Jesse Ruderman]

This is strange.. there isn't any change to parenthesization, but there's a change to line-breaking.

js> f = function(){ while(t && (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa for (g in b))) {} }
function () {
    while (t &&
        aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa for (g in b)) {
    }
}

js> eval("(" + f + ")")
function () {
    while (t && aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa for (g in b)) {
    }
}

Comment 1

[Ryan VanderMeulen [:RyanVM]]

The behavior has changed.

js> f = function(){ while(t && (aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa for (g in b))) {} }
(function () {while (t && true) {}})

js> eval("(" + f + ")")
(function () {while (t && true) {}})

Comment 2

[Jesse Ruderman]

That's quite an optimization.

I guess I'll call this bug WFM, and file a new bug if I hit another round-trip line-breaking change.

Comment 3

[Gary Kwong [:gkw] [:nth10sd] (NOT official MoCo now)]

(In reply to Jesse Ruderman from comment #2)
> That's quite an optimization.
> 
> I guess I'll call this bug WFM, and file a new bug if I hit another
> round-trip line-breaking change.

Yup!