Chakra should throw an exception when evaluate an invalid "for" statement

[igor-simoes]

Hi everyone,
I found an inconsistency when try to evaluate a "for" statement without the body statement.

OS: Ubuntu 16.04 x64
Chakra: 1.10.0.0-beta

Step to reproduce:

first = "for (i = 0; i < 3; i++);"
print (eval ( first ) )

second = "for (i = 0; i < 3; i++)"
print (eval ( second ) )

Actual results:

undefined
undefined

Expected results:

undefined
SyntaxError: Unexpected end of input

I ran the second statement without eval function and Chakra passes without throw an Exception also.

for (i = 0; i < 3; i++)

V8, SpiderMonkey and JavascriptCore works as expected.

cinfuzz

[fatcerberus]

Sounds like overzealous ASI.

[infinnie]

Reproduced on Edge.
OS: Windows
User agent:

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/17.17134

[rhuanjl]

Was thinking of trying to fix this but first I took a quick look at it with eshost:
Firstly without eval none of the 4 throw an error:

# Source
for(var i = 0; i < 10; ++i)

#### Chakra, JavaScriptCore, SpiderMonkey, V8 --harmony

Then with eval CC still throws no error but the others do throw errors:

## Source
eval("for(var i = 0; i < 10; ++i)");

#### Chakra


#### V8 --harmony
SyntaxError: Unexpected end of input

#### SpiderMonkey
SyntaxError: expected expression, got end of script:

#### JavaScriptCore
SyntaxError: Unexpected end of script

It seems that with no eval present all 4 engines happily apply ASI whereas without an eval only CC applies ASI - IMO CC's behaviour seems more logical than the other 3 engines here. I don't know the correct answer per spec though; but for now I won't try to submit a "fix" as not confident that current behaviour is wrong.

[fatcerberus]

I don’t think ASI should apply here at all: if you put the offending code into a function block then all engines will produce a syntax error.