Occurs on OSX and Windows 7

Tested on Windows 7 using chrome latest stable M49-49.0.2623.110 by loading the provided html file and observed the error displayed in the console as shown in the above snap shot.

Tested the same on chrome M45-45.0.2442.0 and observed no error instead of that displayed result saying "no errors yet 9, no errors yet 16" as seen in the snap shot.

djcavanagh@ Could you please confirm is this is the expected behavior of this issue? If yes, please let us know it will be helpful to investigate this issue further.

thanks!

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Yes, that is the expected behavior.

Thanks

Thank you for providing more feedback. Adding requester "brajkumar@chromium.org" for another review and adding "Needs-Review" label for tracking.

For more details visit https://sites.google.com/a/chromium.org/dev/issue-tracking/autotriage - Your friendly Sheriffbot

The stricter syntax checking killed my program having this code:

function something() {
 var myfunc1;
 var myfunc2;

 function myfunc1() {
  myfunc2();
 }

 function myfunc2() {
  //...
 }
}

I used the var myfunc declarations, because JSLINT does not allow using functions defined after the function call.

Without the forward declaration, the code structure gets messy and writing functions calling each other is no longer possible.

And I really think Google should not make changes to the JS parser that kill legacy programms at all.

Thanks

Bisect Information:
=====================
Good build: 49.0.2613.0 
Bad Build : 49.0.2615.0 

Change Log URL: https://chromium.googlesource.com/chromium/src/+log/58c142c6eccd0287edcf0194391f785e45a8de92..a4231e4994a90b513122bdb9a58069d26938849f

v8-autoroll:
https://chromium.googlesource.com/v8/v8/+log/5041f175..aca25b0c

From the above V8 log suspecting below

Review URL: https://codereview.chromium.org/1561603002

mythria@ - Assigning to you, Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Thanks!

 https://codereview.chromium.org/1561603002 may not be the cause of this problem. It is behind a flag that is not enabled by default.

Reduced test case for reproducing with d8. 

function f() {
  var a;
  function a() { // This works
  }

 {
   var b;
   function b() { // This gives syntax error.
   }
 } 
}
f();

@admak could this be related to recent changes with legacy constants?

This is due to our changes for ES2015 sloppy mode block scoping of function declarations, but it looks like we might have a bug. Investigating...

To the reporter: Is this causing issues in a production website you're aware of? Or is it simply the mismatch with JSLINT behavior that you're reporting? If the latter, I'd recommend taking it up with JSLINT, as using vars to make the linter "happy" doesn't make much sense to me: function declarations are always hoisted to the top of their scope.

We are following the spec here (to be exact, the second bullet of https://tc39.github.io/ecma262/#sec-block-static-semantics-early-errors). Other browsers have a mish-mash of behaviors.

Firefox: doesn't throw, but does for the very similar "{var x; let x;}". In Nightly, does throw (they're now following the spec too, apparently).
Edge: doesn't throw for this case or for "{var x; let x;}"
WebKit (nightly): same as Edge

Moving this nonessential bug to the next milestone.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

This issue has been moved once and is lower than Pri-1. Removing the milestone.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Marking as WontFix since the reported behavior is per spec.