1565578 - 'Step in' exits function

Status: RESOLVED FIXED

(DevTools :: Debugger, defect, P1)

Description

[Oriol Brufau [:Oriol]]

1. Run this code in the console:

   (function(){
     debugger;
     var a = 1;
     var b = 2;
   })();
   

2. The debugger pauses at debugger;
3. Step in

Expected: the debugger pauses at var a = 1;
Result: the debugger pauses at })();

Regression window: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=b7ae64d5ac774ce9054e8aa3431ecd992594447b&tochange=0ab76cc4232f56936e1a2609823f0c13272ca449

Comment 1

[Jason Laster [:jlast]]

Attachment: Bug 1565578 - 'Step in' exits function. r=loganfsmyth

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/76a5046906d7
'Step in' exits function. r=loganfsmyth

Comment 3

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/76a5046906d7

Comment 4

[Ryan VanderMeulen [:RyanVM]]

Is this something we should consider uplifting to Beta for Fx69 or can it ride to release with Fx70?

Comment 5

[Jason Laster [:jlast]]

I don't think it is important enough.

Comment 6

[Alexandre Poirot [:ochameau]]

(In reply to Jason Laster [:jlast] from comment #5)

I don't think it is important enough.

Is it? It sounds like a very disturbing breakage to have around breakpoints. One which can make developer quite unhappy regarding our tools quality. I thought that breakpoint correctness was a top level goal for the debugger?
Now, it is very surprising for me to see how long it took to get a report about this breakage, which may be the one reason to not consider this as important.

Comment 7

[Jason Laster [:jlast]]

Harald and I discussed this last week and it is a difficult call.

This bug makes it impossible to step through console evaluated code. On the other hand, this fix is somewhat risky and could affect much more common use cases.

Given that, I am hesitant to uplift the changeset and have a small window to address any unforseen issues before they go out to release.

Comment 8

[Alexandre Poirot [:ochameau]]

A(In reply to Jason Laster [:jlast] from comment #7)

This bug makes it impossible to step through console evaluated code. On the other hand, this fix is somewhat risky and could affect much more common use cases.

Ah sorry. I was mislead by the bug title. I missed that it was only when the code we step through is from a console evaluation. I thought it was more generic than that.

I now better understand your call! It sounds sensible to me as well.