676602 - Multiple breakpoints per line

Status: RESOLVED FIXED

(DevTools :: Debugger, defect, P4)

Description

[Panos Astithas (he/him) [:past] (please ni?)]

The jsdbg2 work in SpiderMonkey allows multiple breakpoints to be set in a single line, since there can be many bytecodes in there. We should provide a way for the debugger UI to accomplish that. 

This would also require to somehow resolve the ambiguity discussed in the remote protocol's response with multiple breakpoint actors (do we pause in all those handlers, or just in the last one? How do those handlers get references to the others?).

Comment 1

[Nick Fitzgerald [:fitzgen] [⏰PST; UTC-8]]

FWIW, the protocol and server support this, we just don't have a good UI for it. Maybe Darrin can chime in?

Comment 2

[Mark Goodwin [:mgoodwin]]

(In reply to Nick Fitzgerald [:fitzgen] from comment #1)
> FWIW, the protocol and server support this, we just don't have a good UI

Maybe a good starting point would be exposing it when the user does a "Prettify Source"?

Comment 3

[Nick Fitzgerald [:fitzgen] [⏰PST; UTC-8]]

(In reply to Mark Goodwin [:mgoodwin] from comment #2)
> (In reply to Nick Fitzgerald [:fitzgen] from comment #1)
> > FWIW, the protocol and server support this, we just don't have a good UI
> 
> Maybe a good starting point would be exposing it when the user does a
> "Prettify Source"?

Once the source is prettified, you should be able to set breakpoints on each of those new lines (we are source mapping), but still not multiple breakpoints on the same line. Is this what you need?

Comment 4

[Mark Goodwin [:mgoodwin]]

That would be good - though it doesn't seem to be happening in a current nightly (at least on the app I'm testing). Will investigate further.

Comment 5

[Hallvord R. M. Steen [:hallvors]]

> Once the source is prettified, you should be able to set breakpoints on each
> of those new lines

I haven't tested bleeding edge devtools versions - but certain obfuscation/minifier tools are now using commas for semicolons for many constructs. I assume even prettifying doesn't help here? Can you give me a way to set a breakpoint on the statement calling c() here?

(foo&&a(),b(),c()),d(),(bar&&e(),f())


> (we are source mapping), but still not multiple
> breakpoints on the same line. Is this what you need?

Yes, if this is what it takes when statements are comma-chained.. :-) This can also be solved with special stuff in the prettifier, I guess, but wrapping and indenting such code can get pretty complex. How would you like to see this wrapped?

for(var i;foo&&(bar()&&i<50)||foobar();i++)

A feature that makes each JS statement separately focusable and lets you double-click (or equivalent keyboard command) a statement to add a breakpoint there would make this easier.

Comment 6

[David Walsh :davidwalsh]

We've implemented Column Breakpoints in the DevTools debugger, behind a pref, which should be turned to true shortly. Closing as I believe that's what this bug is requesting.