Local variables are collapsed in annoying ways

[jrieken]

I have a launch config that attaches to an extension host and often (this seems somewhat random) the variable nodes are collapsed in super annoying ways (hello paper cuts). The first screen shot shows the view after hitting the first breakpoint. Not sure what/if something goes wrong but I think in no universe it makes sense to show all variables nodes as collapsed. The second screen shot is after stepping a bit and the variables view doesn't "follow" - I am already three blocks further down but nothing is reveal/expanded which makes this whole thing painful to work with.

[isidorn]

@jrieken thanks for providing great feedback

What we do:

1. If every scope is collapsed and the first one is not expensive we automatically expand it
2. between steps we always preserve the expansions state

I believe that 1) we can improve that we auto expand all non expensive scopes. Global scope is for example marked as expensive.
2) should work always, @jrieken let me know if this is not working sometimes for you

For some smarter auto expensions we could look at the Scope Source and for example automatically expand all scopes that match the currently active file (which have not been explicltly collapsed by the user). And this approach I like the best. Not sure thuogh how much debug adapters provide exact Scope Source information

@weinand @roblourens @connor4312 let me know what you think

[jrieken]

between steps we always preserve the expansions state

But that doesn't work when hitting the same breakpoint repeatedly, right?

[weinand]

@isidorn we are preserving expansion state between steps based on the "sourceReference" returned from the DA, correct? If these "sourceReference" are not reused between steps, we might lose the expansion state.

@jrieken are you using preview js-debug?

[jrieken]

yes - this is insiders and believe js-debug the default there

[isidorn]

@jrieken should work when hitting the same breakpoint repeatedly
@weinand we preserve the state based on scope name and it's index in the Scopes array which we get from the stack frame. We could also use the sourceReference instead of the index but that proved less stable in practice than the index. Code pointer

And yes, js-debug is the default in insiders.

[weinand]

@isidorn "scope name and its index in the Scopes array" sounds much better than sourceReference.
But could it be that @jrieken runs into the issue that the "scope index" changes?

[isidorn]

It could be looking at the attached picture, there are 3 new block scopes added between pictures.

[jrieken]

Attached video shows the randomness that I am observing

Mar-23-2020 15-45-48.mp4.zip