Cannot evaluate expression on value definition

[ckipp01]

I originally brought this up in scalameta/metals#2959 while testing out the new code evaluation in Metals. I noticed that given a situation where you set a breakpoint before a variable is assigned, any evaluation is then blocked since it seems to not find that variable. A picture is worth a thousand words so you can see what I mean here:

Notice that I'm stopped on the line containing val y = x * 3. I'm just trying to evaluate 3 * 6 here, and I'd expect that to work instead of getting the message about not found: value y.

The same thing happens if you try to access another variable that should already be assigned like x in this example:

Notice that it is there when looking at the variables, but when I try to access it via just x where the expressions are entered at the bottom, I again see the message.

I tested this with the pr in Metals here: scalameta/metals#2959 while using nvim-metals, which integrates with nvim-dap.

As a total aside, great job on this so far. It's fantastic to see this working. In the above examples if I just step over once, then everything works.

[tgodzik]

I can still reproduce the issue in Metals, can you take a second look @tdudzik ?

[ckipp01]

I can still reproduce the issue in Metals, can you take a second look @tdudzik ?

Just a sanity check, but make sure you have the new bloop that it brought in running and not the old one. I've made that mistake more than once when testing this out 😆

[tdudzik]

Actually, it doesn't always work. It seems there were two issues with that case and I've fixed only one of them. The other one should be fixed soon.

[adpi2]

@tdudzik Can you share the reproduction case?

[tdudzik]

@adpi2 it seems that it works only when a value/variable is defined but it's not used, so e.g.:
it's going to work:

val a = 1 // breakpoint
println("Hello, World!")

it's not going to work:

val a = 1 // breakpoint
println(a)

The reason is that in InsertExpression compilation phase expression is wrapped in a block so the second example will be converted to something like this:

{
1 + 2 // expression
val a = 1 
}
println(a)

and then the value a is not accessible in the line println(a) and because of that error is returned.

[tgodzik]

Do we need to have val a = 1 in the block? Could we move it outside it?