Cannot retrieve scope data from scopes outside of the current analysis context with concurrent solver enabled

[jochembroekhoff]

Bug description
The stx-get-scopegraph-data API method returns the empty list if the given scope is not part of the current analysis context.

Versions
Spoofax version: 2.5.16.
Statix setup: multi-file, concurrent solver enabled.

Steps to reproduce the behavior

• Create two files where the second file somehow references a scope of the first file.
• The scope must be declared in the first file and have some data on it declared.
• When transforming the second file, retrieve this particular Scope/2 instance.
• Retrieve the analysis context using stx-get-ast-analysis, for a term of the second file.
• Call the API method, e.g. <stx-get-scopegraph-data(|a, "identifier/of!relation")> s.
• Observe that the result is always [].

Observed behavior
The result is the empty list.

Expected behavior
The result is not necessarily the empty list, but the actual relevant members.

Additional context
Original Slack thread: https://slde.slack.com/archives/C7254SF60/p1649660409194699.

Workaround

stx-get-scopegraph-data-ext(|a, rel) = ?s
; stx-get-scopegraph-data(|a, rel)
; try(
    ?[]; !s
    // extract the resource identifier from the scope and drop the "/./" prefix
  ; where(Scope(string-as-chars(drop(|3)) => resource, id))
    // attempt to retrieve the analysis state from the external scope
  ; where(a' := <stx-get-ast-analysis> (){TermIndex(resource, -1)})
    // re-execute in the external context
  ; stx-get-scopegraph-data(|a', rel)
  )

[AZWN]

As discussed, this is an important issue to solve. Thanks for reporting!