improve inferrability of prune_graph! (#3202)

* improve inferrability of `prune_graph!`

This fixes some invalidations when loading HDF5.jl

* update comment

Co-authored-by: Kristoffer Carlsson <kcarlsson89@gmail.com>
(cherry picked from commit 0d5230b)

src/Resolve/graphtype.jl

@@ -1439,7 +1439,12 @@ function prune_graph!(graph::Graph)
  return pvers0[vmsk0[1:(end-1)]]
  end
  new_pvers = [compute_pvers(new_p0) for new_p0 = 1:new_np]
- new_vdict = [Dict(vn => v0 for (v0,vn) in enumerate(new_pvers[new_p0])) for new_p0 = 1:new_np]
+
+ # explicitly writing out the following loop since the generator equivalent caused type inference failure
+ new_vdict = Vector{Dict{VersionNumber, Int}}(undef, length(new_pvers))
+ for new_p0 in eachindex(new_vdict)
+ new_vdict[new_p0] = Dict(vn => v0 for (v0,vn) in enumerate(new_pvers[new_p0]))
+ end
 
  # The new constraints are all going to be `true`, except possibly
  # for the "uninstalled" state, which we copy over from the old