UndefVarError from getfield(Main, Symbol("##xx#xx")) symbols not defined

[baggepinnen]

(On julia v1.2) I'm trying snoopcompile out for the first time. When snooping while running the tests of my package, the generated precompile file contains a lot of code with getfield(Main, Symbol("##xx#xx")), like this

precompile(Tuple{typeof(MonteCarloMeasurements.gradient), getfield(Main, Symbol("##28#95")), MonteCarloMeasurements.Particles{Float64, 500}})

which causes

julia> using MonteCarloMeasurements
[ Info: Recompiling stale cache file /local/home/fredrikb/.julia/compiled/v1.2/MonteCarloMeasurements/tHYBD.ji for MonteCarloMeasurements [0987c9cc-fe09-11e8-30f0-b96dd679fdca]
ERROR: Error while loading expression starting at /local/home/fredrikb/.julia/dev/MonteCarloMeasurements/src/MonteCarloMeasurements.jl:89
caused by [exception 1]
UndefVarError: ##28#95 not defined
Stacktrace:
 [1] _precompile_() at /local/home/fredrikb/.julia/dev/MonteCarloMeasurements/src/precompile_MonteCarloMeasurements.jl:11

I guess that the line in runtests.jl that lead to this is somewhere here
Am I doing something wrong?

For reference, the code used to generate the precompile file is below

using SnoopCompile
SnoopCompile.@snoopc "/tmp/robust_opt_compiles.log" begin
    using MonteCarloMeasurements, Pkg
    include(joinpath(dirname(dirname(pathof(MonteCarloMeasurements))), "test", "runtests.jl"))
end
data = SnoopCompile.read("/tmp/robust_opt_compiles.log")
pc = SnoopCompile.parcel(reverse!(data[2]))
SnoopCompile.write("/tmp/precompile", pc)

[timholy]

When I first wrote this package, I didn't realize that precompilation only saves inference time. So the @snoopc mechanism, while seemingly more sophisticated, is prioritizing the wrong stuff. If you're on Julia 1.2, I highly recommend @snoopi. Personally, I then write the corresponding precompile statements manually. Note that because of the issue diagnosed in JuliaLang/julia#31466 (which is also partway towards a fix), many things fail to precompile (unfortunately).

But I will try to fix this. Those ##28##95 objects correspond to anonymous functions, and the numbering is not consistent from session to session.