Fix exports of undefined/missing/conditionally defined symbols

[m-j-w]

It appears in #20486, Base.Parallel has been renamed to Base.Distributed, but is
still exported. Thus, the export in base/exports.jl is not valid anymore. In
particular, when doing e.g. a [ s for s in names(Base) if typeof(getfield(Base,s))<:Function] an UndefVarError is thrown on 'Parallel'.

julia> [ s for s in names(Base) if typeof(getfield(Base,s))<:Function]
ERROR: UndefVarError: Parallel not defined
Stacktrace:
 [1] advance_filter(::##6#8, ::Array{Symbol,1}, ::Tuple{Bool,Symbol,Int64}) at ./iterators.jl:270
 [2] next at ./generator.jl:44 [inlined]
 [3] grow_to!(::Array{Symbol,1}, ::Base.Generator{Base.Iterators.Filter{##6#8,Array{Symbol,1}},##5#7}, ::Tuple{Bool,Symbol,Int64}) at ./array.jl:475
 [4] grow_to!(::Array{Union{},1}, ::Base.Generator{Base.Iterators.Filter{##6#8,Array{Symbol,1}},##5#7}, ::Tuple{Bool,Symbol,Int64}) at ./array.jl:483
 [5] grow_to!(::Array{Symbol,1}, ::Base.Generator{Base.Iterators.Filter{##6#8,Array{Symbol,1}},##5#7}) at ./array.jl:468
 [6] collect(::Base.Generator{Base.Iterators.Filter{##6#8,Array{Symbol,1}},##5#7}) at ./array.jl:412

[tkelman]

If we've gone several weeks without this breaking anything, do we even need to export the new Distributed module name?

[m-j-w]

It also appears there are more symbols being exported but undefined in Base:

julia> for m in Base.Docs.modules
         for s in names(m)
            try
               getfield(m,s)
            catch e
               println("Module: $(m).$(string(s)) gives ", e)
            end
          end
       end

gives

Module: Base.Filesystem.JL_O_RANDOM gives UndefVarError(:JL_O_RANDOM)
Module: Base.Filesystem.JL_O_SEQUENTIAL gives UndefVarError(:JL_O_SEQUENTIAL)
Module: Base.Filesystem.JL_O_SHORT_LIVED gives UndefVarError(:JL_O_SHORT_LIVED)
Module: Base.Filesystem.JL_O_TEMPORARY gives UndefVarError(:JL_O_TEMPORARY)
Module: Base.MPFR.big_str gives UndefVarError(:big_str)
Module: Base.dSFMT.win32_SystemFunction036! gives UndefVarError(:win32_SystemFunction036!)
Module: Base.SparseArrays.dense gives UndefVarError(:dense)

I didn't check them more closely, yet. But from a quick look seems they are all exported but not actually defined.

Maybe an automated test for undefined exports would be helpful.

I could take a look later and update the PR.

[StefanKarpinski]

Maybe an automated test for undefined exports would be helpful.

Yes, we definitely should have this. It seems like it might be good for an export that's undefined by the time a module is closed would be sensible. @JeffBezanson: is there a use case for undefined exports that's the reason we don't error or warn in that situation?

[ViralBShah]

Cc @amitmurthy

[amitmurthy]

If we've gone several weeks without this breaking anything, do we even need to export the new Distributed module name?

Let's keep the Distributed module name export for now. We should remove the import and re-exports of distributed API from Base in the next iteration when an explicit using Distributed will be required.

[m-j-w]

I've updated the PR to fix the missing exports (and changed the title accordingly):

• module Parallel has been renamed to Distributed --> export renamed.
• big_str is not defined in mpfr.jl, but rather in int.jl as macro @big_str --> removed export.
• win32_SystemFunction036! is only available on windows --> conditionally exported.
• dense is not defined in module SparseArray --> removed export.
• JL_O_RANDOM etc. are never defined or used in module FileSystem --> removed export.

Locally, I've got now no erroneous exports anymore.
Please check.

[tkelman]

these are likely platform dependent, see src/file_constants.h

[m-j-w]

When grep-ing for those, I don't see them ever being used in a context of the Julia runtime. Only in that header file. What to do ?

[yuyichao]

Keep them.

[m-j-w]

With the builds failing on Appveyor, it's clear that the 'random' export didn't work as intended, and that the JL_O_* indeed are platform dependent (also found them in mingw provided fcntl.h, but only there).
I'll try to get my Windows build environment up again to test locally first.

[m-j-w]

Filesystem and random number generator are a bit tricky since I didn't get Julia's dependencies to compile correctly on Windows. Thus, I removed those failing conditional exports for now from the PR.

• module Parallel has been renamed to Distributed --> export renamed.
• big_str is not defined in mpfr.jl, but rather in int.jl as macro @big_str --> removed export.
• dense is not defined in module SparseArray --> removed export.

The following conditionally required exports (Windows only) are not adressed anymore:

• win32_SystemFunction036! is only available on windows --> kept for now..
• JL_O_RANDOM , JL_O_SHORT_LIVED etc. are only available on Windows --> kept for now.

I believe this now to be correct and the tests pass.

[amitmurthy]

Is this still a RFC/WIP or is it done?

[m-j-w]

Should be done.

[amitmurthy]

Thanks.