invalid redefinition of constant from parametric type

[marius311]

Basically just this issue, which ClobberringReload seems to suffer from also: malmaud/Autoreload.jl#23

If the file getting reloaded contains a parametric type, you get an "invalid redefinition of constant" error. I've tested this on Julia 0.5 and current master (0942244).

[cstjean]

Yes, this is really unfortunate, but the good news is that the issue has been solved on julia-master by #17618 (though I haven't tested it). I'm hopeful that this can be backported to 0.5.1, and will be suggesting it when the time comes.

[marius311]

Ah, good to know, thanks. Is there any way to prevent ClobberingReload from trying to reevaluate those types, as a workaround until that fix hits a stable Julia version?

[cstjean]

We could follow @malmaud's suggestion to strip out the type definition from the AST before passing it to eval. There are some issues with that:

• Changes to the constructors will be ignored
• It won't work if the type definition is inside a macro expansion

But that's fine, I suppose. We could have a global boolean to turn it on. PRs welcome.

[cstjean]

And we'd have to expand the includes to cover their parametric types...

[rdeits]

I'm actually still getting this error on the latest v0.6-dev, unfortunately.

[cstjean]

Can anyone please check if executing

immutable X{T}
   a::T
end

twice at the REPL on 0.6 triggers an error?

[rdeits]

Yeah, it does:

               _
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 _/ |\__'_|_|_|\__'_|  |  Commit 71f6bc9 (0 days old master)
|__/                   |  x86_64-apple-darwin13.4.0

julia> immutable X{T}
          a::T
       end

julia> immutable X{T}
          a::T
       end
ERROR: invalid redefinition of constant X

[cstjean]

Sorry that I didn't handle it for 0.5, but this is fixed on 0.6 thanks to changes in Base 🎉

[skariel]

this is not solved for self referential types. In Julia 0.6:

struct ABC
    z::ABC
    function ABC()
        n = new()
        n.z = n
        n
    end
end

struct ABC
    z::ABC
    function ABC()
        n = new()
        n.z = n
        n
    end
end

results in:

invalid redefinition of constant ABC

Stacktrace:
 [1] include_string(::String, ::String) at ./loading.jl:515

I'll open a new issue

[skariel]

see new issue here: #24270

[cstjean]

Have you tried Revise.jl? I'm probably going to deprecate ClobberingReload.jl, because Revise.jl is pretty much uniformly nicer. It doesn't suffer from the struct-redefinition problem.

Thoughts?

[rdeits]

For my part, I've stopped using ClobberingReload in favor of Revise. It is pretty magical 😄