edit and less fail for stdlib functions in distribution binaries

[RalphAS]

The trouble is that file names in stdlib methods are (inappropriate) absolute paths:

julia> ml=methods(edit)
# 5 methods for generic function "edit":
[1] edit(path::AbstractString) in InteractiveUtils at 
/buildworker/worker/package_linux64/build/usr/share/julia/site/v0.7/InteractiveUtils/src/editless.jl:37
#etc.

julia> less(edit,(AbstractString,))
/buildworker/worker/package_linux64/build/usr/share/julia/site/v0.7/InteractiveUtils/src/editless.jl: 
No such file or directory

We can cheat:

julia> ml.ms[1].file=Symbol("../site/v0.7/InteractiveUtils/src/editless.jl");
julia> less(edit,(AbstractString,)) # this works

This is troublesome for those of us who want to consult "The Real Documentation" but didn't build from source.

(edited to fit more useful issue title)

[RalphAS]

Note that this problem can be circumvented by locally rebuilding the system image.

[vtjnash]

If we want to kill this with a bazooka, see rust-lang/rust#38322 (comment) and -fdebug-prefix-map

[vtjnash]

dup #21921 (probably)

[RalphAS]

The distinction from #21921 is that in out-of-tree builds stdlib gets good file references but base is problematic, whereas in official binary distributions it's the other way around. The file fields for base methods are handled specially, perhaps something similar could be done for stdlib.

[carstenbauer]

Since this has been marked as priority, what are the chances that we'll have correct paths in 1.1.0? Can this be added in 1.1.1? Isn't it technically breaking? In my opinion this is really important and it'd be a shame if we'd had to wait for 4 more month.

[tkf]

Here is a quick monkey-patch you can do in ~/.julia/config/startup.jl to fix it (originally tkf/InteractiveCodeSearch.jl#3 (comment))

"""
Original `Base.find_source_file`.
"""
function _find_source_file_orig(path::AbstractString)
    (isabspath(path) || isfile(path)) && return path
    base_path = joinpath(Sys.BINDIR::String, Base.DATAROOTDIR, "julia", "base", path)
    return isfile(base_path) ? base_path : nothing
end

function Base.find_source_file(path::AbstractString)
    found = _find_source_file_orig(path)
    if found isa AbstractString && ! isfile(found)
        for m in methods(Pkg.add)
            exfile = try
                String(m.file)
            catch err
                continue
            end
            idx = findlast(joinpath(Base.Filesystem.path_separator,
                                    "share", "julia"), exfile)
            if idx isa Nothing
                continue
            end
            prefix = exfile[1:idx[1]]
            if startswith(path, prefix)
                # e.g., relpath = "share/julia/stdlib/v0.7/..."
                relpath = path[length(prefix)+1:end]
                return joinpath(Base.Sys.BINDIR, "..", relpath)
            end
        end
    end
    return found
end

[carstenbauer]

@tkf: This doesn't seem to work:

julia> using Statistics

julia> @which mean(rand(3))
mean(A::AbstractArray) in Statistics at C:\cygwin\home\Administrator\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.0\Statistics\src\Statistics.jl:128

[tkf]

It looks like which does not call find_source_file. My hack probably works only with @less and @edit. Also, not sure if it works in Windows.

[vtjnash]

Additional notes:

For LLDB, this can be corrected for by running settings set target.source-map /path/to/julia/build /path/to/julia/install. For macOS, this can be automated by creating a small text file with the content described at http://lldb.llvm.org/symbols.html. Otherwise, it would need to be put in a ~/.lldbinit file. On GDB, the equivalent command is set substitute-path /path/to/julia/build /path/to/julia/install and also may be automated by creating a ~/.gdbinit file or /usr/lib/debug/julia.gdb file.

[oschulz]

This still seems to be an issue (tried with v1.2-rc2 and v1.3, using the official binaries on 64-bit Linux). I guess this needs more than JuliaDebug/JuliaInterpreter.jl#144 and #31388 ?

Is there a chance to fix this in v1.2 or v1.3? It's possible to work around it (via symlink or so), I usually do, but that's kinda hard to sell that to novice users when introducing them to Julia (and showing them how easy it is to see how things work inside). :-)

[StefanKarpinski]

JuliaInterpreter/Debugger seems to have their own fix for this. Would either of @timholy or @KristofferC possibly know if that fix could be used on base itself?

[carstenbauer]

kinda hard to sell that to novice users when introducing them to Julia (and showing them how easy it is to see how things work inside)

+1 from me. The possibility to use @which and co. in front of a class to show them how easy it is to inspect Julia internals is typically a "wow" moment. I really hope this gets fixed soon!

[KristofferC]

We could probably use the same trick here. Will try it out and report back.