Unicode entering mode within square brackets broken

[Jutho]

Within square brackets that follow a variable (i.e. a getindex operation), tab completion for entering Unicode is broken, unless the variable in front is a Dict or an Array. I tried to trace down the error in REPLCompletetions.

I think the problem is that dict_identifier_key returns (true,nothing,nothing) for any variable (which is not a dict), such that the function completions returns early with this line:
https://github.com/JuliaLang/julia/blob/master/base/repl/REPLCompletions.jl#L493

The only exception are Arrays, since they are special cased in dict_identifier_key to return (nothing,nothing,nothing) in line
https://github.com/JuliaLang/julia/blob/master/base/repl/REPLCompletions.jl#L459

Is it my understanding that something is wrong here. I don't know much about the whole REPL module, but the name dict_identifier_key seems to suggest that it should only pick out Dicts, and should therefore return (nothing,nothing,nothing) for anything that is not a Dict.

[Jutho]

Also, minimal example:

a=randn(2,2);
f=qrfact(a)
a[\+TAB]  #=> all possible Unicode completions
f[\+TAB] #=> nothing

[Jutho]

If somebody could give some pointers as to the correct fix, I could try to prepare a PR.

[IlyaOrson]

I also found this recently:

# X is undefined
X["\Delta<TAB>"] # X["Δ"]
X["\Delta<TAB><TAB>"] # X["Δ"]

X = Dict("Δ" => 1)
X["\Delta<TAB>"] # X["Δ"]
X["\Delta<TAB><TAB>"] # UnicodeError

X = 1
X["\Delta<TAB>"] # no completion

[CarloLucibello]

actually for me on 1.0.1 general completion within indexing is broken, e.g.:

jualia> using DataFrames

julia> df = DataFrame(ciao=rand(3))
3×1 DataFrame
│ Row │ ciao      │
│     │ Float64   │
├─────┼───────────┤
│ 1   │ 0.175749  │
│ 2   │ 0.0407557 │
│ 3   │ 0.0945494 │

julia> df[df.ci<Tab>            # NOT COMPLETING