using - give a hint in error message when there is a typo in package name

[strickek]

I think it is a very common mistake with using statements. As package names are case-sensitive, a small typo in name, eg DataFrames: Dataframes, DataFrame, Dataframe, ..., results in an error message:

julia> using Dataframes
ERROR: ArgumentError: Package Dataframes not found in current path:

• Run import Pkg; Pkg.add("Dataframes") to install the Dataframes package.

Stacktrace:
[1] require(into::Module, mod::Symbol)
@ Base ./loading.jl:874

in the next step the user will do the suggested solution, which will not work:

julia> import Pkg; Pkg.add("Dataframes")
Updating registry at ~/.julia/registries/General
ERROR: The following package names could not be resolved:

• Dataframes (not found in project, manifest or registry)

Stacktrace:
[1] pkgerror(msg::String)
@ Pkg.Types ~/projects/julia/usr/share/julia/stdlib/v1.6/Pkg/src/Types.jl:52
[2] ensure_resolved(ctx::Pkg.Types.Context, pkgs::Vector{Pkg.Types.PackageSpec}; registry::Bool)
@ Pkg.Types ~/projects/julia/usr/share/julia/stdlib/v1.6/Pkg/src/Types.jl:823
...

I suggest to offer a different error message if there is an installed package with an similar name (in Stdlib or in Project deps), like:

julia> using Dataframes
ERROR: ArgumentError: Did you mean DataFrames? Your entry Dataframes is
not found in current path. Correct your entry and try again, or run
import Pkg; Pkg.add("Dataframes") to install the Dataframes package.

Stacktrace:
[1] require(into::Module, mod::Symbol)
@ Base ./loading.jl:868

If this is ok, I can offer to open a pull request (have already a first draft).

[KristofferC]

Either, we allow Pkg to install a hook into the error message or we implement the registry parsing ourselves in Base.

[vtjnash]

Pkg does install a hook (via REPL), which seems like it could do this?