Crash

[benkeil]

Environment

Erlang/OTP 24 [erts-12.0.3] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit] [dtrace]

Elixir 1.12.2 (compiled with Erlang/OTP 24)

• Operating system: macOS Big Sur 11.4 (20F71)
• Editor or IDE name VSCode: Version: 1.58.0
• Editor Plugin/LSP Client name: https://github.com/elixir-lsp/vscode-elixir-ls

Logs

[Error - 08:32:56] Request textDocument/completion failed.
  Message: an exception was raised:
    ** (FunctionClauseError) no function clause matching in String.slice/2
        (elixir 1.12.2) lib/string.ex:2086: String.slice("String.", %Inspect.Error{message: "got FunctionClauseError with message \"no function clause matching in Inspect.Range.inspect/2\" while inspecting %{__struct__: Range, first: 0, last: -2}"})
        (elixir_sense 2.0.0) lib/elixir_sense/core/source.ex:44: ElixirSense.Core.Source.split_module_and_hint/3
        (elixir_sense 2.0.0) lib/elixir_sense/providers/suggestion/reducers/type_specs.ex:43: ElixirSense.Providers.Suggestion.Reducers.TypeSpecs.add_types/5
        (elixir 1.12.2) lib/enum.ex:4280: Enumerable.List.reduce/3
        (elixir 1.12.2) lib/enum.ex:2431: Enum.reduce_while/3
        (elixir_sense 2.0.0) lib/elixir_sense/providers/suggestion.ex:112: ElixirSense.Providers.Suggestion.find/4
        (language_server 0.7.0) lib/language_server/providers/completion.ex:137: ElixirLS.LanguageServer.Providers.Completion.completion/4
        (language_server 0.7.0) lib/language_server/server.ex:770: anonymous fn/3 in ElixirLS.LanguageServer.Server.handle_request_async/2
  Code: -32000 

Reproduce

The code is from the elixir guide. When open autocomplete after String. in String.t()it crashes.

defmodule LousyCalculator do
  @typedoc """
  Just a number followed by a string.
  """
  @type number_with_remark :: {number, String.t()}

  @spec add(number, number) :: number_with_remark
  def add(x, y), do: {x + y, "You need a calculator to do that?"}

  @spec multiply(number, number) :: number_with_remark
  def multiply(x, y), do: {x * y, "It is like addition on steroids."}
end

[lukaszsamson]

@benkeil please post a project or a snippet that reproduces this crash.

[benkeil]

There is a big snippet…

[lukaszsamson]

It looks like a regression in elixir standard library. I can reproduce it with elixir-ls compiled with elixir < 1.12 and run on 1.12. When I compile and run on 1.12 the error no longer happens.

[lukaszsamson]

The relevant fixes will be included in elixir >= 1.12.3. Consider upgrading to 1.12.3 when it's released or downgrading to 1.11.x. Theoretically we could workaround the issue by avoiding all elixir APIs using Range but IMO it's not worth the cost as it would touch elixir-ls and all its deps. This is another case whre our packaging approach is not optimal. See #115 for more details.