ElixirLS crashes due to "no function clause matching in ElixirLS.LanguageServer.Diagnostics.range/2"

[kaikuchn]

Environment

• Elixir & Erlang versions (elixir --version):

Erlang/OTP 24 [erts-12.2] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [jit]

Elixir 1.13.1 (compiled with Erlang/OTP 23)

• Elixir Language Server version: v0.10.0, ElixirLS compiled with Elixir 1.10.4 and erlang 22
• Operating system: Ubuntu 20.04.3 LTS (Focal Fossa)
• Editor or IDE name (e.g. Emacs/VSCode): VSCode
• Editor Plugin/LSP Client name and version: ElixirLS: Elixir support and debugger v0.10.0

Current behavior

ElixirLS crashes after(/during?) the Analyzing modules step.

[Info  - 11:33:43 AM] [ElixirLS Dialyzer] Analyzing 3061 modules: [REDACTED, ...]
[Info  - 11:35:24 AM] [ElixirLS Dialyzer] Analysis finished in 188539 milliseconds

11:35:25.790 [error] GenServer ElixirLS.LanguageServer.Server terminating
** (FunctionClauseError) no function clause matching in ElixirLS.LanguageServer.Diagnostics.range/2
    (language_server 0.10.0) lib/language_server/diagnostics.ex:256: ElixirLS.LanguageServer.Diagnostics.range(-1, %ElixirLS.LanguageServer.SourceFile{dirty?: false, text: "defmodule MyApp.MyWorker do\n  use MyApp.BackgroundWorker, queue: :my_queue\n\n  require Logger\n\n  def execute(_) do\n    # REDACTED_CODE  end\nend\n", version: 1})
    (language_server 0.10.0) lib/language_server/diagnostics.ex:208: anonymous fn/3 in ElixirLS.LanguageServer.Diagnostics.publish_file_diagnostics/3
    (elixir 1.13.1) lib/enum.ex:2396: Enum."-reduce/3-lists^foldl/2-0-"/3
    (language_server 0.10.0) lib/language_server/diagnostics.ex:190: ElixirLS.LanguageServer.Diagnostics.publish_file_diagnostics/3
    (language_server 0.10.0) lib/language_server/server.ex:1064: anonymous fn/4 in ElixirLS.LanguageServer.Server.publish_diagnostics/3
    (elixir 1.13.1) lib/enum.ex:2396: Enum."-reduce/3-lists^foldl/2-0-"/3
    (language_server 0.10.0) lib/language_server/server.ex:1061: ElixirLS.LanguageServer.Server.publish_diagnostics/3
    (language_server 0.10.0) lib/language_server/server.ex:1001: ElixirLS.LanguageServer.Server.handle_dialyzer_result/3
Last message: {:"$gen_cast", {:dialyzer_finished, [...REDACTED..., %Mix.Task.Compiler.Diagnostic{compiler_name: "ElixirLS Dialyzer", details: {:warn_behaviour, {'lib/my_app/background_worker.ex', -1, {MyApp.MyWorker, :perform, 1}}, {:callback_type_mismatch, [Oban.Worker, :perform, 1, '[any()]', '\'discard\' | \'ok\' | {\'discard\',_} | {\'error\',_} | {\'ok\',_} | {\'snooze\',pos_integer()}']}}, file: "/workspaces/MyApp/lib/my_app/my_worker.ex", message: "background_worker.ex:-1: The inferred return type of perform/1 \n         ([any()]) has nothing in common with \n          'discard' | 'ok' |\n          {'discard', _} |\n          {'error', _} |\n          {'ok', _} |\n          {'snooze', pos_integer()}, which is the expected return type for the callback of the 'Elixir.Oban.Worker' behaviour", position: -1, severity: :warning} ...REDACTED... (truncated)
[Info  - 11:35:31 AM] Connection to server got closed. Server will restart.
[Error - 11:35:31 AM] Request textDocument/codeLens failed.
Error: Connection got disposed.
	at Object.dispose (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-jsonrpc/lib/common/connection.js:1044:27)
	at Object.dispose (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-languageclient/lib/common/client.js:73:35)
	at LanguageClient.handleConnectionClosed (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-languageclient/lib/common/client.js:2424:42)
	at LanguageClient.handleConnectionClosed (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-languageclient/lib/node/main.js:155:15)
	at closeHandler (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-languageclient/lib/common/client.js:2411:18)
	at CallbackList.invoke (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-jsonrpc/lib/common/events.js:55:39)
	at Emitter.fire (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-jsonrpc/lib/common/events.js:117:36)
	at closeHandler (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-jsonrpc/lib/common/connection.js:256:26)
	at CallbackList.invoke (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-jsonrpc/lib/common/events.js:55:39)
	at Emitter.fire (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-jsonrpc/lib/common/events.js:117:36)
	at StreamMessageReader.fireClose (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-jsonrpc/lib/common/messageReader.js:40:27)
	at Socket.<anonymous> (/home/gitpod/.vscode-remote/extensions/jakebecker.elixir-ls-0.10.0/node_modules/vscode-jsonrpc/lib/common/messageReader.js:125:42)
	at Socket.emit (node:events:402:35)
	at Pipe.<anonymous> (node:net:687:12)

Expected behavior

ElixirLS Dialyzer (? not sure who exactly) should not generate diagnostic output with a negative position and thus not crash the GenServer.
Here the spec says that the position should be always positive. However, the docs at the same time contradict this by saying that 0 represents unknown. That's also what's been implemented: the code for ElixirLS.LanguageServer.Diagnostics.range/2 deals with 0 as a special case, i.e., it can handle any non-negative integer positions.

[lukaszsamson]

Can you post a project that reproduces this error?

[kaikuchn]

I tried to create a minimal project that reproduces the error. But I can't reproduce it. :/
Sadly I also cannot share the project where I'm encountering the issue.

How can I try to find out why/who created the diagnostics with a negative position? Is there some option to enable tracing?

[barttenbrinke]

I have the same issue since yesterday on an unsharable project - it is an older style Elixir Umbrella app. Is there any info we can provide to help? BTW This project is awesome :D

[barttenbrinke]

Could it be a version mismatch issue between ElixirLS and the project?

Elixir version: "1.10.3 (compiled with Erlang/OTP 21)"
Erlang version: "23"
ElixirLS compiled with Elixir 1.10.4 and erlang 22

cat .tool-versions
elixir 1.10.3
erlang 23.2.6

Erlang 22 vs 23 and 24 for the topic starter.

Btw, my diagnostic range is nil:

ElixirLS.LanguageServer.Diagnostics.range(nil, 

[lukaszsamson]

You can build elixirLS from source and inspect the diagnostics returned by dialyzer in

elixir-ls/apps/language_server/lib/language_server/dialyzer.ex

Line 111 in 911688b

diagnostics = to_diagnostics(warnings, state.warn_opts, state.warning_format)

and elixir compiler in

elixir-ls/apps/language_server/lib/language_server/build.ex

Line 80 in 911688b

case Kernel.ParallelCompiler.compile([mixfile]) do

and

elixir-ls/apps/language_server/lib/language_server/build.ex

Line 139 in 911688b

case Mix.Task.run("compile", ["--return-errors", "--ignore-module-conflict"]) do

My suspicion is one of them is returning invalid data (both should never return negative values)

The other possible source of this error is

elixir-ls/apps/language_server/lib/language_server/diagnostics.ex

Line 13 in 911688b

|> maybe_update_position(type, line, stacktrace)

- we do some normalization that may by broken

[barttenbrinke]

Thanks @lukaszsamson . Awesome work 👍