Rubocop warnings with zero length do not show up in editor

[trkoch]

Your environment

• vscode-ruby version: 0.22.3
• Ruby version: 2.6 (also tested with 2.5)
• Ruby version manager (if any): rbenv
• VS Code version: 1.33.0 (also tested with previous version)
• Operating System: macOS
• Using language server? Yes (cannot reproduce without language server)

Expected behavior

Extension reports all warnings detected by rubocop as problems and decorates significant characters.

Actual behavior

I'm having the issue that some warnings reported by rubocop (when run manually) do not show up in the editor (0 problems, no decorations). I noticed this applies to errors where start_column/last_column in JSON output of rubocop are identical.

Hints

vscode-ruby/server/src/linters/RuboCop.ts

Lines 87 to 95 in 2d8e443

	range: {
	start: {
	line: offense.location.line - 1,
	character: offenseCharacter,
	},
	end: {
	line: offense.location.line - 1,
	character: offenseCharacter + offense.location.length - 1,
	},

Are you sure it's required to subtract from offense.location.length? Removing the subtraction appears to fix this error and also a glitch where the last character of an error is not decorated.

[wingrunr21]

I'm sure it is required as VSCode uses a 0 offset while RuboCop uses a 1 offset.

Do you have an example file I can use?

[trkoch]

Is this true for both lines and columns?

Example

$ cat some_controller.rb

# frozen_string_literal: true

class SomeController < ApplicationController
  def show
    @record = Record.find(params[:id])
  # end
end

$ rubocop some_controller.rb -f json

{
  "metadata": {
    "rubocop_version": "0.65.0",
    "ruby_engine": "ruby",
    "ruby_version": "2.6.2",
    "ruby_patchlevel": "47",
    "ruby_platform": "x86_64-darwin18"
  },
  "files": [
    {
      "path": "some_controller.rb",
      "offenses": [
        {
          "severity": "error",
          "message": "Lint/Syntax: unexpected token $end\n(Using Ruby 2.6 parser; configure using `TargetRubyVersion` parameter, under `AllCops`)",
          "cop_name": "Lint/Syntax",
          "corrected": false,
          "location": {
            "start_line": 8,
            "start_column": 1,
            "last_line": 8,
            "last_column": 0,
            "length": 0,
            "line": 8,
            "column": 1
          }
        }
      ]
    }
  ],
  "summary": {
    "offense_count": 1,
    "target_file_count": 1,
    "inspected_file_count": 1
  }
}

diff --git a/server/src/linters/RuboCop.ts b/server/src/linters/RuboCop.ts
index 2bc01c4..df27c20 100644
--- a/server/src/linters/RuboCop.ts
+++ b/server/src/linters/RuboCop.ts
@@ -71,6 +71,7 @@ export default class RuboCop extends BaseLinter {
                        const offenses: IRuboCopResults = JSON.parse(data);

                        for (const file of offenses.files) {
+                               file.offenses.forEach(o => console.log(this.rubocopOffenseToDiagnostic(o)));
                                const diagnostics = file.offenses.map(o => this.rubocopOffenseToDiagnostic(o));
                                results = results.concat(diagnostics);
                        }

Current behavior

Ruby Language Server (Output)

Lint: executing rubocop -s /Users/tristan/Desktop/project/some_controller.rb -f json --force-exclusion...
{ range:
   { start: { line: 7, character: 0 },
     end: { line: 7, character: -1 } },
  severity: 1,
  message:
   'Lint/Syntax: unexpected token $end\n(Using Ruby 2.6 parser; configure using `TargetRubyVersion` parameter, under `AllCops`)',
  source: 'Lint/Syntax',
  code: 'RuboCop' }

Note -1 in range.end.character.

Proposed changes

diff --git a/server/src/linters/RuboCop.ts b/server/src/linters/RuboCop.ts
index 2bc01c4..df27c20 100644
--- a/server/src/linters/RuboCop.ts
+++ b/server/src/linters/RuboCop.ts
@@ -91,7 +92,7 @@ export default class RuboCop extends BaseLinter {
                                },
                                end: {
                                        line: offense.location.line - 1,
-                                       character: offenseCharacter + offense.location.length - 1,
+                                       character: offenseCharacter + offense.location.length,
                                },
                        },
                        severity: this.DIAGNOSTIC_SEVERITIES[offense.severity],

Ruby Language Server (Output)

Lint: executing rubocop -s /Users/tristan/Desktop/project/some_controller.rb -f json --force-exclusion...
{ range:
   { start: { line: 7, character: 0 },
     end: { line: 7, character: 0 } },
  severity: 1,
  message:
   'Lint/Syntax: unexpected token $end\n(Using Ruby 2.6 parser; configure using `TargetRubyVersion` parameter, under `AllCops`)',
  source: 'Lint/Syntax',
  code: 'RuboCop' }

Note 0 in range.end.character.

1 Problem

[wingrunr21]

yes it is true. You aren't taking into account that RuboCop is outputting an end position before the start position for this particular error. That's why it appears to "work" when you remove the subtraction.

[trkoch]

Building on the previous example, another example…

This time VSCode correctly indicates a warning, but fails to correctly highlight its boundaries.

Current behavior

Proposed changes

[wingrunr21]

def foo
end

Does that give you an EmptyMethod warning with the whole def line underlined? I don't think this is as straightforward as you think it is

[trkoch]

Yes. Interestingly with both current behavior and proposed changes.

{
  "metadata": {
    "rubocop_version": "0.65.0",
    "ruby_engine": "ruby",
    "ruby_version": "2.6.2",
    "ruby_patchlevel": "47",
    "ruby_platform": "x86_64-darwin18"
  },
  "files": [
    {
      "path": "some_controller.rb",
      "offenses": [
        {
          "severity": "warning",
          "message": "Lint/UselessAssignment: Useless assignment to variable - `unused`.",
          "cop_name": "Lint/UselessAssignment",
          "corrected": false,
          "location": {
            "start_line": 9,
            "start_column": 5,
            "last_line": 9,
            "last_column": 10,
            "length": 6,
            "line": 9,
            "column": 5
          }
        },
        {
          "severity": "convention",
          "message": "Style/EmptyMethod: Put empty method definitions on a single line.",
          "cop_name": "Style/EmptyMethod",
          "corrected": false,
          "location": {
            "start_line": 12,
            "start_column": 3,
            "last_line": 13,
            "last_column": 5,
            "length": 13,
            "line": 12,
            "column": 3
          }
        }
      ]
    }
  ],
  "summary": {
    "offense_count": 2,
    "target_file_count": 1,
    "inspected_file_count": 1
  }
}

Current behavior

Proposed changes

I agree it's probably not as straightforward as I think. Thanks for taking a closer look!

[trkoch]

Attempting to avoid any misconceptions, main issue being here that VSCode does not detect some errors at all (apparently those with range.end.character = -1).

[wingrunr21]

I think there's two things that need fixed here:

1. Things with length 0 need to have their start/ends set to the error row but a column of either start or end. For the Parser error, I'm not sure what's going to make more sense to display that on the line. It may be that we need to actually set that as the whole line
2. Sometimes the RuboCop error does not encompass the whole warning (I just reproduced this as well). That seems to indicate the translation between what RuboCop outputs and the VSCode file mapping is inconsistent.

[trkoch]

Any news? Can I help?

[wingrunr21]

I'm troubleshooting a variety of RuboCop related errors. This will be looked at but there are A) more pressing bugs and B) I have limited time right now to spend on this. In addition, I'm trying to get a test suite/harness set up to allow easier community contribution. It'll get done but I've got a full time job + other life obligations.

[minkir014]

See this extension. It doesn't run into the issues here maybe you could compare your code to its code.
https://github.com/misogi/vscode-ruby-rubocop

[trkoch]

@wingrunr21 Sorry, I did not mean to put you under pressure. Thank you for your effort!

[andrewmcodes]

Just want to add I’m also seeing this issue on a ruby 2.6.3 project. Tried a few things anencephaly have been looking into the code and will update with a solution or PR if I find the problem.