Simplest CompletionItem removes all leading whitespace

[rcjsuen]

Reproduced in 0.12.0 and 0.13.0-20250424-115448.

1. Use a language server that returns the simplest CompletionItem with just label defined.
2. Put some whitespace in front before invoking code completion.
3. Accept the item.
4. All leading whitespace is deleted.

{
  "isIncomplete": false,
  "items": [
    {
      "label": "driver"
    }
  ]
}

2025-04-25-simple-code-completion-label-bug.mov

[angelozerr]

@rcjsuen could you please share your full LSP trace with didOpen, completion, etc

It will help me to write tests.

[rcjsuen]

@angelozerr Does this help?

[Trace - 09:01:54] Sending request 'initialize - (1)'.
Params: {
  "processId": 4411,
  "rootPath": "tmp",
  "rootUri": "file://tmp",
  "initializationOptions": {},
  "capabilities": {
    "workspace": {
      "applyEdit": true,
      "workspaceEdit": {
        "documentChanges": true,
        "resourceOperations": [
          "create",
          "delete",
          "rename"
        ]
      },
      "didChangeConfiguration": {
        "dynamicRegistration": true
      },
      "didChangeWatchedFiles": {
        "dynamicRegistration": true
      },
      "symbol": {},
      "executeCommand": {
        "dynamicRegistration": true
      },
      "workspaceFolders": true,
      "configuration": true,
      "semanticTokens": {
        "refreshSupport": true
      },
      "codeLens": {
        "refreshSupport": true
      },
      "fileOperations": {
        "didRename": true,
        "willRename": true,
        "dynamicRegistration": true
      },
      "inlayHint": {
        "refreshSupport": true
      }
    },
    "textDocument": {
      "synchronization": {
        "willSave": true,
        "willSaveWaitUntil": true,
        "didSave": true
      },
      "completion": {
        "completionItem": {
          "snippetSupport": true,
          "documentationFormat": [
            "markdown",
            "plaintext"
          ],
          "deprecatedSupport": true,
          "resolveSupport": {
            "properties": [
              "documentation",
              "detail",
              "additionalTextEdits"
            ]
          },
          "insertTextModeSupport": {
            "valueSet": [
              1,
              2
            ]
          },
          "labelDetailsSupport": true
        },
        "completionList": {
          "itemDefaults": [
            "editRange"
          ]
        },
        "dynamicRegistration": true
      },
      "hover": {
        "contentFormat": [
          "markdown",
          "plaintext"
        ],
        "dynamicRegistration": true
      },
      "signatureHelp": {
        "signatureInformation": {
          "parameterInformation": {
            "labelOffsetSupport": true
          }
        },
        "dynamicRegistration": true
      },
      "references": {
        "dynamicRegistration": true
      },
      "documentHighlight": {
        "dynamicRegistration": true
      },
      "documentSymbol": {
        "symbolKind": {
          "valueSet": [
            18,
            17,
            5,
            14,
            9,
            10,
            22,
            24,
            8,
            1,
            12,
            11,
            20,
            6,
            2,
            3,
            21,
            16,
            19,
            25,
            4,
            7,
            15,
            23,
            26,
            13
          ]
        },
        "hierarchicalDocumentSymbolSupport": true,
        "dynamicRegistration": true
      },
      "formatting": {
        "dynamicRegistration": true
      },
      "rangeFormatting": {
        "dynamicRegistration": true
      },
      "declaration": {
        "linkSupport": true,
        "dynamicRegistration": true
      },
      "definition": {
        "linkSupport": true,
        "dynamicRegistration": true
      },
      "typeDefinition": {
        "linkSupport": true,
        "dynamicRegistration": true
      },
      "implementation": {
        "linkSupport": true,
        "dynamicRegistration": true
      },
      "codeAction": {
        "codeActionLiteralSupport": {
          "codeActionKind": {
            "valueSet": [
              "quickfix",
              "refactor",
              "refactor.extract",
              "refactor.inline",
              "refactor.rewrite",
              "source",
              "source.organizeImports"
            ]
          }
        },
        "dataSupport": true,
        "resolveSupport": {
          "properties": [
            "edit"
          ]
        },
        "dynamicRegistration": true
      },
      "codeLens": {
        "dynamicRegistration": true
      },
      "documentLink": {
        "dynamicRegistration": true
      },
      "colorProvider": {
        "dynamicRegistration": true
      },
      "rename": {
        "prepareSupport": true,
        "dynamicRegistration": true
      },
      "publishDiagnostics": {
        "relatedInformation": true,
        "tagSupport": {
          "valueSet": [
            1,
            2
          ]
        },
        "codeDescriptionSupport": true,
        "dataSupport": true
      },
      "foldingRange": {
        "dynamicRegistration": true
      },
      "typeHierarchy": {
        "dynamicRegistration": true
      },
      "callHierarchy": {
        "dynamicRegistration": true
      },
      "semanticTokens": {
        "requests": {
          "range": false,
          "full": true
        },
        "tokenTypes": [
          "namespace",
          "type",
          "class",
          "enum",
          "interface",
          "struct",
          "typeParameter",
          "parameter",
          "variable",
          "property",
          "enumMember",
          "event",
          "function",
          "method",
          "macro",
          "keyword",
          "modifier",
          "comment",
          "string",
          "number",
          "regexp",
          "operator",
          "decorator",
          "label"
        ],
        "tokenModifiers": [
          "declaration",
          "definition",
          "readonly",
          "static"
        ],
        "formats": [
          "relative"
        ],
        "multilineTokenSupport": true,
        "serverCancelSupport": true,
        "dynamicRegistration": true
      },
      "inlayHint": {
        "dynamicRegistration": true
      },
      "diagnostic": {
        "relatedDocumentSupport": true,
        "dynamicRegistration": true
      }
    },
    "window": {
      "workDoneProgress": true,
      "showMessage": {},
      "showDocument": {
        "support": true
      }
    },
    "general": {
      "staleRequestSupport": {
        "cancel": true,
        "retryOnContentModified": []
      },
      "positionEncodings": [
        "utf-16"
      ]
    }
  },
  "clientInfo": {
    "name": "GoLand 2024.1.6",
    "version": "GoLand (build GO-241.19072.18)"
  },
  "trace": "off",
  "workspaceFolders": [
    {
      "uri": "file://tmp",
      "name": "docker-language-server"
    }
  ]
}


[Trace - 09:01:54] Sending notification 'initialized'
Params: {}


[Trace - 09:01:54] Received response 'initialize - (1)' in 14ms.
Result: {
  "capabilities": {
    "textDocumentSync": {
      "openClose": true,
      "change": 1
    },
    "hoverProvider": {},
    "completionProvider": {},
    "definitionProvider": {},
    "documentHighlightProvider": {},
    "documentSymbolProvider": {},
    "codeActionProvider": {},
    "documentLinkProvider": {},
    "executeCommandProvider": {
      "commands": [
        "dockerLspServer.telemetry.callback"
      ]
    },
    "semanticTokensProvider": {
      "legend": {
        "tokenTypes": [
          "type",
          "class",
          "string",
          "variable",
          "property",
          "keyword",
          "operator",
          "number",
          "comment"
        ],
        "tokenModifiers": []
      },
      "range": false,
      "full": true
    },
    "inlayHintProvider": {}
  },
  "serverInfo": {
    "name": "docker-language-server",
    "version": "2025-04-22-0b07900"
  }
}


[Trace - 09:01:54] Sending notification 'textDocument/didOpen'
Params: {
  "textDocument": {
    "uri": "file://tmp/docker-compose.yml",
    "languageId": "dockercompose",
    "version": 1,
    "text": "configs:\n  testConfig:\n    "
  }
}


[Trace - 09:01:59] Sending request 'textDocument/completion - (5)'.
Params: {
  "context": {
    "triggerKind": 1
  },
  "textDocument": {
    "uri": "file://tmp/docker-compose.yml"
  },
  "position": {
    "line": 2,
    "character": 4
  }
}


[Trace - 09:01:59] Received response 'textDocument/completion - (5)' in 1ms.
Result: {
  "isIncomplete": false,
  "items": [
    {
      "label": "content"
    },
    {
      "label": "environment"
    },
    {
      "label": "external"
    },
    {
      "label": "file"
    },
    {
      "label": "labels"
    },
    {
      "label": "name"
    },
    {
      "label": "template_driver"
    }
  ]
}


[Trace - 09:02:00] Sending notification 'textDocument/didChange'
Params: {
  "textDocument": {
    "version": 2,
    "uri": "file://tmp/docker-compose.yml"
  },
  "contentChanges": [
    {
      "text": "configs:\n  testConfig:\ncontent"
    }
  ]
}

[angelozerr]

Yes it is perfect, thanks

[angelozerr]

Managing completion without text range is not trivial, because LSP4IJ must compute the proper text range to replace.

In your usecase, LSP4IJ use the YamlPsiElement text range to know which range must be replaced. It is the explanation of this behaviour.

[rcjsuen]

Managing completion without text range is not trivial, because LSP4IJ must compute the proper text range to replace.

In your usecase, LSP4IJ use the YamlPsiElement text range to know which range must be replaced. It is the explanation of this behaviour.

I see. It can't just use "replace nothing" and add text where the text cursor is at?

[angelozerr]

The best thing is to generate completion with textedit which declare range

[rcjsuen]

The best thing is to generate completion with textedit which declare range

I take your point and I was planning to go down this path anyway as it provides better control (instead of relying on the client's behaviour) but the fact remains that this is valid by the specification.

[angelozerr]

I agree that it is valid by the specification.

vscode uses the textmate tokenizers to manage correctly the replace to do.

LSP4IJ uses the PsiFile tokenizers to do this replace. The only solution that I see for your usecase is to avoid using this PsiFile. To do that we could provide a client settings to avoid using PsiFile info when replace must occurs when completion item doesnt provide textedit
.

[rcjsuen]

Thanks for the added context.

While this is a deal breaker for me right now it will not be after I switch to using a textEdit. I understand that this is likely a very low priority issue (given that no one else has raised this in the past) and can't imagine this being easy to fix given what you have just shared.

Thanks for taking a look at this, Angelo.

[sergeysavchuk]

@angelozerr I've reproduced the issue in my projects too, maybe do you have some updates, ETAs. thanks

[angelozerr]

With YAML file? I suppose that your language server doesn't take care of textedit when completion is applied, right?

[sergeysavchuk]

@angelozerr no, with my custom file.

I have the following case:

Steps to reproduce:

1. Type a keyword
2. Add a new line and several whitespaces after the keyword
3. Trigger completion using a hotkey (not by typing a character):

textDocument/completion
Position [
  line = 1
  character = 3
]

And when I select the completion item (e.g., insertText = "@Test"), the completion text is inserted correctly, but all whitespaces and newlines between the original keyword and the new text are removed.
And client send didChange without whitespaces to the server.

[angelozerr]

When you apply completion from a language server result. There is 2 usecases:

• 1. your language server returns text edit with the range to replace. It will work like any IDE/Editors (vscode, LSP4IJ, etc). I suggest really that your language server supports that.
• 2. your language server returns just text to insert (without range). With LSP4IJ there are 2 usecases:
  • 2.a) the PsiFile to update doesn't manage proper PsiElement (ex: TEXT, TextMate language), in this case LSP4IJ tries to get word to replace (with a generic mean)
  • 2b) the PsiFile to update manages PsiElement, LSP4IJ uses the text range of the PsiElement to know which content must be replaced.

The original issue is 2b) which uses an empty YAML PsiElement which covers all spaces which are replaced.

I presume that you are also in 2) usecase.

I suggest really that your language server supports textedit with completion.

And client send didChange without whitespaces to the server.

You mean that editor content will be unsynchronized with teh document of the language server ? If yes it is very annoying.