textDocumentSync coming back as 0/None

[tom-bowles]

When using OmniSharp LSP from emacs lsp-mode, the initialize handshake is as shown at the bottom. The server response contains "textDocumentSync": 0, so lsp-mode sends no textDocument/didChange notifications.

The relevant code in LanguageServer.cs is also shown below. The check for ccp.HasStaticHandler(textDocumentCapabilities.Synchronization) returns false because although there is a TextDocumentSyncHandler registered (specifically OmnisharpTextDocumentSyncHandler), TextDocumentSyncHandler doesn't provide IWillSaveTextDocumentHandler or IWillSaveWaitUntilTextDocumentHandler, both of which are linked to SynchronizationCapability.

Removing the check causes the server to return a textDocumentSync options block, but the change item is set to 1 (full) rather than 2 (incremental). This appears to be because there are two OmnisharpTextDocumentSyncHandlers registered, one for cake and one for cs/csx, and the cake one doesn't handle incremental. Not sure if that should be a separate issue for omnisharp-roslyn, but it means you can't send incremental changes for cs/csx files because the Min() call in the code below means it picks up kind 1.

            if (ccp.HasStaticHandler(textDocumentCapabilities.Synchronization))
            {
                var textDocumentSyncKind = _collection.ContainsHandler(typeof(IDidChangeTextDocumentHandler))
                    ? _collection
                        .Select(x => x.Handler)
                        .OfType<IDidChangeTextDocumentHandler>()
                        .Where(x => x.GetRegistrationOptions()?.SyncKind != TextDocumentSyncKind.None)
                        .Min(z => z.GetRegistrationOptions()?.SyncKind)
                    : TextDocumentSyncKind.None;

                if (_clientVersion == ClientVersion.Lsp2)
                {
                    serverCapabilities.TextDocumentSync = textDocumentSyncKind;
                }
                else
                {
                    serverCapabilities.TextDocumentSync = new TextDocumentSyncOptions()
                    {
                        Change = textDocumentSyncKind ?? TextDocumentSyncKind.None,
                        OpenClose = _collection.ContainsHandler(typeof(IDidOpenTextDocumentHandler)) || _collection.ContainsHandler(typeof(IDidCloseTextDocumentHandler)),
                        Save = _collection.ContainsHandler(typeof(IDidSaveTextDocumentHandler)) ?
                            new SaveOptions() { IncludeText = true /* TODO: Make configurable */ } :
                            null,
                        WillSave = _collection.ContainsHandler(typeof(IWillSaveTextDocumentHandler)),
                        WillSaveWaitUntil = _collection.ContainsHandler(typeof(IWillSaveWaitUntilTextDocumentHandler))
                    };
                }
            }

[Trace - 12:19:49 PM] Sending request 'initialize - (55)'.
Params: {
  "processId": 33868,
  "rootPath": "p:/experiments/LspTest/",
  "rootUri": "file:///p:/experiments/LspTest/",
  "capabilities": {
    "workspace": {
      "workspaceEdit": {
        "documentChanges": true,
        "resourceOperations": [
          "create",
          "rename",
          "delete"
        ]
      },
      "applyEdit": true,
      "symbol": {
        "symbolKind": {
          "valueSet": [
            1,
            2,
            3,
            4,
            5,
            6,
            7,
            8,
            9,
            10,
            11,
            12,
            13,
            14,
            15,
            16,
            17,
            18,
            19,
            20,
            21,
            22,
            23,
            24,
            25,
            26
          ]
        }
      },
      "executeCommand": {
        "dynamicRegistration": false
      },
      "didChangeWatchedFiles": {
        "dynamicRegistration": true
      },
      "workspaceFolders": true,
      "configuration": true
    },
    "textDocument": {
      "declaration": {
        "linkSupport": true
      },
      "definition": {
        "linkSupport": true
      },
      "implementation": {
        "linkSupport": true
      },
      "typeDefinition": {
        "linkSupport": true
      },
      "synchronization": {
        "didSave": true,
        "willSaveWaitUntil": true
      },
      "documentSymbol": {
        "symbolKind": {
          "valueSet": [
            1,
            2,
            3,
            4,
            5,
            6,
            7,
            8,
            9,
            10,
            11,
            12,
            13,
            14,
            15,
            16,
            17,
            18,
            19,
            20,
            21,
            22,
            23,
            24,
            25,
            26
          ]
        },
        "hierarchicalDocumentSymbolSupport": true
      },
      "formatting": {
        "dynamicRegistration": true
      },
      "codeAction": {
        "dynamicRegistration": true,
        "codeActionLiteralSupport": {
          "codeActionKind": {
            "valueSet": [
              "",
              "quickfix",
              "refactor",
              "refactor.extract",
              "refactor.inline",
              "refactor.rewrite",
              "source",
              "source.organizeImports"
            ]
          }
        }
      },
      "completion": {
        "completionItem": {
          "snippetSupport": true,
          "documentationFormat": [
            "markdown"
          ]
        },
        "contextSupport": true
      },
      "signatureHelp": {
        "signatureInformation": {
          "parameterInformation": {
            "labelOffsetSupport": true
          }
        }
      },
      "documentLink": {
        "dynamicRegistration": true
      },
      "hover": {
        "contentFormat": [
          "markdown",
          "plaintext"
        ]
      },
      "foldingRange": {
        "dynamicRegistration": true,
        "rangeLimit": null,
        "lineFoldingOnly": false
      }
    }
  },
  "initializationOptions": null
}


[Trace - 12:20:01 PM] Received response 'initialize - (55)' in 753ms.
Result: {
  "capabilities": {
    "experimental": {
    },
    "renameProvider": {
      "prepareProvider": null
    },
    "documentOnTypeFormattingProvider": {
      "moreTriggerCharacter": [
        "}",
        ")"
      ],
      "firstTriggerCharacter": ";"
    },
    "documentRangeFormattingProvider": true,
    "documentFormattingProvider": null,
    "codeLensProvider": {
      "resolveProvider": true
    },
    "workspaceSymbolProvider": null,
    "documentSymbolProvider": true,
    "documentHighlightProvider": null,
    "referencesProvider": true,
    "definitionProvider": true,
    "signatureHelpProvider": {
      "triggerCharacters": [
        ".",
        "?",
        "["
      ]
    },
    "completionProvider": {
      "triggerCharacters": [
        "."
      ],
      "resolveProvider": null
    },
    "hoverProvider": true,
    "textDocumentSync": 0
  }
}

[david-driscoll]

@tom-bowles sounds like there are two issues.

Issue 1

ccp.HasStaticHandler(textDocumentCapabilities.Synchronization) returns false if IWillSaveTextDocumentHandler or IWillSaveWaitUntilTextDocumentHandler are not implemented. That sounds a bug and I'll take a look at what might be causing it. If dynamic registration is supported for Synchronization then this will always return false (that's intended). Looking at the code it seems like this is a bug, that we'll look to fix.

Issue 2

Currently cake doesn't support incremental changes, so we only have one choice we can make, which is to force full text changes, this is because the InitializeResult does not define the ability to define more than one text change strategy. You have to pick one, and only one, so we pick the least specific one. It's easier to support full text change than it is incremental for all handlers.

Now the complication comes in when the client supports Dynamic Registration. If dynamic registration is supported, then we return TextDocumentSyncKind.None specifically because after initialize we turn around an register the handler specifically with it's defined TextDocumentSyncKind. When dynamic registration is not defined we again have to pick the least common denominator, so if there are any providers that take in TextDocumentSyncKind.Full we must fulfill that specification.

[david-driscoll]

For the first issue, I've simply changed the implementation to look for Any vs All, this fixes this return value issue.

For the second issue with the first fixed, if synchronization is not dynamic, it should fall into the correct code path and return the proper values.

see #163

[tom-bowles]

Wow, awesomely quick - thanks! I'll give this a try in the morning.

[david-driscoll]

Well keep in mind we still have to update OmniSharp roslyn and stuff, unless you have a fork locally for your testing.

[tom-bowles]

I do! However, I get:

System.InvalidOperationException: Sequence contains no elements
   at System.Linq.Enumerable.Min[TSource](IEnumerable`1 source)
   at OmniSharp.Extensions.LanguageServer.Protocol.Server.Capabilities.TextDocumentSyncOptions.Of(IEnumerable`1 options)
   at OmniSharp.Extensions.LanguageServer.Server.LanguageServer.<OmniSharp-Extensions-Embedded-MediatR-IRequestHandler<OmniSharp-Extensions-LanguageServer-Protocol-Models-InitializeParams\,OmniSharp-Extensions-LanguageServer-Protocol-Models-InitializeResult>-Handle>d__59.MoveNext() in D:\dev\csharp-language-server-protocol\src\Server\LanguageServer.cs:line 413
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at OmniSharp.Extensions.LanguageServer.Server.Pipelines.ResolveCommandPipeline`2.<Handle>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at OmniSharp.Extensions.JsonRpc.RequestRouterBase`1.<RouteRequest>d__6.MoveNext()

[david-driscoll]

I think we did finally get this merged, let us know if it's still an issue.

[rwols]

OmniSharp still sends "textDocumentSync": 0 as capability with v1.35.0 https://github.com/OmniSharp/omnisharp-roslyn/releases/tag/v1.35.0

For reference, here's a log from the SublimeText LSP plugin:

:: --> omnisharp initialize(1): {'initializationOptions': {}, 'processId': 6572, 'clientInfo': {'name': 'Sublime Text LSP'}, 'workspaceFolders': [{'name': 'python-language-server', 'uri': 'file:///D:/Development/python-language-server'}], 'rootPath': 'D:\\Development\\python-language-server', 'rootUri': 'file:///D:/Development/python-language-server', 'capabilities': {'textDocument': {'synchronization': {'willSave': True, 'didSave': True, 'willSaveWaitUntil': True}, 'references': {}, 'colorProvider': {}, 'publishDiagnostics': {'relatedInformation': True}, 'rangeFormatting': {}, 'declaration': {'linkSupport': True}, 'implementation': {'linkSupport': True}, 'completion': {'completionItemKind': {'valueSet': [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25]}, 'completionItem': {'snippetSupport': True, 'deprecatedSupport': True}}, 'codeAction': {'codeActionLiteralSupport': {'codeActionKind': {'valueSet': []}}}, 'signatureHelp': {'signatureInformation': {'documentationFormat': ['markdown', 'plaintext'], 'parameterInformation': {'labelOffsetSupport': True}}}, 'typeDefinition': {'linkSupport': True}, 'documentHighlight': {}, 'hover': {'contentFormat': ['markdown', 'plaintext']}, 'definition': {'linkSupport': True}, 'formatting': {}, 'documentSymbol': {'symbolKind': {'valueSet': [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26]}}, 'rename': {}}, 'workspace': {'configuration': True, 'executeCommand': {}, 'symbol': {'symbolKind': {'valueSet': [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26]}}, 'applyEdit': True, 'workspaceFolders': True, 'didChangeConfiguration': {}}, 'experimental': {}}}
:: <<< omnisharp 1: {'capabilities': {'completionProvider': {'triggerCharacters': ['.'], 'resolveProvider': False}, 'documentSymbolProvider': True, 'documentRangeFormattingProvider': True, 'hoverProvider': True, 'textDocumentSync': 0, 'codeLensProvider': {'resolveProvider': True}, 'documentHighlightProvider': False, 'experimental': {}, 'documentOnTypeFormattingProvider': {'firstTriggerCharacter': ';', 'moreTriggerCharacter': ['}', ')']}, 'workspaceSymbolProvider': False, 'definitionProvider': True, 'documentFormattingProvider': True, 'signatureHelpProvider': {'triggerCharacters': ['.', '?', '[']}, 'renameProvider': {'prepareProvider': False}, 'referencesProvider': True}}

I'm starting OmniSharp in a straightforward way. This is SublimeText-specific, but for reference here's my setup:

        "omnisharp":
        {
            "enabled": true,
            "command":
            [
                "C:/Users/Raoul/Downloads/OmniSharp/OmniSharp.exe",
                "--languageserver"
            ],
            "scopes": ["source.cs"],
            "syntaxes": ["Packages/C#/C#.sublime-syntax"],
            "languageId": "csharp"
        },

[razzmatazz]

I believe omnisharp-roslyn was not updated to the latest csharp-language-server-protocol itself. I tried to do a PR to fix that, but some things are clearly not working for now (CI fails).

Maybe @david-driscoll could take a look..

• https://github.com/OmniSharp/omnisharp-roslyn/pull/1754/files#diff-3137a5900d64a6b5a919a6325f1198cfR66