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D Language Server


This project is unmaintained, please use another one such as serve-d

DUB Travis AppVeyor
DUB Travis AppVeyor

LSP compliance: 3.14

This is still a work in progress; there might still be bugs and crashes

DLS implements the server side of the Language Server Protocol (LSP) for the D programming language. It doesn't do much itself (yet), and rather uses already available components, and provides an interface to work with the LSP. Current features include:

  • Code completion
  • Going to symbol definition
  • Finding references
  • Symbol renaming
  • Error checking
  • Code formatting (document, range and on-type)
  • Symbol listing (current document and workspace-wide)
  • Symbol highlighting
  • Documentation on hover
  • Random, frustrating crashes

Packages used (the stuff doing the actual hard work):



If you are using VSCode, Visual Studio or Atom, you can skip this step and install the corresponding extension.

Simply run:

dub fetch dls
dub run dls:bootstrap

to install to download and install the latest binary release. The second command will output the executable's path. DLS will automatically update itself whenever a new version is out.

Some common editors

  • Visual Studio Code: install the extension
  • Visual Studio: install the extension
  • Atom: install the package
  • Sublime Text (using tomv654's LSP client):
        "clients": {
            "dls": {
                "command": ["<PATH TO DLS EXECUTABLE>"],
                "enabled": true,
                "languageId": "d",
                "scopes": ["source.d"],
                "syntaxes": ["Packages/D/D.sublime-syntax"]
  • Vim/Neovim (using autozimu's LanguageClient-neovim):
    let g:LanguageClient_serverCommands = {
        \ 'd': ['<PATH TO DLS EXECUTABLE>']
        \ }
  • Emacs (using d-mode and lsp-mode):
    (require 'lsp)
    (add-hook 'd-mode-hook #'lsp)
            :new-connection (lsp-stdio-connection '("<PATH TO DLS EXECUTABLE>"))
            :major-modes '(d-mode)
            :server-id 'dls))

If it's not working with your editor of choice, submit a new issue !

Notes about FreeBSD

DLS is usable using FreeBSD's Linux binary compatibility system (tested on FreeBSD 12.0-RELEASE). The main steps to enable Linux binary compatibility are:

  • Adding enable_linux="YES" to /etc/rc.conf
  • Running kldload linux64
  • Running pkg install emulators/linux_base-c7 (or emulators/linux_base-c6)
  • Running pkg install ftp/linux-c7-curl (or ftp/linux-c6-curl)
  • Adding the following lines to /etc/fstab:
    linprocfs	/compat/linux/proc		linprocfs	rw				0	0
    linsysfs	/compat/linux/sys		linsysfs	rw				0	0
    tmpfs		/compat/linux/dev/shm	tmpfs		rw,mode=1777	0	0
  • Running:
    mount /compat/linux/proc
    mount /compat/linux/sys
    mount /compat/linux/dev/shm

More detailed/up-to-date information can be found in the FreeBSD documentation.

Command line options

Some command line options exist to control the behavior of DLS:

  • --stdio: use standard input and output streams for communication (default behavior)
  • --socket=<PORT> or --tcp=<PORT>: use a socket to connect on the specified port for communication
  • --version: show version information
  • --help: show full list of command line options
  • --init.*: specify an initialization option

Client side configuration

All these keys should be formatted as d.dls.[section].[key] (e.g. d.dls.format.endOfLine).

Section: symbol Type Default value
importPaths string[] []
listAllSymbols boolean false
Section: analysis Type Default value
configFile string "dscanner.ini"
filePatterns string[] []
Section: format Type Default value Builtin DFMT
engine "dfmt" or "builtin" "dfmt"
endOfLine "lf" or "cr" or "crlf" "lf"
insertFinalNewline boolean true
trimTrailingWhitespace boolean true
maxLineLength number 120
softMaxLineLength number 80
braceStyle "allman" or "otbs" or "stroustrup" "allman"
spaceAfterCasts boolean true
spaceAfterKeywords boolean true
spaceBeforeAAColons boolean false
spaceBeforeFunctionParameters boolean false
spaceBeforeSelectiveImportColons boolean true
alignSwitchStatements boolean true
compactLabeledStatements boolean true
outdentAttributes boolean true
splitOperatorsAtLineEnd boolean false
templateConstraintsStyle "conditionalNewlineIndent" or "conditionalNewline" or "alwaysNewline" or "alwaysNewlineIndent" "conditionalNewlineIndent"
templateConstraintsSingleIndent boolean false

Server initialization options

DLS supports a few custom initialization options in the InitializeParams.initializationOptions object sent with the initialize request:

interface InitializationOptions: {
    autoUpdate?: boolean = true;        // Enable auto-updating
    preReleaseBuilds?: boolean = false; // Enable pre-release updates
    safeMode?: boolean = false;         // Disable processing multiple requests in parallel
    catchErrors?: boolean = false;      // Catch and ignore errors (WARNING: UNSAFE)
    logFile?: string = "";              // Path to a file to log DLS operations
    capabilities?: {
        hover?: boolean = true;                     // Enable hover
        completion?: boolean = true;                // Enable completion
        definition?: boolean = true;                // Enable go-to-definition
        typeDefinition?: boolean = true;            // Enable go-to-type-definition
        references?: boolean = true;                // Enable references search
        documentHighlight?: boolean = true;         // Enable symbol highlighting
        documentSymbol?: boolean = true;            // Enable document symbol search
        workspaceSymbol?: boolean = true;           // Enable workspace symbol search
        codeAction?: boolean = true;                // Enable code actions
        documentFormatting?: boolean = true;        // Enable formatting
        documentRangeFormatting?: boolean = true;   // Enable range formatting
        documentOnTypeFormatting?: boolean = true;  // Enable on type formatting
        rename?: boolean = true;                    // Enable renaming
    symbol?: {
        autoImports?: boolean = true;   // Automatically import projects and their dependencies

Every initialization option can be toggled via a command line option. Example: ./dls --init.logFile=path/to/file.log. Initialization options set suring the initialization phase will override ones set with command line options.


The server may delegate a few operations to the client-side extension depending on the language client's capabilities. The client should watch these files for the server to work properly:

  • dub.selections.json
  • dub.json
  • dub.sdl
  • .gitmodules
  • *.ini

If the client supports dynamic registration of the workspace/didChangeWatchedFiles method, then the server will automatically register file watching. If the client doesn't support dynamic registration however, the client-side extension will need to manually do it. The server needs to know at least when dub.selections.json files change to properly provide completion support. If dub.json and dub.sdl are also watched, dub.selections.json can be regenerated on demand. Watching *.ini allows DLS to monitor D-Scanner config files, even if the name is changed in the config and isn't dscanner.ini.

Custom messages

Since the LSP defines messages with methods starting in $/ to be implementation dependant, DLS uses $/dls as a prefix for custom messages.

Message Type Parameters Description
$/dls/upgradeDls/didStart Notification TranslationParams Sent when the upgrade process starts
$/dls/upgradeDls/didStop Notification null Sent when the upgrade process stops
$/dls/upgradeDls/didChangeTotalSize Notification DlsUpgradeSizeParams Sent during the download, with the total size of the upgrade download
$/dls/upgradeDls/didChangeCurrentSize Notification DlsUpgradeSizeParams Sent during the download, with the current size of the upgrade download
$/dls/upgradeDls/didExtract Notification TranslationParams Sent when the download is finished and the contents are written on the disk
$/dls/upgradeSelections/didStart Notification TranslationParams Sent when DLS starts upgrading dub.selections.json
$/dls/upgradeSelections/didStop Notification null Sent when DLS has finished upgrading dub.selections.json
interface TranslationParams {
    tr: string;

interface DlsUpgradeSizeParams extends TranslationParams {
    size: number;



The file i18n/data/translations.json contains localization strings. Adding new strings is straightforward, simply add new entries in the message objects with the locale identifier as key and the translated string as value.

Which branch should be targeted by pull requests ?

  • Is it work on a new feature ? Then the master branch should be targeted.
  • Is it a fix ? Then the latest release/v<MAJOR>.<MINOR>.x branch should be targeted.


To run automated tests, run dub test --main-file=tests/main.d.

Other links