Working with neovim / packaging to nixpkgs

[megapixel-code]

Hi, I am currently trying to package this lsp to nixpkgs.

I think that I have managed to compile pasls, paslsproxy and paslssock, at the end I have 3 executables.

I compiled them using lazbuild like so (with ${lazarus} being the path to lazarus src files)

lazbuild --lazarusdir=${lazarus}/share/lazarus \
  src/protocol/lspprotocol.lpk \
  src/serverprotocol/lspserver.lpk \
  src/standard/pasls.lpi

lazbuild --lazarusdir=${lazarus}/share/lazarus \
  src/protocol/lspprotocol.lpk \
  src/serverprotocol/lspserver.lpk \
  src/proxy/paslsproxy.lpi

lazbuild --lazarusdir=${lazarus}/share/lazarus \
  src/protocol/lspprotocol.lpk \
  src/serverprotocol/lspserver.lpk \
  src/socketserver/paslssock.lpi

all 3 programs have -h flag it seems with the folowing output :

cmd:
pasls -h

output:
Pascal Language Server [2026/04/15]

Environment Variables:
  ▶ PP: Path to Free Pascal compiler executable
  ▶ FPCDIR: Path to FPC source directory
  ▶ LAZARUSDIR: Path to Lazarus source directory
  ▶ FPCTARGET: Target OS (e.g., darwin, linux, win64)
  ▶ FPCTARGETCPU: Target CPU (e.g., x86_64, aarch64)

Initialization Options:
  ▶ program: Path to the main program file for resolving references (string)
  ▶ fpcOptions: FPC compiler options (passed to Code Tools) (array)
  ▶ codeToolsConfig: Optional codetools.config file to load settings from (string)
  ▶ maximumCompletions: Maximum number of completion items to be returned (integer, default: 200)
  ▶ overloadPolicy: Policy which determines how overloaded document symbols are displayed (enumeration, default: 3)
  ▶ insertCompletionsAsSnippets: Procedure completions with parameters are inserted as snippets (boolean, default: true)
  ▶ insertCompletionProcedureBrackets: Procedure completions with parameters insert empty brackets (boolean, default: false)
  ▶ includeWorkspaceFoldersAsUnitPaths: Workspace folders will be added to unit paths (i.e. -Fu) (boolean, default: true)
  ▶ includeWorkspaceFoldersAsIncludePaths: Workspace folders will be added to include paths (i.e. -Fi) (boolean, default: true)
  ▶ excludeWorkspaceFolders: Workspace folder paths to exclude from workspace path collection (array)
  ▶ checkSyntax: Syntax will be checked when file opens or saves (boolean, default: false)
  ▶ publishDiagnostics: Syntax errors will be published as diagnostics (boolean, default: false)
  ▶ workspaceSymbols: Enable workspace symbols (boolean, default: true)
  ▶ documentSymbols: Enable document symbols (boolean, default: true)
  ▶ minimalisticCompletions: Completions contain a minimal amount of extra information (boolean, default: false)
  ▶ showSyntaxErrors: Syntax errors as shown in the UI with 'window/showMessage' (boolean, default: false)
  ▶ ignoreTextCompletions: Ignores completion items like "begin" and "var" (boolean, default: true)
  ▶ config: Config file or directory to read settings from (string)
  ▶ scanFilePatterns: File patterns for workspace scanning (array of glob patterns, e.g. ["*.pas", "*.pp"]) (array)
  ▶ checkInactiveRegions: Check inactive regions (boolean, default: true)
  ▶ flatSymbolMode: Force flat symbol mode (SymbolInformation[]) instead of hierarchical (boolean, default: false)
  ▶ excludeSymbols: Array of symbol types to exclude: sectionContainers, interfaceMethodDecls, implClassDefs, fields, properties, 
constants, enumMembers (array)

Server Capabilities:
  ▶ textDocumentSync: Document synchronization mode
  ▶ workspace: Workspace capabilities
  ▶ completionProvider: Code completion support (triggers: '.', '^')
  ▶ hoverProvider: Hover information support
  ▶ definitionProvider: Go to definition support
  ▶ declarationProvider: Go to declaration support
  ▶ referencesProvider: Find all references support
  ▶ implementationProvider: Go to implementation support
  ▶ documentHighlightProvider: Document highlight support
  ▶ workspaceSymbolProvider: Workspace symbols support
  ▶ signatureHelpProvider: Signature help support (triggers: '(', ')', ',')
  ▶ executeCommandProvider: Execute command support
  ▶ renameProvider
  ▶ executeCommandProvider (commands: pasls.formatCode, pasls.completeCode, pasls.invertAssignment, pasls.removeEmptyMethods, pasl
s.removeUnusedUnits)

For more information: https://github.com/genericptr/pascal-language-server

cmd:
paslsproxy -h

output:
Pascal Language Server Proxy [2026/04/15]
Usage: /nix/store/kc6vwl6lhfjgq5psam6a2dg7vw2r22jq-pascal-language-server-01-02-2026/bin/paslsproxy [options]
Where options is one or more of:
-h  --help           This help message
-c  --config=FILE    Read configuration from file FILE. Default is to read from /etc/paslsproxy.cfg
-l  --log=FILE       Set log file in which to write all log messages
-p  --port=NNN       Listen on port NNN (default: 9898
-t  --test           Interpret non-option arguments as call/param file pairs and send to server
-u  --unix=FILE      Listen on unix socket FILE (only on unix-like systems. Default: )
Only one of -p or -u may be specified, if none is specified then the default is to listen on port 9898

cmd:
paslssock -h

output:
Heap dump by heaptrc unit of /nix/store/kc6vwl6lhfjgq5psam6a2dg7vw2r22jq-pascal-language-server-01-02-2026/bin/paslssock
3473 memory blocks allocated : 18389508/18400816
3473 memory blocks freed     : 18389508/18400816
0 unfreed memory blocks : 0
True heap size : 1605632
True free heap : 1605632

0 is fpcsrcdir correct, what files are suposed to be in this folder?

could you provide the output of ls -lA of your fpcsrcdir so i can understand what folder is it suposed to be ? (and use the find cmd to search for it)

1 Is it possible to test if the executables are compiled correctly ?

What cmd can I run to test if the lsp is working as expected ?

2 Nvim

I am trying to test it on neovim but for the life of me I am not able to get it working.

CheckHealth output

vim.lsp: Active Clients ~
- pasls (id: 1)
  - Version: ? (no serverInfo.version response)
  - Root directory: ~/documents/git/nixpkgs
  - Command: { "pasls" }
  - Settings: {}
  - Attached buffers: 1

lsp.log file when opening a .pas file ("/home/usr" have been changed to ~)

[START][2026-04-15 14:54:07] LSP logging initiated
[ERROR][2026-04-15 14:54:07] ...-unwrapped-0.12.1/share/nvim/runtime/lua/vim/lsp/log.lua:151	"rpc"	"pasls"	"stderr"	"✓ RootURI: file://~/documents/git/nixpkgs\r✓ ProjectDir: ~/documents/git/nixpkgs/\r\n"
[ERROR][2026-04-15 14:54:08] ...-unwrapped-0.12.1/share/nvim/runtime/lua/vim/lsp/log.lua:151	"rpc"	"pasls"	"stderr"	"✓ Server: 2026/04/15\r✓ Client: Neovim 0.12.1\r\n✓ FPCPath: /nix/store/8yxxda9bacqqa7671ngswmacxravl5pf-fpc-3.2.2/bin/ppcx64\r\n✓ FPCSrcDir: /nix/store/xa8rnm8m85qh9ivg6wbf6bkfsmcz7f9v-lazarus-gtk2-4.4-0/share/fpcsrc\r\n✓ LazarusSrcDir: /nix/store/xa8rnm8m85qh9ivg6wbf6bkfsmcz7f9v-lazarus-gtk2-4.4-0/share/lazarus\r\n✓ TargetOS: Linux\r\n✓ TargetProcessor: x86_64\r\n✓ Working directory: ~/documents/git/nixpkgs/pkgs/by-name\r\n✓ FPCOptions:\r\n  -Fu~/documents/git/nixpkgs/pkgs/os-specific/bsd/freebsd/pkgs/iwlwifi-firmware/src/\r\n  -Fi~/documents/git/nixpkgs/pkgs/os-specific/bsd/freebsd/pkgs/iwlwifi-firmware/src/\r\n✓ ProjectDir: ~/documents/git/nixpkgs/\r\n✓ Settings:\r\n  ► maximumCompletions: 200\r\n  ► overloadPolicy: Suffix\r\n  ► insertCompletionsAsSnippets: True\r\n  ► insertCompletionProcedureBrackets: False\r\n  ► includeWorkspaceFoldersAsUnitPaths: True\r\n  ► includeWorkspaceFoldersAsIncludePaths: True\r\n  ► checkSyntax: False\r\n  ► publishDiagnostics: False\r\n  ► workspaceSymbols: True\r\n  ► documentSymbols: True\r\n  ► minimalisticCompletions: False\r\n  ► showSyntaxErrors: False\r\n  ► flatSymbolMode: False\r\n"
[ERROR][2026-04-15 14:54:08] ...-unwrapped-0.12.1/share/nvim/runtime/lua/vim/lsp/log.lua:151	"rpc"	"pasls"	"stderr"	"Checking inactive regions\r"

Same output but changing the "\n\r" with real \n, and removing the [error][time] ...

"✓ RootURI: file://~/documents/git/nixpkgs✓ ProjectDir: ~/documents/git/nixpkgs/
"
"✓ Server: 2026/04/15✓ Client: Neovim 0.12.1
✓ FPCPath: /nix/store/8yxxda9bacqqa7671ngswmacxravl5pf-fpc-3.2.2/bin/ppcx64
✓ FPCSrcDir: /nix/store/xa8rnm8m85qh9ivg6wbf6bkfsmcz7f9v-lazarus-gtk2-4.4-0/share/fpcsrc
✓ LazarusSrcDir: /nix/store/xa8rnm8m85qh9ivg6wbf6bkfsmcz7f9v-lazarus-gtk2-4.4-0/share/lazarus
✓ TargetOS: Linux
✓ TargetProcessor: x86_64
✓ Working directory: ~/documents/git/nixpkgs/pkgs/by-name
✓ FPCOptions:
  -Fu~/documents/git/nixpkgs/pkgs/os-specific/bsd/freebsd/pkgs/iwlwifi-firmware/src/
  -Fi~/documents/git/nixpkgs/pkgs/os-specific/bsd/freebsd/pkgs/iwlwifi-firmware/src/
✓ ProjectDir: ~/documents/git/nixpkgs/
✓ Settings:
  ► maximumCompletions: 200
  ► overloadPolicy: Suffix
  ► insertCompletionsAsSnippets: True
  ► insertCompletionProcedureBrackets: False
  ► includeWorkspaceFoldersAsUnitPaths: True
  ► includeWorkspaceFoldersAsIncludePaths: True
  ► checkSyntax: False
  ► publishDiagnostics: False
  ► workspaceSymbols: True
  ► documentSymbols: True
  ► minimalisticCompletions: False
  ► showSyntaxErrors: False
  ► flatSymbolMode: False
"
"Checking inactive regions"

I do not know how to change the defaults settings I have tried to pass using the following configs

vim.lsp.config ( "pasls", {
   capabilities = capabilities,
   cmd = { "pasls" },
   initializationOptions = {
      maximumCompletions = 100,
      publishDiagnostics = true,
      checkSyntax = true,
      showSyntaxErrors = true,
      documentSymbols = true,
   },
})

-- or i also tryed this

vim.lsp.config ( "pasls", {
   capabilities = capabilities,
   cmd = { "pasls" },
   settings = {
      maximumCompletions = 100,
      publishDiagnostics = true,
      checkSyntax = true,
      showSyntaxErrors = true,
      documentSymbols = true,
   },
})

Any pointer on something I am missing ?

[chicken2006]

0: Looks correct. Here is mine

total 280
drwxr-xr-x 1 username wheel  4096 Jul 10 07:52 .git
-rw-r--r-- 1 username wheel   127 May  9 11:32 .gitattributes
-rw-r--r-- 1 username wheel   618 May  9 11:32 .gitconfig
-rw-r--r-- 1 username wheel  1429 May 28 11:30 .gitignore
drwxr-xr-x 1 username wheel     0 May  9 11:32 .gitlab
-rw-r--r-- 1 username wheel  4624 Jul 10 07:25 .gitlab-ci.yml
-rw-r--r-- 1 username wheel 19284 May  9 11:32 LICENSE
-rw-r--r-- 1 username wheel 87536 May  9 11:32 Makefile
-rw-r--r-- 1 username wheel 10083 May  9 11:32 Makefile.fpc
-rw-r--r-- 1 username wheel   727 May  9 11:32 README.md
-rw-r--r-- 1 username wheel     6 Jul 10 07:52 base.build-stamp.x86_64-linux
-rw-r--r-- 1 username wheel     6 Jul 10 07:52 build-stamp.x86_64-linux
drwxr-xr-x 1 username wheel 61440 Jul 10 07:53 compiler
-rw-r--r-- 1 username wheel  1225 May  9 11:32 fpmake.pp
-rw-r--r-- 1 username wheel   252 May  9 11:32 fpmake_add1.inc
-rw-r--r-- 1 username wheel   188 May  9 11:32 fpmake_proc1.inc
drwxr-xr-x 1 username wheel  4096 May 28 11:30 installer
drwxr-xr-x 1 username wheel 40960 Jul 10 07:49 packages
drwxr-xr-x 1 username wheel 16384 Jul 10 07:52 rtl
drwxr-xr-x 1 username wheel  4096 May  9 11:33 tests
drwxr-xr-x 1 username wheel  8192 Jul 10 07:52 utils

1: There is a file named testlsp.lpi in src/tests. You need to build the binary in order to do that
2: It should be init_options. Here is my config:

vim.lsp.config('pasls', {
  on_attach = function(client, bufnr)
    base.on_attach(client, bufnr)

    local opts = { buffer = bufnr, silent = true }
    vim.keymap.set("n", "gD", vim.lsp.buf.declaration, opts)
    vim.keymap.set("n", "gd", vim.lsp.buf.definition, opts)
  end,
  on_init = on_init,
  capabilities = capabilities,
  cmd = { "/home/username/.local/bin/pasls" },
  filetypes = { "pascal" },
  root_dir = function(bufnr, on_dir)
    local fname = vim.api.nvim_buf_get_name(bufnr)
    on_dir(util.root_pattern('*.lpi', '*.lpk', '.git', 'Makefile.fpc')(fname))
  end,

  cmd_env = {
    -- Path to FPC sources such as `/usr/local/share/fpcsrc`
    FPCDIR='/run/media/username/F88ECC0B8ECBC07C/pascal/fpcsrc',

    -- Path to compile (i.e. `/usr/bin/fpc`, `/usr/bin/ppc386`)
    PP='/run/media/username/F88ECC0B8ECBC07C/pascal/fpc/bin/x86_64-linux/ppcx64',

    -- Path to Lazarus sources as `/usr/local/share/lazsrc`
    LAZARUSDIR='/run/media/username/F88ECC0B8ECBC07C/pascal/lazarus',

    -- Target platform (`windows`, `linux`, `darwin`)
    FPCTARGET='linux',

    -- Target CPU such as `x86_64`
    FPCTARGETCPU='x86_64',
  },

  init_options = {
    -- Path to the main program file for resolving references (if not available the path of the current document will be used)
    program = "/run/media/username/F88ECC0B8ECBC07C/pascal/fpc/bin/x86_64-linux/fpc",

    -- Compiler flags to specify paths, macros, etc.
    -- Example: {"-Fu/path/to/units", "-Fi/path/to/includes", "-dMY_MACRO"}
    fpcOptions = {"-Fu$(root)/units", "-Fi$(root)/src", "-n @/run/media/username/F88ECC0B8ECBC07C/pascal/fpc/bin/x86_64-linux/fpc.cfg"},

    -- Maximum number of completions returned per query
    maximumCompletions = 100,

    -- Path to symbols database file for faster symbol queries
    -- Example: "$(tmpdir)/pasls-symbols.db" or "/path/to/symbols.db"
    symbolDatabase = "$(tmpdir)/symbols.db",

    -- Preferred method to handle overloaded functions in document symbol requests
    -- 1: Duplicate function names appear in the list
    -- 2: After the original definition ignore others
    -- 3: Add a suffix which denotes the overload count
    overloadPolicy = 3,

    -- Insert procedure completions with parameters as snippets
    insertCompletionsAsSnippets = true,

    -- Insert empty brackets for procedure completions
    insertCompletionProcedureBrackets = true,

    -- Add workspace folders to unit paths (-Fu)
    includeWorkspaceFolderAsUnitPaths = true,

    -- Add workspace folders to include paths (-Fi)
    includeWorkspaceFolderAsIncludePaths = true,

    -- Workspace folder paths to exclude from workspace path collection
    -- Example: {"/path/to/workspace/node_modules", "/path/to/workspace/vendor"}
    excludeWorkspaceFolders = {},

    -- Check syntax when file opens or saves
    checkSyntax = true,

    -- Mark inactive regions based on conditional compilation directives
    checkInactiveRegions = true,

    -- Publish syntax errors as diagnostics
    publishDiagnostics = true,

    -- Enable workspace symbols
    workspaceSymbols = true,

    -- Enable document symbols
    documentSymbols = true,

    -- Completions contain minimal extra information
    minimalisticCompletions = true,

    -- Show syntax errors in UI with window/showMessage
    showSyntaxErrors = true,

    -- Config file or directory to read settings from
    config = "$(root)/jcfsettings.cfg",
  },
})

[megapixel-code]

Hi, first thanks so much for your help. been making a lot of progress thanks to you !

I now have a executable capable of talking with nvim ;)

But now everytime I start typing into a pascal file i get the following message :

LSP[pasls] ⚠️ /home/username/documents/temp.pas: "unit not found: fpextres" @ -1:1;

• Have you encountered this ?
• Any pointers on how to fix this ? (from what I could find pasls doesnt have access to the lazarus runtime library, but i do not understand why since i give the LAZARUSDIR path in the environement)

I am using the src/build_fpc.sh script to compile the program.

[mvancanneyt]

This error usually means Lazarus does not find the FPC sources. Either they are missing from the lazarus setup or the lazarus setup has the wrong FPC directory.

[megapixel-code]

To be honest I am a complete beginer in pascal.

what do you mean by lazarus setup ?

I am stuck, I dont really understand what I am doing wrong.

setup

Right now I am packaging it in 2 steps

1: compiling

Right now I am compiling the program using the src/build_fpc.sh script. (I use a modified version #157 ).

runing it with the following env variables :

LAZARUSDIR=${lazarus}/share/lazarus
FPC=${fpc}/bin/fpc
FPC_CFG=${fpc}/etc/fpc.cfg

NOTE: fpc.cfg is not in the same directory as the fpc executable of the path.

with :

ls -lA $LAZARUSDIR

dr-xr-xr-x 91 root root 4.0K 1970-01-01  components/
dr-xr-xr-x  2 root root 4.0K 1970-01-01  converter/
dr-xr-xr-x  4 root root 4.0K 1970-01-01  debugger/
dr-xr-xr-x  2 root root 4.0K 1970-01-01  designer/
dr-xr-xr-x  5 root root 4.0K 1970-01-01  doceditor/
dr-xr-xr-x  8 root root 4.0K 1970-01-01  docs/
dr-xr-xr-x 89 root root 4.0K 1970-01-01  examples/
dr-xr-xr-x  5 root root  16K 1970-01-01  ide/
dr-xr-xr-x 21 root root 4.0K 1970-01-01  images/
dr-xr-xr-x  2 root root 4.0K 1970-01-01  languages/
dr-xr-xr-x  3 root root 4.0K 1970-01-01  lazarus.app/
dr-xr-xr-x 13 root root 4.0K 1970-01-01  lcl/
dr-xr-xr-x  6 root root 4.0K 1970-01-01  packager/
dr-xr-xr-x 11 root root 4.0K 1970-01-01  test/
dr-xr-xr-x 14 root root 4.0K 1970-01-01  tools/
dr-xr-xr-x  3 root root 4.0K 1970-01-01  units/
-r--r--r--  5 root root  18K 1970-01-01  COPYING.GPL.txt
-r--r--r--  5 root root  25K 1970-01-01  COPYING.LGPL.txt
-r--r--r--  3 root root 1.3K 1970-01-01  COPYING.modifiedLGPL.txt
-r--r--r--  3 root root 1.5K 1970-01-01  COPYING.txt
-r--r--r--  2 root root  99K 1970-01-01  Makefile
-r--r--r--  3 root root  15K 1970-01-01  Makefile.fpc
-r-xr-xr-x  2 root root 169M 1970-01-01  lazarus
-r-xr-xr-x  2 root root  51M 1970-01-01  lazbuild
-r-xr-xr-x  2 root root  44M 1970-01-01  startlazarus

2: wrapping

I create a wrapper for the pasls executable with the following environement variable :

FPCDIR=${lazarus}/share/fpcsrc
PP=${fpc}/bin/fpc
LAZARUSDIR=${lazarus}/share/lazarus

FPCDIR is the dir on the left-handside :

LAZARUSDIR is the same dir as before.

[chicken2006]

“Lazarus setup” means the Lazarus settings. Could you check if the FPC source path is set correctly by going to Tools → Options → Environment → Files → FPC sources in Lazarus?