It seems like I am to stupid to setup the arduino_language_server properly.

[Xyhlon]

It doesn't attach to the buffer, yet in LspInfo it lists it as compatible.

Notify gives me the following message

Spawning language server with cmd: `arduino-language-server` failed. The language server is either not installed, missing from PATH, or not executable.

My setup was installing the lsp with LspInstall. it didn't attach. then I tried to set some of the config as it was written in the docs:

local lspconfig = require "lspconfig"
lspconfig.arduino_language_server.setup {
  cmd = {
    -- Required
    "arduino-language-server",
    "-cli-config",
    "~/.arduino15/arduino-cli.yaml",
    -- Optional
    -- "-cli",
    -- "/usr/bin/arduino-cli",
    -- "-clangd",
    -- "/usr/bin/clangd",

    "-fqbn",
    "arduino:avr:uno",
  },
  -- root_dir = lspconfig.util.find_git_ancestor,
  root_dir = function(fname)
    -- P(vim.fn.expand "%:p:h")
    -- return vim.fn.expand "%:p:h"
    local root_files = { vim.fn.expand "%" }
    P(fname)
    P(root_files)
    local primary = lspconfig.util.root_pattern(unpack(root_files))(fname)
    P(primary)
    return primary
  end,
  filetypes = { "arduino", "ino" },
}

I tried all sorts of combinations, yet nothing worked.
Could somebody tell me what I am doing wrong.
clangd and arduino-cli are installed

[williamboman]

Hello! Have you set up nvim-lsp-installer (require("nvim-lsp-installer").setup {})?

[Xyhlon]

No I haven't explicitly. But now I tried it explicitly and it didnt change anything

[williamboman]

Do you get any error message or other logs indicating what the problem may be? Check :h lspconfig-debugging and :h lspconfig-logging

[Xyhlon]

without the debug lua snippet

[START][2022-06-18 16:44:48] LSP logging initiated
[ERROR][2022-06-18 16:44:48] .../vim/lsp/rpc.lua:430	"rpc"	"arduino-language-server"	"stderr"	"2022/06/18 16:44:48 ArduinoCLI daemon address and instance number must be set.\n"

with the debug lua snippet

[START][2022-06-18 16:57:04] LSP logging initiated
[INFO][2022-06-18 16:57:04] .../vim/lsp/rpc.lua:265	"Starting RPC client"	{
  args = { "-cli-config", "~/.arduino15/arduino-cli.yaml", "-fqbn", "arduino:avr:uno" },
  cmd = "arduino-language-server",
  extra = {
    cwd = "/home/bob/lab/Lab-Reports/ECM/MicroController/ampel",
    env = {
      PATH = "/home/bob/.local/share/nvim/lsp_servers/arduino_language_server:/home/bob/.local/bin:/home/bob/Applications:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/var/lib/snapd/snap/bin"
    }
  }
}
[TRACE][2022-06-18 16:57:04] .../lua/vim/lsp.lua:1072	"LSP[arduino_language_server]"	"initialize_params"	{
  capabilities = {
    callHierarchy = {
      dynamicRegistration = false
    },
    textDocument = {
      codeAction = {
        codeActionLiteralSupport = {
          codeActionKind = {
            valueSet = { "", "Empty", "QuickFix", "Refactor", "RefactorExtract", "RefactorInline", "RefactorRewrite", "Source", "SourceOrganizeImports", "quickfix", "refactor", "refactor.extract", "refactor.inline", "refactor.rewrite", "source", "source.organizeImports" }
          }
        },
        dataSupport = true,
        dynamicRegistration = false,
        isPreferredSupport = true,
        resolveSupport = {
          properties = { "edit" }
        }
      },
      completion = {
        completionItem = {
          commitCharactersSupport = false,
          deprecatedSupport = false,
          documentationFormat = { "markdown", "plaintext" },
          preselectSupport = false,
          snippetSupport = false
        },
        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 }
        },
        contextSupport = false,
        dynamicRegistration = false
      },
      declaration = {
        linkSupport = true
      },
      definition = {
        linkSupport = true
      },
      documentHighlight = {
        dynamicRegistration = false
      },
      documentSymbol = {
        dynamicRegistration = false,
        hierarchicalDocumentSymbolSupport = true,
        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 }
        }
      },
      hover = {
        contentFormat = { "markdown", "plaintext" },
        dynamicRegistration = false
      },
      implementation = {
        linkSupport = true
      },
      publishDiagnostics = {
        relatedInformation = true,
        tagSupport = {
          valueSet = { 1, 2 }
        }
      },
      references = {
        dynamicRegistration = false
      },
      rename = {
        dynamicRegistration = false,
        prepareSupport = true
      },
      signatureHelp = {
        dynamicRegistration = false,
        signatureInformation = {
          activeParameterSupport = true,
          documentationFormat = { "markdown", "plaintext" },
          parameterInformation = {
            labelOffsetSupport = true
          }
        }
      },
      synchronization = {
        didSave = true,
        dynamicRegistration = false,
        willSave = false,
        willSaveWaitUntil = false
      },
      typeDefinition = {
        linkSupport = true
      }
    },
    window = {
      showDocument = {
        support = false
      },
      showMessage = {
        messageActionItem = {
          additionalPropertiesSupport = false
        }
      },
      workDoneProgress = true
    },
    workspace = {
      applyEdit = true,
      configuration = true,
      symbol = {
        dynamicRegistration = false,
        hierarchicalWorkspaceSymbolSupport = true,
        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 }
        }
      },
      workspaceEdit = {
        resourceOperations = { "rename", "create", "delete" }
      },
      workspaceFolders = true
    }
  },
  clientInfo = {
    name = "Neovim",
    version = "0.8.0"
  },
  initializationOptions = vim.empty_dict(),
  processId = 2743113,
  rootPath = "/home/bob/lab/Lab-Reports/ECM/MicroController/ampel",
  rootUri = "file:///home/bob/lab/Lab-Reports/ECM/MicroController/ampel",
  trace = "off",
  workspaceFolders = { {
      name = "/home/bob/lab/Lab-Reports/ECM/MicroController/ampel",
      uri = "file:///home/bob/lab/Lab-Reports/ECM/MicroController/ampel"
    } }
}
[DEBUG][2022-06-18 16:57:04] .../vim/lsp/rpc.lua:355	"rpc.send"	{
  id = 1,
  jsonrpc = "2.0",
  method = "initialize",
  params = {
    capabilities = {
      callHierarchy = {
        dynamicRegistration = false
      },
      textDocument = {
        codeAction = {
          codeActionLiteralSupport = {
            codeActionKind = {
              valueSet = { "", "Empty", "QuickFix", "Refactor", "RefactorExtract", "RefactorInline", "RefactorRewrite", "Source", "SourceOrganizeImports", "quickfix", "refactor", "refactor.extract", "refactor.inline", "refactor.rewrite", "source", "source.organizeImports" }
            }
          },
          dataSupport = true,
          dynamicRegistration = false,
          isPreferredSupport = true,
          resolveSupport = {
            properties = { "edit" }
          }
        },
        completion = {
          completionItem = {
            commitCharactersSupport = false,
            deprecatedSupport = false,
            documentationFormat = { "markdown", "plaintext" },
            preselectSupport = false,
            snippetSupport = false
          },
          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 }
          },
          contextSupport = false,
          dynamicRegistration = false
        },
        declaration = {
          linkSupport = true
        },
        definition = {
          linkSupport = true
        },
        documentHighlight = {
          dynamicRegistration = false
        },
        documentSymbol = {
          dynamicRegistration = false,
          hierarchicalDocumentSymbolSupport = true,
          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 }
          }
        },
        hover = {
          contentFormat = { "markdown", "plaintext" },
          dynamicRegistration = false
        },
        implementation = {
          linkSupport = true
        },
        publishDiagnostics = {
          relatedInformation = true,
          tagSupport = {
            valueSet = { 1, 2 }
          }
        },
        references = {
          dynamicRegistration = false
        },
        rename = {
          dynamicRegistration = false,
          prepareSupport = true
        },
        signatureHelp = {
          dynamicRegistration = false,
          signatureInformation = {
            activeParameterSupport = true,
            documentationFormat = { "markdown", "plaintext" },
            parameterInformation = {
              labelOffsetSupport = true
            }
          }
        },
        synchronization = {
          didSave = true,
          dynamicRegistration = false,
          willSave = false,
          willSaveWaitUntil = false
        },
        typeDefinition = {
          linkSupport = true
        }
      },
      window = {
        showDocument = {
          support = false
        },
        showMessage = {
          messageActionItem = {
            additionalPropertiesSupport = false
          }
        },
        workDoneProgress = true
      },
      workspace = {
        applyEdit = true,
        configuration = true,
        symbol = {
          dynamicRegistration = false,
          hierarchicalWorkspaceSymbolSupport = true,
          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 }
          }
        },
        workspaceEdit = {
          resourceOperations = { "rename", "create", "delete" }
        },
        workspaceFolders = true
      }
    },
    clientInfo = {
      name = "Neovim",
      version = "0.8.0"
    },
    initializationOptions = vim.empty_dict(),
    processId = 2743113,
    rootPath = "/home/bob/lab/Lab-Reports/ECM/MicroController/ampel",
    rootUri = "file:///home/bob/lab/Lab-Reports/ECM/MicroController/ampel",
    trace = "off",
    workspaceFolders = { {
        name = "/home/bob/lab/Lab-Reports/ECM/MicroController/ampel",
        uri = "file:///home/bob/lab/Lab-Reports/ECM/MicroController/ampel"
      } }
  }
}
[ERROR][2022-06-18 16:57:04] .../vim/lsp/rpc.lua:430	"rpc"	"arduino-language-server"	"stderr"	"2022/06/18 16:57:04 ArduinoCLI daemon address and instance number must be set.\n"

[williamboman]

So I did some digging on the error message shown at the very end. It seems like you do have to provide the -cli flag (as well as the -clangd) - this was changed here.

Try the following:

cmd = {
    "arduino-language-server",
    "-cli-config",
    "~/.arduino15/arduino-cli.yaml",
    "-cli",
    "arduino-cli",
    "-clangd",
    "clangd",
    "-fqbn",
    "arduino:avr:uno",
  }

[Xyhlon]

thx you are right the optional cli and clangd flags where not optional. now everything works as expected 😄