ranges for textDocument/rangeFormatting are wrong

[jyn514]

rust-analyzer version: rust-analyzer 1.86.0-nightly (f7cc13a 2025-01-25)

rustc version: rustc 1.86.0-nightly (f7cc13af8 2025-01-25)

rustfmt version: rustfmt 1.8.0-nightly (f7cc13af82 2025-01-25)

editor or extension: neovim 0.10.4, lspconfig 1.6.0 00dae9f

relevant settings:

-- can skip these first two lines if you have a plugin manager
local lazypath = vim.fn.stdpath("data") .. "/lazy/nvim-lspconfig"
vim.opt.rtp:prepend(lazypath)

local lspconfig = require('lspconfig')
local settings = { ['rust-analyzer'] = { rustfmt = { rangeFormatting = { enable = true } } } }
lspconfig.rust_analyzer.setup {
    settings = settings,
    -- https://github.com/rust-lang/rust-analyzer/issues/17301
    init_options = settings,
    on_init = function(client)
        -- the real code checks if rustfmt is nightly or not
        vim.opt_local.formatexpr = 'v:lua.vim.lsp.formatexpr()'
        client.on_attach = function()
            vim.opt_local.formatexpr = 'v:lua.vim.lspformatexpr()'
        end
    end
}

code snippet to reproduce:

fn main() {
    let unit_offsets_cache = collect(dwarf.units  ())  ?;
}

steps to reproduce:

1. verify that formatting with RA is enabled: set formatexpr? (should show formatexpr=v:lua.vim.lsp.formatexpr())
2. move your cursor to line 2. run Vgq to format the current line. observe that nothing happens.
3. move your cursor to line 3. run Vgq. observe that line 2 is formatted.

I debugged that nvim is sending 0-indexed lines, so maybe RA or rustfmt is expecting 1-indexed lines?

[jyn514]

if i fix that off by one error

(you don't want to know how)

-- copied directly from vim.lsp.formatexpr, except not off-by-one
function formatexpr(opts)
  opts = opts or {}
  local timeout_ms = opts.timeout_ms or 500
  local ms = vim.lsp.protocol.Methods

  if vim.list_contains({ 'i', 'R', 'ic', 'ix' }, vim.fn.mode()) then
    -- `formatexpr` is also called when exceeding `textwidth` in insert mode
    -- fall back to internal formatting
    return 1
  end

  local start_lnum = vim.v.lnum
  local end_lnum = start_lnum + vim.v.count - 1

  if start_lnum <= 0 or end_lnum <= 0 then
    return 0
  end
  local bufnr = vim.api.nvim_get_current_buf()
  for _, client in pairs(vim.lsp.get_clients({ bufnr = bufnr })) do
    if client.supports_method(ms.textDocument_rangeFormatting) then
      local params = vim.lsp.util.make_formatting_params()
      local end_line = vim.fn.getline(end_lnum) --[[@as string]]
      local end_col = vim.lsp.util._str_utfindex_enc(end_line, nil, client.offset_encoding)
      --- @cast params +lsp.DocumentRangeFormattingParams
      params.range = {
        start = {
          line = start_lnum,
          character = 0,
        },
        ['end'] = {
          line = end_lnum,
          character = end_col,
        },
      }
      print('line_start: '..tostring(params.range.start.line)..', line_end: '..tostring(params.range['end'].line), 'column_start: '..tostring(0)..', column_end: '..tostring(end_col))
      local response =
        client.request_sync(ms.textDocument_rangeFormatting, params, timeout_ms, bufnr)
      if response and response.result then
        vim.lsp.util.apply_text_edits(response.result, bufnr, client.offset_encoding)
        return 0
      end
    end
  end

  -- do not run builtin formatter.
  return 0
end

then things mostly work. but consider this statement:

        let sup_offsets_cache = if let Some(sup) = dwarf.sup( ) {
            collect(sup.units() )?
        } else {
            Vec::new( )
        };

highlighting all 5 lines at once works fine. and highlighting the first 2 lines also works fine. but highlighting only line 4, or only line 2, or lines 3-5, does not work. probably this is a rustfmt bug because it can't work with partial ASTs?

[jyn514]

highlighting all 5 lines at once works fine. and highlighting the first 2 lines also works fine. but highlighting only line 4, or only line 2, or lines 3-5, does not work. probably this is a rustfmt bug because it can't work with partial ASTs?

yeah this is rust-lang/rustfmt#4053, not an RA bug