fix: format_after_save blocks on exit for lsp formatting

3 files changed, 29 insertions, 8 deletions

diff --git a/lua/conform/lsp_format.lua b/lua/conform/lsp_format.lua
index 0315314..17d835f 100644
--- a/lua/conform/lsp_format.lua
+++ b/lua/conform/lsp_format.lua
@@ -1,4 +1,5 @@
 ---This module replaces the default vim.lsp.buf.format() so that we can inject our own logic
+local log = require("conform.log")
 local util = require("vim.lsp.util")
 
 local M = {}
@@ -75,12 +76,22 @@ function M.format(options, callback)
         return callback()
       end
       local params = set_range(client, util.make_formatting_params(options.formatting_options))
+      local auto_id = vim.api.nvim_create_autocmd("LspDetach", {
+        buffer = bufnr,
+        callback = function(args)
+          if args.data.client_id == client.id then
+            log.warn("LSP %s detached during format request", client.name)
+            callback("LSP detached")
+          end
+        end,
+      })
       client.request(method, params, function(err, result, ctx, _)
+        vim.api.nvim_del_autocmd(auto_id)
         if not result then
           return callback(err or "No result returned from LSP formatter")
         elseif not vim.api.nvim_buf_is_valid(bufnr) then
           return callback("buffer was deleted")
-        elseif vim.b[bufnr].changedtick ~= changedtick then
+        elseif changedtick ~= util.buf_get_changedtick(bufnr) then
           return
             callback(
             string.format(
diff --git a/lua/conform/runner.lua b/lua/conform/runner.lua
index 7b3e468..a8ea203 100644
--- a/lua/conform/runner.lua
+++ b/lua/conform/runner.lua
@@ -467,14 +467,8 @@ M.format_async = function(bufnr, formatters, range, callback)
         return callback(err)
       end
       assert(output_lines)
-      local new_changedtick = vim.b[bufnr].changedtick
-      -- changedtick gets set to -1 when vim is exiting. We have an autocmd that should store it in
-      -- last_changedtick before it is set to -1.
-      if new_changedtick == -1 then
-        new_changedtick = vim.b[bufnr].last_changedtick or -1
-      end
       -- discard formatting if buffer has changed
-      if not vim.api.nvim_buf_is_valid(bufnr) or changedtick ~= new_changedtick then
+      if not vim.api.nvim_buf_is_valid(bufnr) or changedtick ~= util.buf_get_changedtick(bufnr) then
         callback({
           code = M.ERROR_CODE.CONCURRENT_MODIFICATION,
           message = string.format(
diff --git a/lua/conform/util.lua b/lua/conform/util.lua
index ec6af45..8a0073a 100644
--- a/lua/conform/util.lua
+++ b/lua/conform/util.lua
@@ -156,4 +156,20 @@ M.add_formatter_args = function(formatter, extra_args, opts)
   end
 end
 
+---@param bufnr integer
+---@return integer
+M.buf_get_changedtick = function(bufnr)
+  if not vim.api.nvim_buf_is_valid(bufnr) then
+    return -2
+  end
+  local changedtick = vim.b[bufnr].changedtick
+  -- changedtick gets set to -1 when vim is exiting. We have an autocmd that should store it in
+  -- last_changedtick before it is set to -1.
+  if changedtick == -1 then
+    return vim.b[bufnr].last_changedtick or -1
+  else
+    return changedtick
+  end
+end
+
 return M