feat: support nested directory for tmpfile_format

lua/conform/runner.lua

@@ -293,6 +293,10 @@ end
 ---@type table<string, boolean>
 local last_run_errored = {}
 
+---Set of temporary directories to remove after formatting
+---@type string[]
+local temp_dirs = {}
+
 ---@param bufnr integer
 ---@param formatter conform.FormatterInfo
 ---@param config conform.FormatterConfig
@@ -370,13 +374,41 @@ local function run_formatter(bufnr, formatter, config, ctx, input_lines, opts, c
 
   if not config.stdin then
     log.debug("Creating temp file %s", ctx.filename)
+    local current_parent_dir = vim.fs.dirname(ctx.filename)
+    -- Keep track of the current parent directories created, so we can delete them later
+    while
+      current_parent_dir
+      and current_parent_dir ~= ctx.dirname
+      and vim.fn.isdirectory(current_parent_dir) == 0
+    do
+      temp_dirs[#temp_dirs + 1] = current_parent_dir
+      current_parent_dir = vim.fs.dirname(current_parent_dir)
+    end
+
     vim.fn.mkdir(vim.fs.dirname(ctx.filename), "p")
     local fd = assert(uv.fs_open(ctx.filename, "w", 448)) -- 0700
     uv.fs_write(fd, buffer_text)
     uv.fs_close(fd)
     callback = util.wrap_callback(callback, function()
       log.debug("Cleaning up temp file %s", ctx.filename)
       uv.fs_unlink(ctx.filename)
+      local temp_dir_idx = 1
+      while temp_dir_idx <= #temp_dirs do
+        local temp_dir_to_remove = temp_dirs[temp_dir_idx]
+        log.debug("Cleaning up temp dir %s", temp_dir_to_remove)
+        local success, err_name, err_msg = uv.fs_rmdir(temp_dir_to_remove)
+        if not success then
+          log.debug(
+            "Failed to remove temp directory %s: %s: %s",
+            temp_dir_to_remove,
+            err_name,
+            err_msg
+          )
+          temp_dir_idx = temp_dir_idx + 1
+        else
+          table.remove(temp_dirs, temp_dir_idx)
+        end
+      end
     end)
   end