feat: support nested directory for tmpfile_format

Author: PeterCardenas

lua/conform/runner.lua

@@ -370,13 +370,48 @@ 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)
+    -- ctx.filename can contain directories relative to ctx.dirname
+    -- Thus, we check which directories relative to ctx.dirname exist and remove
+    -- the deepest one that does not exist.
+    local res = vim
+      .iter(
+        vim.split(
+          assert(
+            vim.fs.relpath(ctx.dirname, ctx.filename),
+            "filename " .. ctx.filename .. " is not a child of dirname " .. ctx.dirname
+          ),
+          "/",
+          { plain = true }
+        )
+      )
+      :rskip(1)
+      :fold(
+        { path = ctx.dirname, found_not_exists = false },
+        ---@param path_part string
+        function(acc, path_part)
+          local new_path = vim.fs.joinpath(acc.path, path_part)
+          if not acc.found_not_exists then
+            acc.path = new_path
+          end
+          acc.found_not_exists = vim.fn.isdirectory(new_path) == 0
+          return acc
+        end
+      )
+    local dir_to_remove = res.path
+    local can_remove = res.found_not_exists
+
     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)
+      -- If all directories relative to ctx.dirname exist, there are no directories to remove.
+      if can_remove then
+        log.debug("Cleaning up temp dir %s", dir_to_remove)
+        vim.fs.rm(dir_to_remove, { recursive = true })
+      end
     end)
   end