In order to make `project-recompile' symmetric to `recompile' it should
be autoloaded and it should run in the project root. This makes it
possible to call `project-recompile' directly without calling `compile'
first.

    ;;;###autoload
    (defun project-recompile (&optional edit-command)
      "Run `recompile' with appropriate buffer."
      (declare (interactive-only recompile))
      (interactive "P")
      (let ((default-directory (project-root (project-current t)))
            (compilation-buffer-name-function
             (or project-compilation-buffer-name-function
                 compilation-buffer-name-function)))
        (recompile edit-command)))

This change also resolves the comment in project-recompile:

    ;; Should we error instead?  When there's no
    ;; project-specific naming, there is no point in using
    ;; this command.