在.dir-locals中设置flycheck-clang-include-path

Question

尝试设置flycheck-clang- include -path而不需要包含项目的完整路径使用projectile包含目录，但我得到错误...所以这是可行的：

((nil . (
     (company-clang-arguments . (
                     "/home/user/Downloads/project/headers"
                     "/home/user/Downloads/project/source/mon"
                     ))
         (flycheck-clang-include-path . (
                     "/home/user/Downloads/project/headers"
                     "/home/user/Downloads/project/source/mon"
                     ))
     )))

但这不是：

((nil . (
     (company-clang-arguments . (
                     (concat "-I" (projectile-project-root) "headers")
                     (concat "-I" (projectile-project-root) "source/mon")
                     ))
         (flycheck-clang-include-path . (
                     (concat (projectile-project-root) "headers")
                     (concat (projectile-project-root) "source/mon")
                     ))
     )))

报告的错误：

flycheck-substitute-argument: Value ((concat (projectile-project-root) "headers")) of flycheck-clang-include-path for option "-I" is not a list of strings