elisp 错误“错误类型参数：sequencep, t”是什么意思？意思是？

Question

我正在尝试字节编译 cc-mode 5.31。 3 使用 emacs 23.1.1 如下：

$ emacs -batch --no-site-file -q -f batch-byte-compile *.el

但是其中两个文件无法编译（除了大量警告之外）：

In c-init-language-vars-for:
cc-mode.el:168:10:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:168:10:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:162:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:162:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:163:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:163:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:164:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:164:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:165:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:165:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:166:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:166:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:167:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:167:53:Warning: Function `mapcan' from cl package called at runtime
cc-mode.el:562:4:Error: Wrong type argument: sequencep, t

In c-make-styles-buffer-local:
cc-styles.el:634:6:Warning: `mapcar' called for effect; use `mapc' or `dolist'
    instead
cc-styles.el:636:9:Error: Wrong type argument: sequencep, t

这两个错误是什么意思，如何修复它们？

cc-mode.el 的第 562 行是这样的：

  (c-update-modeline)

其中 c-update-modeline 是 cc-cmds.el 中定义的不带参数的函数。该函数的 cc-styles.el 部分的第 636 行：

(defun c-make-styles-buffer-local (&optional this-buf-only-p)
  "Make all CC Mode style variables buffer local.
If `this-buf-only-p' is non-nil, the style variables will be made
buffer local only in the current buffer.  Otherwise they'll be made
permanently buffer local in any buffer that changes their values.

The buffer localness of the style variables are normally controlled
with the variable `c-style-variables-are-local-p', so there's seldom
any reason to call this function directly."

  ;; style variables
  (let ((func (if this-buf-only-p
          'make-local-variable
        'make-variable-buffer-local))
    (varsyms (cons 'c-indentation-style (copy-alist c-style-variables))))
    (delq 'c-special-indent-hook varsyms)
    (mapcar func varsyms)
    ;; Hooks must be handled specially
    (if this-buf-only-p    ;;;;;;;;; LINE 636 ;;;;;;;;;;;;;;;;;;
        (make-local-hook 'c-special-indent-hook)
      (make-variable-buffer-local 'c-special-indent-hook)
      (setq c-style-variables-are-local-p t))
    ))

这些错误消息没有意义。我已经随 emacs 安装了不同版本的 cc-mode，这一事实是否会影响此问题？如何重新编译 cc-mode？

Answer 1

该错误的含义是，需要 sequence 的函数却收到了 t；该消息告诉您 t 不满足谓词 sequencep。

例如，尝试评估 (length t) ，您将在 *Backtrace* 中看到（假设您将 debug-on-error 设置为 t)：

Debugger entered--Lisp error: (wrong-type-argument sequencep t)
  length(t)
  eval((length t) nil)

您看到的消息是由 error-message-string 生成的：

(condition-case e (length t)
  (error (error-message-string e)))
==> "Wrong type argument: sequencep, t"

Answer 2

我仍然对这些错误消息感到困惑，但答案是 cc-mode 5.31.3 相当旧，无法使用 emacs 23 进行编译（出于好奇，我试图编译 cc-mode）。 emacs 23 附带了 cc-mode 的更新版本，版本 5.31.7 - 运行交互式命令 c-version 来获取您正在使用的 cc-mode 版本。

对于那些想要重新编译 cc-mode 的人（而不是使用 emacs 附带的已编译的 cc-mode.elc），您应该使用从 匿名 CVS