BUG + FIX. Spurious "might not be defined at runtime" from byte-compile-file

[Alan Mackenzie]

Hi, Emacs!

Evaluate the following:

(defun foo ()
  (bar))
(byte-compile 'foo)
(defun bar ())
(byte-compile 'bar)

Get a cup of coffee, go for a twenty mile run, come back and do some
furious hacking.

Then do M-x byte-compile-file jrandom.el.  You get the spurious warning:

  ** The function `bar' might not be defined at runtime.

This happens because the (byte-compile 'foo) form (correctly) flags 'bar
as an unknown function, recording it in
byte-compile-unresolved-functions.  The subsequent byte-compile-file
initialises this variable AFTER doing the compilation rather than before
- hence the silly warning.

It seems to me this state of affairs was probably caused by the sloppy
doc-string for the variable - it doesn't give any context for when its
contents are gathered and used, hence hackers were (subconsciously)
scared to initialise it properly, fearing they might discard important
info.  So I've amended the doc-string too.

Should I commit this fix?



2006-05-23  Alan Mackenzie  <address@hidden>

        * emacs-lisp/bytecomp.el (byte-compile-from-buffer): initialize
        byte-compile-unresolved-functions before doing a compilation
        rather than afterwards.  Amend the variable's doc-string.


Index: bytecomp.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/emacs-lisp/bytecomp.el,v
retrieving revision 2.183
diff -c -r2.183 bytecomp.el
*** bytecomp.el 11 Apr 2006 17:58:49 -0000      2.183
--- bytecomp.el 23 May 2006 09:56:18 -0000
***************
*** 453,459 ****
  
  (defvar byte-compile-unresolved-functions nil
    "Alist of undefined functions to which calls have been compiled.
! Used for warnings when the function is not known to be defined or is later
  defined with incorrect args.")
  
  (defvar byte-compile-noruntime-functions nil
--- 453,460 ----
  
  (defvar byte-compile-unresolved-functions nil
    "Alist of undefined functions to which calls have been compiled.
! This variable is only significant whilst compiling an entire buffer.
! Used for warnings when a function is not known to be defined or is later
  defined with incorrect args.")
  
  (defvar byte-compile-noruntime-functions nil
***************
*** 1821,1826 ****
--- 1822,1832 ----
        (save-excursion
        (set-buffer inbuffer)
        (goto-char 1)
+       ;; Should we always do this?  When calling multiple files, it
+       ;; would be useful to delay this warning until all have been
+       ;; compiled.  A: Yes!  b-c-u-f might contain dross from a
+       ;; previous byte-compile.
+       (setq byte-compile-unresolved-functions nil)
  
        ;; Compile the forms from the input buffer.
        (while (progn
***************
*** 1837,1847 ****
        ;; Make warnings about unresolved functions
        ;; give the end of the file as their position.
        (setq byte-compile-last-position (point-max))
!       (byte-compile-warn-about-unresolved-functions)
!       ;; Should we always do this?  When calling multiple files, it
!       ;; would be useful to delay this warning until all have
!       ;; been compiled.
!       (setq byte-compile-unresolved-functions nil))
        ;; Fix up the header at the front of the output
        ;; if the buffer contains multibyte characters.
        (and filename (byte-compile-fix-header filename inbuffer outbuffer))))
--- 1843,1849 ----
        ;; Make warnings about unresolved functions
        ;; give the end of the file as their position.
        (setq byte-compile-last-position (point-max))
!       (byte-compile-warn-about-unresolved-functions))
        ;; Fix up the header at the front of the output
        ;; if the buffer contains multibyte characters.
        (and filename (byte-compile-fix-header filename inbuffer outbuffer))))



-- 
Alan.