Avoid recursive byte-compile-files fighting over input/output buffers

* lisp/emacs-lisp/bytecomp.el (byte-compile-level): New.
(byte-compile-file, byte-compile-from-buffer):
Use separate input/output buffers for each level of recursive
byte-compile-file calls.

Fixes: debbugs:13787

1 files changed, 18 insertions, 3 deletions

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 280a1bbc2dd..f5861550c9a 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -1675,6 +1675,9 @@ If compilation is needed, this functions returns the result of
 	(load (if (file-exists-p dest) dest filename)))
       'no-byte-compile)))
 
+(defvar byte-compile-level 0		; bug#13787
+  "Depth of a recursive byte compilation.")
+
 ;;;###autoload
 (defun byte-compile-file (filename &optional load)
   "Compile a file of Lisp code named FILENAME into a file of byte code.
@@ -1717,7 +1720,13 @@ The value is non-nil if there were no errors, nil if errors."
     (setq target-file (byte-compile-dest-file filename))
     (setq byte-compile-dest-file target-file)
     (with-current-buffer
-        (setq input-buffer (get-buffer-create " *Compiler Input*"))
+	;; It would be cleaner to use a temp buffer, but if there was
+	;; an error, we leave this buffer around for diagnostics.
+	;; Its name is documented in the lispref.
+	(setq input-buffer (get-buffer-create
+			    (concat " *Compiler Input*"
+				    (if (zerop byte-compile-level) ""
+				      (format "-%s" byte-compile-level)))))
       (erase-buffer)
       (setq buffer-file-coding-system nil)
       ;; Always compile an Emacs Lisp file as multibyte
@@ -1770,12 +1779,15 @@ The value is non-nil if there were no errors, nil if errors."
       (when byte-compile-verbose
 	(message "Compiling %s..." filename))
       (setq byte-compiler-error-flag nil)
+      (setq byte-compile-level (1+ byte-compile-level))
       ;; It is important that input-buffer not be current at this call,
       ;; so that the value of point set in input-buffer
       ;; within byte-compile-from-buffer lingers in that buffer.
       (setq output-buffer
 	    (save-current-buffer
-	      (byte-compile-from-buffer input-buffer)))
+	      (unwind-protect
+		  (byte-compile-from-buffer input-buffer)
+		(setq byte-compile-level (1- byte-compile-level)))))
       (if byte-compiler-error-flag
 	  nil
 	(when byte-compile-verbose
@@ -1881,7 +1893,10 @@ With argument ARG, insert value in current buffer after the form."
     (byte-compile-close-variables
      (with-current-buffer
          (setq byte-compile--outbuffer
-               (get-buffer-create " *Compiler Output*"))
+               (get-buffer-create
+                (concat " *Compiler Output*"
+                        (if (<= byte-compile-level 1) ""
+                          (format "-%s" (1- byte-compile-level))))))
        (set-buffer-multibyte t)
        (erase-buffer)
        ;;	 (emacs-lisp-mode)