Derive SWANK protocol version from slime-version

The main goal here is to remove the dependency on the ChangeLog
file. This should work well enough if releases are frequent.

Makefile

@@ -36,7 +36,7 @@ SELECTOR  -- selector for ERT tests ($(SELECTOR))\n"
 
 # Compilation
 #
-slime.elc: slime.el ChangeLog lib/hyperspec.elc
+slime.elc: slime.el lib/hyperspec.elc
 
 %.elc: %.el
 	$(EMACS) -Q $(LOAD_PATH) --batch -f batch-byte-compile $<

slime.el

@@ -138,32 +138,8 @@ CONTRIBS is a list of contrib packages to load. If `nil', use
   (set (make-local-variable 'lisp-indent-function)
        'common-lisp-indent-function))
 
-(eval-and-compile
-  (defun slime--changelog-file-name ()
-    (expand-file-name "ChangeLog"
-                      (if (and (boundp 'byte-compile-current-file)
-                               byte-compile-current-file)
-                          (file-name-directory byte-compile-current-file)
-                          slime-path)))
-
-  (defun slime-changelog-date (&optional interactivep)
-    "Return the datestring of the latest entry in the ChangeLog file.
-Return nil if the ChangeLog file cannot be found."
-    (interactive "p")
-    (let ((changelog (slime--changelog-file-name))
-          (date nil))
-      (when (file-exists-p changelog)
-        (with-temp-buffer
-          (insert-file-contents-literally changelog nil 0 100)
-          (goto-char (point-min))
-          (setq date (symbol-name (read (current-buffer))))))
-      (when interactivep
-        (message "Slime ChangeLog dates %s." date))
-      date)))
-
 (defvar slime-protocol-version nil)
-(setq slime-protocol-version
-      (eval-when-compile (slime-changelog-date)))
+(setq slime-protocol-version slime-version)
 
 
 ;;;; Customize groups

swank-loader.lisp

@@ -133,12 +133,19 @@ operating system, and hardware architecture."
   "Returns true if NEW-FILE is newer than OLD-FILE."
   (> (file-write-date new-file) (file-write-date old-file)))
 
+(defun string-starts-with (string prefix)
+  (string-equal string prefix :end1 (min (length string) (length prefix))))
+
 (defun slime-version-string ()
   "Return a string identifying the SLIME version.
 Return nil if nothing appropriate is available."
-  (with-open-file (s (merge-pathnames "ChangeLog" *source-directory*)
+  (with-open-file (s (merge-pathnames "slime.el" *source-directory*)
                      :if-does-not-exist nil)
-    (and s (symbol-name (read s)))))
+    (loop with prefix = ";; Version: "
+          for line = (read-line s nil :eof)
+          until (eq line :eof)
+          when (string-starts-with line prefix)
+            return (subseq line (length prefix)))))
 
 (defun default-fasl-dir ()
   (merge-pathnames
@@ -300,9 +307,6 @@ If LOAD is true, load the fasl file."
     (eval `(pushnew 'compile-contribs ,(q "swank::*after-init-hook*"))))
   (funcall (q "swank::init")))
 
-(defun string-starts-with (string prefix)
-  (string-equal string prefix :end1 (min (length string) (length prefix))))
-
 (defun list-swank-packages ()
   (remove-if-not (lambda (package)
                    (let ((name (package-name package)))