(loaddefs-generate--emacs-batch): Chdir to lisp-directory

Chdir once and for all at the beginning to simplify the code.
Eliminate some redundant `expand-file-name`s and fix a broken use
of `expand-file-name` where we passed a list as second arg.

* lisp/emacs-lisp/loaddefs-gen.el (loaddefs-generate): Rename DIR to
DIRS, to clarify that it can be a list.  Use `ensure-list`.
Don't pass DIR(S) directly to `expand-file-name`.
Remove redundant `expand-file-name`.
(loaddefs-generate--excluded-files): Add sanity checks.
Return relative file names since `loaddefs-generate` will make them
absolute anyway.  Simplify.
(loaddefs-generate--emacs-batch): Chdir to `lisp-directory` and
simplify the rest accordingly.

lisp/emacs-lisp/loaddefs-gen.el

@@ -593,7 +593,7 @@ If COMPILE, don't include a \"don't compile\" cookie."
       (buffer-string))))
 
 ;;;###autoload
-(defun loaddefs-generate (dir output-file &optional excluded-files
+(defun loaddefs-generate (dirs output-file &optional excluded-files
                               extra-data include-package-version
                               generate-full)
   "Generate loaddefs files for Lisp files in one or more directories given by DIR.
@@ -632,13 +632,18 @@ instead of just updating them with the new/changed autoloads."
 		       (mapcar (lambda (d)
 				 (directory-files (expand-file-name d)
                                                   t files-re))
-			       (if (consp dir) dir (list dir)))))
+			       (ensure-list dirs))))
          (updating (and (file-exists-p output-file) (not generate-full)))
          (defs nil))
     ;; Allow the excluded files to be relative.
-    (setq excluded-files
+    ;; We used to do (expand-file-name file dir), which strangely enough
-          (mapcar (lambda (file) (expand-file-name file dir))
+    ;; doesn't signal an error when DIR is a list but does something weird
-                  excluded-files))
+    ;; instead, so let's preserve the old behavior when DIR is a string,
+    ;; even tho it's different from what we do when it's a list.
+    (let ((basedir (if (stringp dirs) dirs)))
+      (setq excluded-files
+            (mapcar (lambda (file) (expand-file-name file basedir))
+                    excluded-files)))
 
     ;; Collect all the autoload data.
     (let ((progress (make-progress-reporter
@@ -657,7 +662,7 @@ instead of just updating them with the new/changed autoloads."
                                 (file-attributes file))))
           ;; If we're scanning for package versions, we want to look
           ;; at the file even if it's excluded.
-          (let* ((excluded (member (expand-file-name file dir) excluded-files))
+          (let* ((excluded (member file excluded-files))
                  (package-data
                   (and include-package-version (if excluded 'only t))))
             (when (or package-data (not excluded))
@@ -724,7 +729,7 @@ instead of just updating them with the new/changed autoloads."
           (unless (equal (buffer-hash) hash)
             (write-region (point-min) (point-max) loaddefs-file nil 'silent)
             (byte-compile-info
-             (file-relative-name loaddefs-file (car (ensure-list dir)))
+             (file-relative-name loaddefs-file (car (ensure-list dirs)))
              t "GEN")))))
 
     ;; If processing files without any autoloads, the above loop will
@@ -776,19 +781,21 @@ instead of just updating them with the new/changed autoloads."
   ;; Exclude those files that are preloaded on ALL platforms.
   ;; These are the ones in loadup.el where "(load" is at the start
   ;; of the line (crude, but it works).
-  (let ((default-directory (file-name-directory lisp-directory))
+  (unless (equal default-directory (file-name-as-directory lisp-directory))
-        (excludes nil)
+    (error "PWD is not set as expected: %S" default-directory))
-	file)
+  (let ((excludes nil))
     (with-temp-buffer
       (insert-file-contents "loadup.el")
+      (when (= (point-min) (point-max)) (error "Can't find loadup.el"))
       (while (re-search-forward "^(load \"\\([^\"]+\\)\"" nil t)
-	(setq file (match-string 1))
+	(let ((file (match-string 1)))
-	(or (string-match "\\.el\\'" file)
+	  (unless (string-match "\\`site-" file)
-	    (setq file (format "%s.el" file)))
+	    (push (if (string-match "\\.el\\'" file)
-	(or (string-match "\\`site-" file)
+	              file
-	    (push (expand-file-name file) excludes))))
+	            (format "%s.el" file))
+	          excludes)))))
     ;; Don't scan ldefs-boot.el, either.
-    (cons (expand-file-name "ldefs-boot.el") excludes)))
+    (cons "ldefs-boot.el" excludes)))
 
 ;;;###autoload
 (defun loaddefs-generate-batch ()
@@ -806,8 +813,12 @@ use."
   "Generate the loaddefs for the Emacs build.
 This is like `loaddefs-generate-batch', but has some specific
 rules for built-in packages and excluded files."
-  (let ((args command-line-args-left)
+  (let* ((args command-line-args-left)
-        (output-file (expand-file-name "loaddefs.el" lisp-directory)))
+         ;; We're run from $BUILDDIR/lisp but all the .el(c) files reside
+         ;; (and are generated) in `lisp-directory' which is in $SRCDIR,
+         ;; so go there and don't look back.
+         (default-directory lisp-directory)
+         (output-file (expand-file-name "loaddefs.el")))
     (setq command-line-args-left nil)
     (loaddefs-generate
      args output-file
@@ -817,12 +828,12 @@ rules for built-in packages and excluded files."
      ;; updated.
      (file-newer-than-file-p
       (expand-file-name "emacs-lisp/loaddefs-gen.el" lisp-directory)
-      output-file)))
+      output-file))
-  (let ((lisp-mode-autoload-regexp
+    (let ((lisp-mode-autoload-regexp
-         "^;;;###\\(\\(noexist\\)-\\)?\\(theme-autoload\\)"))
+           "^;;;###\\(\\(noexist\\)-\\)?\\(theme-autoload\\)"))
       (loaddefs-generate
-       (expand-file-name "../etc/themes/" lisp-directory)
+       (expand-file-name "../etc/themes/")
-       (expand-file-name "theme-loaddefs.el" lisp-directory))))
+       (expand-file-name "theme-loaddefs.el")))))
 
 ;;;###autoload (load "theme-loaddefs.el" t)