bug#53024: 29.0.50; Wishlist: Byte-compile loaddefs.el?

[Lars Ingebrigtsen <larsi@gnus.org>]

With the following, Emacs builds successfully.  The problem is that we
need to generate the loaddefs files before compile-main (so that it
picks up the .el files for compilation), but we do this after we've
built Emacs, so a change that updates loaddefs.el will first compile the
.elc file, and then the next "make" will rebuild src/emacs, which is
backwards.

But I'm unable to follow the logic completely in the relevant Makefiles.
I've tried a number of things here, but I seem to be unable to make the
src/Makefile depend on the lisp/loaddefs.elc file in any sensible way --
I either end up with generating the .elc file twice or none at all,
which is frustrating.

diff --git a/lisp/Makefile.in b/lisp/Makefile.in
index 9516f2fc36..8f08195df8 100644
--- a/lisp/Makefile.in
+++ b/lisp/Makefile.in
@@ -196,13 +196,16 @@ org-manuals:
 # from ../src rules, but that doesn't seem possible due to the various
 # non-trivial dependencies.
 
-# We make $(lisp)/loaddefs.el a dependency of .PHONY to cause Make to
+# We make autoloads a dependency of .PHONY to cause Make to
 # ignore its time stamp.  That's because the real dependencies of
 # loaddefs.el aren't known to Make, they are implemented in
 # loaddefs-generate--emacs-batch.
+autoloads .PHONY:
+	$(AM_V_GEN)$(emacs) \
+            -l $(lisp)/emacs-lisp/loaddefs-gen.elc \
+	    -f loaddefs-generate--emacs-batch ${SUBDIRS_ALMOST}
 
-autoloads .PHONY: $(lisp)/loaddefs.el
-$(lisp)/loaddefs.el: gen-lisp $(LOADDEFS) $(lisp)/emacs-lisp/loaddefs-gen.elc
+$(lisp)/loaddefs.el: $(LOADDEFS) $(lisp)/emacs-lisp/loaddefs-gen.elc
 	$(AM_V_GEN)$(emacs) \
             -l $(lisp)/emacs-lisp/loaddefs-gen.elc \
 	    -f loaddefs-generate--emacs-batch ${SUBDIRS_ALMOST}
diff --git a/lisp/emacs-lisp/loaddefs-gen.el b/lisp/emacs-lisp/loaddefs-gen.el
index 261e44aece..830799ec36 100644
--- a/lisp/emacs-lisp/loaddefs-gen.el
+++ b/lisp/emacs-lisp/loaddefs-gen.el
@@ -459,7 +459,7 @@ loaddefs-generate--compute-prefixes
             (push name prefs)))))
     (loaddefs-generate--make-prefixes prefs load-name)))
 
-(defun loaddefs-generate--rubric (file &optional type feature)
+(defun loaddefs-generate--rubric (file &optional type feature compile)
   "Return a string giving the appropriate autoload rubric for FILE.
 TYPE (default \"autoloads\") is a string stating the type of
 information contained in FILE.  TYPE \"package\" acts like the default,
@@ -467,7 +467,9 @@ loaddefs-generate--rubric
 
 If FEATURE is non-nil, FILE will provide a feature.  FEATURE may
 be a string naming the feature, otherwise it will be based on
-FILE's name."
+FILE's name.
+
+If COMPILE, don't include a \"don't compile\" cookie."
   (let ((lp (and (equal type "package") (setq type "autoloads"))))
     (with-temp-buffer
       (generate-lisp-file-heading
@@ -481,6 +483,7 @@ loaddefs-generate--rubric
       (insert "\f\n;;; End of scraped data\n\n")
       (generate-lisp-file-trailer
        file :provide (and (stringp feature) feature)
+       :compile compile
        :inhibit-provide (not feature))
       (buffer-string))))
 
@@ -585,7 +588,8 @@ loaddefs-generate
           (with-temp-buffer
             (if (and updating (file-exists-p loaddefs-file))
                 (insert-file-contents loaddefs-file)
-              (insert (loaddefs-generate--rubric loaddefs-file nil t))
+              (insert (loaddefs-generate--rubric
+                       loaddefs-file nil t include-package-version))
               (search-backward "\f")
               (when extra-data
                 (insert extra-data)
diff --git a/lisp/loadup.el b/lisp/loadup.el
index 21a87dbd77..a65c1724ae 100644
--- a/lisp/loadup.el
+++ b/lisp/loadup.el
@@ -185,9 +185,10 @@
 ;; should be updated by overwriting it with an up-to-date copy of
 ;; loaddefs.el that is not corrupted by local changes.
 ;; admin/update_autogen can be used to update ldefs-boot.el periodically.
-(condition-case nil (load "loaddefs.el")
-  ;; In case loaddefs hasn't been generated yet.
-  (file-error (load "ldefs-boot.el")))
+(condition-case nil
+    (load "loaddefs")
+  (file-error
+   (load "ldefs-boot.el")))
 
 (let ((new (make-hash-table :test #'equal)))
   ;; Now that loaddefs has populated definition-prefixes, purify its contents.
diff --git a/src/Makefile.in b/src/Makefile.in
index 7d15b7afd5..feb809ea10 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -652,13 +652,11 @@ $(pdmp):
 ## for the first time, this prevents any variation between configurations
 ## in the contents of the DOC file.
 ##
-$(etc)/DOC: $(libsrc)/make-docfile$(EXEEXT) $(doc_obj) $(lispsource)/loaddefs.el
+$(etc)/DOC: $(libsrc)/make-docfile$(EXEEXT) $(doc_obj)
 	$(AM_V_GEN)$(MKDIR_P) $(etc)
 	$(AM_V_at)rm -f $(etc)/DOC
 	$(AM_V_at)$(libsrc)/make-docfile -d $(srcdir) \
 	  $(SOME_MACHINE_OBJECTS) $(doc_obj) > $(etc)/DOC
-	$(AM_V_at)$(libsrc)/make-docfile -a $(etc)/DOC -d $(lispsource) \
-	  loaddefs.el
 
 $(libsrc)/make-docfile$(EXEEXT) $(libsrc)/make-fingerprint$(EXEEXT): \
   $(lib)/libgnu.a