Warn about misplaced or duplicated function/macro declarations

Doc strings, `declare` and `interactive` forms must appear in that
order and at most once each.  Complain if they don't, instead of
silently ignoring the problem (bug#55905).

* lisp/emacs-lisp/byte-run.el (byte-run--parse-body)
(byte-run--parse-declarations): New.
(defmacro, defun): Check for declaration well-formedness as
described above.  Clarify doc strings.  Refactor some common code.
* test/lisp/emacs-lisp/bytecomp-resources/fun-attr-warn.el:
* test/lisp/emacs-lisp/bytecomp-tests.el (bytecomp-fun-attr-warn):
New test.

test/lisp/emacs-lisp/bytecomp-resources/fun-attr-warn.el

@@ -0,0 +1,266 @@
+;;; -*- lexical-binding: t -*-
+
+;; Correct
+
+(defun faw-str-decl-code (x)
+  "something"
+  (declare (pure t))
+  (print x))
+
+(defun faw-doc-decl-code (x)
+  (:documentation "something")
+  (declare (pure t))
+  (print x))
+
+(defun faw-str-int-code (x)
+  "something"
+  (interactive "P")
+  (print x))
+
+(defun faw-doc-int-code (x)
+  (:documentation "something")
+  (interactive "P")
+  (print x))
+
+(defun faw-decl-int-code (x)
+  (declare (pure t))
+  (interactive "P")
+  (print x))
+
+(defun faw-str-decl-int-code (x)
+  "something"
+  (declare (pure t))
+  (interactive "P")
+  (print x))
+
+(defun faw-doc-decl-int-code (x)
+  (:documentation "something")
+  (declare (pure t))
+  (interactive "P")
+  (print x))
+
+
+;; Correct (last string is return value)
+
+(defun faw-str ()
+  "something")
+
+(defun faw-decl-str ()
+  (declare (pure t))
+  "something")
+
+(defun faw-decl-int-str ()
+  (declare (pure t))
+  (interactive)
+  "something")
+
+(defun faw-str-str ()
+  "something"
+  "something else")
+
+(defun faw-doc-str ()
+  (:documentation "something")
+  "something else")
+
+
+;; Incorrect (bad order)
+
+(defun faw-int-decl-code (x)
+  (interactive "P")
+  (declare (pure t))
+  (print x))
+
+(defun faw-int-str-code (x)
+  (interactive "P")
+  "something"
+  (print x))
+
+(defun faw-int-doc-code (x)
+  (interactive "P")
+  (:documentation "something")
+  (print x))
+
+(defun faw-decl-str-code (x)
+  (declare (pure t))
+  "something"
+  (print x))
+
+(defun faw-decl-doc-code (x)
+  (declare (pure t))
+  (:documentation "something")
+  (print x))
+
+(defun faw-str-int-decl-code (x)
+  "something"
+  (interactive "P")
+  (declare (pure t))
+  (print x))
+
+(defun faw-doc-int-decl-code (x)
+  (:documentation "something")
+  (interactive "P")
+  (declare (pure t))
+  (print x))
+
+(defun faw-int-str-decl-code (x)
+  (interactive "P")
+  "something"
+  (declare (pure t))
+  (print x))
+
+(defun faw-int-doc-decl-code (x)
+  (interactive "P")
+  (:documentation "something")
+  (declare (pure t))
+  (print x))
+
+(defun faw-int-decl-str-code (x)
+  (interactive "P")
+  (declare (pure t))
+  "something"
+  (print x))
+
+(defun faw-int-decl-doc-code (x)
+  (interactive "P")
+  (declare (pure t))
+  (:documentation "something")
+  (print x))
+
+(defun faw-decl-int-str-code (x)
+  (declare (pure t))
+  (interactive "P")
+  "something"
+  (print x))
+
+(defun faw-decl-int-doc-code (x)
+  (declare (pure t))
+  (interactive "P")
+  (:documentation "something")
+  (print x))
+
+(defun faw-decl-str-int-code (x)
+  (declare (pure t))
+  "something"
+  (interactive "P")
+  (print x))
+
+(defun faw-decl-doc-int-code (x)
+  (declare (pure t))
+  (:documentation "something")
+  (interactive "P")
+  (print x))
+
+
+;; Incorrect (duplication)
+
+(defun faw-str-str-decl-int-code (x)
+  "something"
+  "something else"
+  (declare (pure t))
+  (interactive "P")
+  (print x))
+
+(defun faw-str-doc-decl-int-code (x)
+  "something"
+  (:documentation "something else")
+  (declare (pure t))
+  (interactive "P")
+  (print x))
+
+(defun faw-doc-str-decl-int-code (x)
+  (:documentation "something")
+  "something else"
+  (declare (pure t))
+  (interactive "P")
+  (print x))
+
+(defun faw-doc-doc-decl-int-code (x)
+  (:documentation "something")
+  (:documentation "something else")
+  (declare (pure t))
+  (interactive "P")
+  (print x))
+
+(defun faw-str-decl-str-int-code (x)
+  "something"
+  (declare (pure t))
+  "something else"
+  (interactive "P")
+  (print x))
+
+(defun faw-doc-decl-str-int-code (x)
+  (:documentation "something")
+  (declare (pure t))
+  "something else"
+  (interactive "P")
+  (print x))
+
+(defun faw-str-decl-doc-int-code (x)
+  "something"
+  (declare (pure t))
+  (:documentation "something else")
+  (interactive "P")
+  (print x))
+
+(defun faw-doc-decl-doc-int-code (x)
+  (:documentation "something")
+  (declare (pure t))
+  (:documentation "something else")
+  (interactive "P")
+  (print x))
+
+(defun faw-str-decl-decl-int-code (x)
+  "something"
+  (declare (pure t))
+  (declare (indent 1))
+  (interactive "P")
+  (print x))
+
+(defun faw-doc-decl-decl-int-code (x)
+  (:documentation "something")
+  (declare (pure t))
+  (declare (indent 1))
+  (interactive "P")
+  (print x))
+
+(defun faw-str-decl-int-decl-code (x)
+  "something"
+  (declare (pure t))
+  (interactive "P")
+  (declare (indent 1))
+  (print x))
+
+(defun faw-doc-decl-int-decl-code (x)
+  (:documentation "something")
+  (declare (pure t))
+  (interactive "P")
+  (declare (indent 1))
+  (print x))
+
+(defun faw-str-decl-int-int-code (x)
+  "something"
+  (declare (pure t))
+  (interactive "P")
+  (interactive "p")
+  (print x))
+
+(defun faw-doc-decl-int-int-code (x)
+  (:documentation "something")
+  (declare (pure t))
+  (interactive "P")
+  (interactive "p")
+  (print x))
+
+(defun faw-str-int-decl-int-code (x)
+  "something"
+  (interactive "P")
+  (declare (pure t))
+  (interactive "p")
+  (print x))
+
+(defun faw-doc-int-decl-int-code (x)
+  (:documentation "something")
+  (interactive "P")
+  (declare (pure t))
+  (interactive "p")
+  (print x))

test/lisp/emacs-lisp/bytecomp-tests.el

@@ -1580,6 +1580,69 @@ EXPECTED-POINT BINDINGS (MODES \\='\\='(ruby-mode js-mode python-mode)) \
       (should (equal (get fname 'lisp-indent-function) 1))
       (should (equal (aref bc 4) "tata\n\n(fn X)")))))
 
+(ert-deftest bytecomp-fun-attr-warn ()
+  ;; Check that warnings are emitted when doc strings, `declare' and
+  ;; `interactive' forms don't come in the proper order, or more than once.
+  (let* ((filename "fun-attr-warn.el")
+         (el (ert-resource-file filename))
+         (elc (concat el "c"))
+         (text-quoting-style 'grave))
+    (with-current-buffer (get-buffer-create "*Compile-Log*")
+      (let ((inhibit-read-only t))
+        (erase-buffer))
+      (byte-compile-file el)
+      (let ((expected
+             '("70:4: Warning: `declare' after `interactive'"
+               "74:4: Warning: Doc string after `interactive'"
+               "79:4: Warning: Doc string after `interactive'"
+               "84:4: Warning: Doc string after `declare'"
+               "89:4: Warning: Doc string after `declare'"
+               "96:4: Warning: `declare' after `interactive'"
+               "102:4: Warning: `declare' after `interactive'"
+               "108:4: Warning: `declare' after `interactive'"
+               "106:4: Warning: Doc string after `interactive'"
+               "114:4: Warning: `declare' after `interactive'"
+               "112:4: Warning: Doc string after `interactive'"
+               "118:4: Warning: Doc string after `interactive'"
+               "119:4: Warning: `declare' after `interactive'"
+               "124:4: Warning: Doc string after `interactive'"
+               "125:4: Warning: `declare' after `interactive'"
+               "130:4: Warning: Doc string after `declare'"
+               "136:4: Warning: Doc string after `declare'"
+               "142:4: Warning: Doc string after `declare'"
+               "148:4: Warning: Doc string after `declare'"
+               "159:4: Warning: More than one doc string"
+               "165:4: Warning: More than one doc string"
+               "171:4: Warning: More than one doc string"
+               "178:4: Warning: More than one doc string"
+               "186:4: Warning: More than one doc string"
+               "192:4: Warning: More than one doc string"
+               "200:4: Warning: More than one doc string"
+               "206:4: Warning: More than one doc string"
+               "215:4: Warning: More than one `declare' form"
+               "222:4: Warning: More than one `declare' form"
+               "230:4: Warning: More than one `declare' form"
+               "237:4: Warning: More than one `declare' form"
+               "244:4: Warning: More than one `interactive' form"
+               "251:4: Warning: More than one `interactive' form"
+               "258:4: Warning: More than one `interactive' form"
+               "257:4: Warning: `declare' after `interactive'"
+               "265:4: Warning: More than one `interactive' form"
+               "264:4: Warning: `declare' after `interactive'")))
+        (goto-char (point-min))
+        (let ((actual nil))
+          (while (re-search-forward
+                  (rx bol (* (not ":")) ":"
+                      (group (+ digit) ":" (+ digit) ": Warning: "
+                             (or "More than one " (+ nonl) " form"
+                                 (: (+ nonl) " after " (+ nonl))))
+                      eol)
+                  nil t)
+            (push (match-string 1) actual))
+          (setq actual (nreverse actual))
+          (should (equal actual expected)))))))
+
+
 ;; Local Variables:
 ;; no-byte-compile: t
 ;; End: