From c593fc94f2289d4bdcb61835eaf11b0fe393a0f5 Mon Sep 17 00:00:00 2001
From: Augusto Stoffel <arstoffel@gmail.com>
Date: Thu, 8 Dec 2022 21:05:10 +0100
Subject: [PATCH 1/2] Introduce 'compilation-aside' text property

It is meant to mark parts of compilation buffers which do not
correspond to process output.

* lisp/progmodes/compile.el (compilation-insert-aside):  New function.
(compilation-start, compilation-handle-exit): Use it.
(compilation--ensure-parse) Rely on 'compilation-aside' property
instead of 'compilation-header-end'
---
 lisp/progmodes/compile.el | 35 +++++++++++++++++++++--------------
 1 file changed, 21 insertions(+), 14 deletions(-)

diff --git a/lisp/progmodes/compile.el b/lisp/progmodes/compile.el
index e8ada9388e..2d22501017 100644
--- a/lisp/progmodes/compile.el
+++ b/lisp/progmodes/compile.el
@@ -1675,7 +1675,7 @@ compilation--ensure-parse
             (set-marker (make-marker)
                         (save-excursion
                           (goto-char (point-min))
-                          (text-property-search-forward 'compilation-header-end)
+                          (text-property-search-forward 'compilation-aside)
                           ;; If we have no end marker, this will be
                           ;; `point-min' still.
                           (point)))))
@@ -1823,6 +1823,14 @@ compilation--update-in-progress-mode-line
   ;; buffers when it changes from nil to non-nil or vice-versa.
   (unless compilation-in-progress (force-mode-line-update t)))
 
+(defun compilation-insert-aside (&rest args)
+  "Insert ARGS at point, adding the `compilation-aside' text property.
+This property is used to distinguish output of the compilation
+process from additional information inserted by Emacs."
+  (let ((start (point)))
+    (apply #'insert args)
+    (put-text-property start (point) 'compilation-aside t)))
+
 ;;;###autoload
 (defun compilation-start (command &optional mode name-function highlight-regexp
                                   continue)
@@ -1944,17 +1952,16 @@ compilation-start
             (setq-local compilation-auto-jump-to-next t))
         (when (zerop (buffer-size))
 	  ;; Output a mode setter, for saving and later reloading this buffer.
-	  (insert "-*- mode: " name-of-mode
-		  "; default-directory: "
-                  (prin1-to-string (abbreviate-file-name default-directory))
-		  " -*-\n"))
-        (insert (format "%s started at %s\n\n"
-			mode-name
-			(substring (current-time-string) 0 19))
-		command "\n")
-        ;; Mark the end of the header so that we don't interpret
-        ;; anything in it as an error.
-        (put-text-property (1- (point)) (point) 'compilation-header-end t)
+	  (compilation-insert-aside
+           "-*- mode: " name-of-mode
+           "; default-directory: "
+           (prin1-to-string (abbreviate-file-name default-directory))
+	   " -*-\n"))
+        (compilation-insert-aside
+         (format "%s started at %s\n\n"
+                 mode-name
+		 (substring (current-time-string) 0 19))
+	 command "\n")
 	(setq thisdir default-directory))
       (set-buffer-modified-p nil))
     ;; Pop up the compilation buffer.
@@ -2436,13 +2443,13 @@ compilation-handle-exit
 	(cur-buffer (current-buffer)))
     ;; Record where we put the message, so we can ignore it later on.
     (goto-char omax)
-    (insert ?\n mode-name " " (car status))
+    (compilation-insert-aside ?\n mode-name " " (car status))
     (if (and (numberp compilation-window-height)
 	     (zerop compilation-window-height))
 	(message "%s" (cdr status)))
     (if (bolp)
 	(forward-char -1))
-    (insert " at " (substring (current-time-string) 0 19))
+    (compilation-insert-aside " at " (substring (current-time-string) 0 19))
     (goto-char (point-max))
     ;; Prevent that message from being recognized as a compilation error.
     (add-text-properties omax (point)
-- 
2.38.1