undo: when adding text adds a magicline, an undo should remove both

This fixes http://savannah.gnu.org/bugs/?52523.

src/nano.c

@@ -1813,13 +1813,6 @@ void do_output(char *output, size_t output_len, bool allow_cntrls)
 	if (!allow_cntrls && is_ascii_cntrl_char(*(output + i -	char_len)))
 	    continue;
 
-	/* If we're adding to the magicline, create a new magicline. */
-	if (!ISSET(NO_NEWLINES) && openfile->filebot == openfile->current) {
-	    new_magicline();
-	    if (margin > 0)
-		refresh_needed = TRUE;
-	}
-
 	/* Make room for the new character and copy it into the line. */
 	openfile->current->data = charealloc(openfile->current->data,
 					current_len + char_len + 1);
@@ -1856,6 +1849,13 @@ void do_output(char *output, size_t output_len, bool allow_cntrls)
 	update_undo(ADD);
 #endif
 
+	/* If we've added text to the magicline, create a new magicline. */
+	if (openfile->filebot == openfile->current && !ISSET(NO_NEWLINES)) {
+	    new_magicline();
+	    if (margin > 0)
+		refresh_needed = TRUE;
+	}
+
 #ifdef ENABLE_WRAPPING
 	/* If text gets wrapped, the edit window needs a refresh. */
 	if (!ISSET(NO_WRAP) && do_wrap(openfile->current))

src/nano.h

@@ -607,9 +607,10 @@ enum
 /* Some extra flags for the undo function. */
 #define WAS_FINAL_BACKSPACE	(1<<1)
 #define WAS_WHOLE_LINE		(1<<2)
+#define WAS_FINAL_LINE		(1<<3)
 /* The flags for the mark need to be the highest. */
-#define MARK_WAS_SET		(1<<3)
-#define WAS_MARKED_FORWARD	(1<<4)
+#define MARK_WAS_SET		(1<<4)
+#define WAS_MARKED_FORWARD	(1<<5)
 #endif /* !NANO_TINY */
 
 /* The maximum number of entries displayed in the main shortcut list. */

src/text.c

@@ -734,6 +734,8 @@ void do_undo(void)
 	/* TRANSLATORS: The next twelve strings describe actions
 	 * that are undone or redone.  It are all nouns, not verbs. */
 	undidmsg = _("text add");
+	if (u->xflags == WAS_FINAL_LINE && !ISSET(NO_NEWLINES))
+	    remove_magicline();
 	data = charalloc(strlen(f->data) - strlen(u->strdata) + 1);
 	strncpy(data, f->data, u->begin);
 	strcpy(&data[u->begin], &f->data[u->begin + strlen(u->strdata)]);
@@ -907,6 +909,8 @@ void do_redo(void)
     switch (u->type) {
     case ADD:
 	redidmsg = _("text add");
+	if (u->xflags == WAS_FINAL_LINE && !ISSET(NO_NEWLINES))
+	    new_magicline();
 	data = charalloc(strlen(f->data) + strlen(u->strdata) + 1);
 	strncpy(data, f->data, u->begin);
 	strcpy(&data[u->begin], u->strdata);
@@ -1272,6 +1276,9 @@ void add_undo(undo_type action)
     /* We need to start copying data into the undo buffer
      * or we won't be able to restore it later. */
     case ADD:
+	/* If a new magic line will be added, an undo should remove it. */
+	if (openfile->current == openfile->filebot && openfile->current_x == 0)
+	    u->xflags = WAS_FINAL_LINE;
 	u->wassize--;
 	break;
     case BACK: