From d78000728351986b0083013728dc3ef366112c0b Mon Sep 17 00:00:00 2001
From: Basil L. Contovounesios
Date: Wed, 18 Mar 2026 12:42:28 +0100
Subject: Add predicate for initial_terminal

This introduces the predicate frame-initial-p, which uses
struct frame.output_method or struct terminal.type to detect
initial_terminal without relying on its name (bug#80629).
For some prior discussion, see:
https://lists.gnu.org/r/emacs-devel/2019-12/msg00480.html
https://lists.gnu.org/r/emacs-devel/2020-01/msg00120.html

* doc/lispref/frames.texi (Frames): Document frame-initial-p.
(Finding All Frames): Fix grammar.
* etc/NEWS (Lisp Changes in Emacs 31.1): Announce frame-initial-p.
* lisp/desktop.el (desktop--check-dont-save):
* lisp/emacs-lisp/debug.el (debug):
* lisp/frameset.el (frameset-restore):
* lisp/menu-bar.el (menu-bar-update-buffers):
* lisp/xt-mouse.el (turn-on-xterm-mouse-tracking-on-terminal):
Use frame-initial-p instead of checking the "initial_terminal" name.
* lisp/emacs-lisp/byte-opt.el: Mark frame-initial-p as error-free.

* src/pgtkterm.c (pgtk_focus_changed): Use IS_DAEMON in place of
Fdaemonp, thus also accepting a named daemon session.
* src/terminal.c (decode_tty_terminal): Clarify commentary.
(Fframe_initial_p): New function.
(syms_of_terminal): Expose it.
(init_initial_terminal): Update commentary now that
menu-bar-update-buffers uses frame-initial-p (bug#53740).

* test/lisp/xt-mouse-tests.el (with-xterm-mouse-mode): Simulate the
lack of an initial terminal by overriding frame-initial-p now
that turn-on-xterm-mouse-tracking-on-terminal uses it.
* test/src/terminal-tests.el: New file.
---
 test/src/terminal-tests.el | 55 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 test/src/terminal-tests.el

(limited to 'test/src')

diff --git a/test/src/terminal-tests.el b/test/src/terminal-tests.el
new file mode 100644
index 00000000000..85c4fa04efc
--- /dev/null
+++ b/test/src/terminal-tests.el
@@ -0,0 +1,55 @@
+;;; terminal-tests.el --- tests for terminal.c -*- lexical-binding: t -*-
+
+;; Copyright (C) 2026 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'ert)
+
+(ert-deftest frame-initial-p ()
+  "Test `frame-initial-p' behavior."
+  (should-not (frame-initial-p t))
+  (should-not (frame-initial-p (current-buffer)))
+  (should-not (frame-initial-p (selected-window)))
+  ;; "Initial frame" implies "initial terminal", and
+  ;; no other terminal can have the initial frame.
+  (should-not (xor (equal (terminal-name) "initial_terminal")
+                   (frame-initial-p)))
+  ;; Initial frame implies its terminal is a termcap-like
+  ;; text-mode terminal.
+  (should (or (not (frame-initial-p))
+              (eq (terminal-live-p nil) t)))
+  ;; It similarly implies a termcap-like text-mode frame.
+  (should (or (not (frame-initial-p))
+              (eq (frame-live-p (selected-frame)) t)))
+  (dolist (ft (append '(nil) (frame-list) (terminal-list)))
+    (ert-info ((prin1-to-string ft) :prefix "Argument: ")
+      (should-not (xor (equal (terminal-name ft) "initial_terminal")
+                       (frame-initial-p ft)))
+      (should (or (not (frame-initial-p ft))
+                  (eq (terminal-live-p ft) t)))))
+  (cond (noninteractive
+         ;; Batch mode should have an initial frame.
+         (should (any #'frame-initial-p (frame-list)))
+         (should (any #'frame-initial-p (terminal-list))))
+        ((not (daemonp))
+         ;; Non-daemon interactive mode should have none.
+         (should-not (any #'frame-initial-p (frame-list)))
+         (should-not (any #'frame-initial-p (terminal-list))))))
+
+;;; terminal-tests.el ends here
-- 
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