bug#39181: 27.0.50; [PATCH] Allow users to store & restore gdb-mi layout

[martin rudalics]

> Here is the patch.

Thanks. It gets me here the following warnings when building on master
(sorry, I'm a complete ignorant of the 'cl-' snafu):

  ELC      progmodes/gdb-mi.elc

In toplevel form:
../../lisp/progmodes/gdb-mi.el:4738:1: Warning: Unused lexical variable
    ‘window-config’

In end of data:
../../lisp/progmodes/gdb-mi.el:5069:1: Warning: the following functions might
    not be defined at runtime: cl-delete-if, cl-find-if, cl-mapcar

A few remarks:

+  "If non-nil, gdb loads this window layout file on startup.
+If not absolute, GDB will look under `gdb-window-layout-directory'."

We should settle in descriptions on whether we write gdb or GDB.  Also,
"if not absolute" is too terse IMHO.

+  (define-key menu [load-layout] '("Load window layout" "Load GDB window layout 
from a file" . gdb-load-window-layout))
+  (define-key menu [save-layout] '("Save window layout" "Save current GDB window 
layout to a file" . gdb-save-window-layout))

I think we could omit the "window" in these which should allow us to,
instead of

+    '(menu-item "Restore window layout"

say

+    '(menu-item "Restore layout after quit"

so it becomes more clear that "load" and "save" act _immediately_ on the
current state while "restore" is a more general setting that becomes
effective only when the user quits.  (Note also that in general we
cannot guarantee that menu tooltips are always shown on each and every
system where Emacs runs.)

Also, I would mention all four possible values of
'gdb-restore-window-layout-after-quit' (currently "toggle" indicates
that there are only two of them) like, for example, with the side values
for tool-bar mode.

+  "Return a buffer displaying source file or nil.
+
+The source file would be the most relevant file or the main file."

This is IMHO too terse in every respect.  Neither "source file" nor
"main file" are canonical terms in the context of GDB so we should
explain here how they are set up (what is nil in this context?).

+E.g., locals buffer, registers buffer, but don't include the main

I would say "Function buffers are locals buffers, ...".

+(defun gdb--buffer-type (buffer)
+  "Return the buffer type of BUFFER or nil.

Maybe

"Return the type of BUFFER if it is a GDB function buffer."

would be better.

Thanks for your work on this, martin