bug#51426: 29.0.50; [PATCH] Should 'comint-term-environment' be connection-aware?

[Jim Porter <jporterbugs@gmail.com>]

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On 10/28/2021 1:02 AM, Michael Albinus wrote:
>> +@code{comint-terminfo-terminal} to let you choose a terminal with more
>> +advanced features, as defined in your system's terminfo database.
>> +When @code{system-uses-terminfo} is non-nil, Emacs will use this
>> +option as the value for @env{TERM}.
> 
> "this option" sounds like Emacs uses system-uses-terminfo for TERM, at
> least in my ears. Could you pls rephrase it a little bit?

Looking at it again, I definitely agree. I've tried to reword it without 
making it too much more verbose. How's this?

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From 7fe3e2b6c118508300e08da04f039d21403ff9d0 Mon Sep 17 00:00:00 2001
From: Jim Porter <jporterbugs@gmail.com>
Date: Thu, 28 Oct 2021 08:45:15 -0700
Subject: [PATCH] Support setting comint terminal connection-locally

* lisp/comint.el (comint-term-environment): Make it connection-aware.
* doc/emacs/misc.texi (Shell Options): Document the above change, and
explain how this interacts with 'system-uses-terminfo'.
* etc/NEWS: Announce the above change.
---
 doc/emacs/misc.texi | 12 +++++++++---
 etc/NEWS            |  8 ++++++++
 lisp/comint.el      | 13 +++++++------
 3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/doc/emacs/misc.texi b/doc/emacs/misc.texi
index 5123a716dc..7e7f7c5e27 100644
--- a/doc/emacs/misc.texi
+++ b/doc/emacs/misc.texi
@@ -1497,14 +1497,20 @@ Shell Options
 underlying shell, of course.
 
 @vindex comint-terminfo-terminal
+@vindex system-uses-terminfo
 @vindex TERM@r{, environment variable, in sub-shell}
 Comint mode sets the @env{TERM} environment variable to a safe default
 value, but this value disables some useful features.  For example,
 color is disabled in applications that use @env{TERM} to determine if
 color is supported.  Therefore, Emacs provides an option
-@code{comint-terminfo-terminal}, which you can set to a terminal that
-is present in your system's terminfo database, in order to take
-advantage of advanced features of that terminal.
+@code{comint-terminfo-terminal} to let you choose a terminal with more
+advanced features, as defined in your system's terminfo database.
+Emacs will use this option as the value for @env{TERM} so long as
+@code{system-uses-terminfo} is non-nil.
+
+Both @code{comint-terminfo-terminal} and @code{system-uses-terminfo}
+can be declared as connection-local to adjust these options to match
+what a remote system expects (@pxref{Connection Variables}).
 
 @node Terminal emulator
 @subsection Emacs Terminal Emulator
diff --git a/etc/NEWS b/etc/NEWS
index c1b8adc511..2a8a3f08e7 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -183,6 +183,14 @@ To improve security, if an sql product has ':password-in-comint' set
 to t, a password supplied via the minibuffer will be sent in-process,
 as opposed to via the command-line.
 
+** Comint
+
++++
+*** 'comint-term-environment' is now aware of connection-local variables.
+The option 'comint-terminfo-terminal' and variable
+'system-uses-terminfo' can now be set as connection-local variables to
+change the terminal used on a remote host.
+
 \f
 * New Modes and Packages in Emacs 29.1
 
diff --git a/lisp/comint.el b/lisp/comint.el
index e925b3a4b6..c114bdf758 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -889,12 +889,13 @@ comint-term-environment
   ;; and there is no way for us to define it here.
   ;; Some programs that use terminfo get very confused
   ;; if TERM is not a valid terminal type.
-  (if (and (boundp 'system-uses-terminfo) system-uses-terminfo)
-      (list (format "TERM=%s" comint-terminfo-terminal)
-            "TERMCAP="
-            (format "COLUMNS=%d" (window-width)))
-    (list "TERM=emacs"
-          (format "TERMCAP=emacs:co#%d:tc=unknown:" (window-width)))))
+  (with-connection-local-variables
+   (if system-uses-terminfo
+       (list (format "TERM=%s" comint-terminfo-terminal)
+             "TERMCAP="
+             (format "COLUMNS=%d" (window-width)))
+     (list "TERM=emacs"
+           (format "TERMCAP=emacs:co#%d:tc=unknown:" (window-width))))))
 
 (defun comint-nonblank-p (str)
   "Return non-nil if STR contains non-whitespace syntax."
-- 
2.25.1