main 93a415c4: Replace $...$ depending on major-mode

[Arash Esbati]

branch: main
commit 93a415c4537228ad5f9757244611e9eb8f57727d
Author: Arash Esbati <ar...@gnu.org>
Commit: Arash Esbati <ar...@gnu.org>

    Replace $...$ depending on major-mode
    
    * NEWS.org (Changed): Announce the change.
    
    * doc/auctex.texi (Quotes): Adjust accordingly.
    
    * tex.el (TeX-insert-dollar-electric-region): Replace $...$ by
    $$...$$ in `plain-TeX-mode' and by \[...\] in `LaTeX-mode' and
    `docTeX-mode'.  (bug#78006)
---
 NEWS.org        | 2 ++
 doc/auctex.texi | 3 ++-
 tex.el          | 7 +++++--
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/NEWS.org b/NEWS.org
index a2ca10d3..8917727b 100644
--- a/NEWS.org
+++ b/NEWS.org
@@ -16,6 +16,8 @@
 ** Changed
 
 - AUCTeX now requires GNU Emacs 28.1 or higher.
+- Replace $..$ with \[..\] in ~LaTeX-mode~ and any derived mode when
+  hitting =$= repeatedly where ~TeX-electric-math~ is non-~nil~.
 
 ** Fixed
 
diff --git a/doc/auctex.texi b/doc/auctex.texi
index 7cca6f8b..46ed6f95 100644
--- a/doc/auctex.texi
+++ b/doc/auctex.texi
@@ -447,7 +447,8 @@ symbols for opening and closing inline equation and keep 
the region
 active, leaving point after the closing symbol.  By pressing repeatedly
 @kbd{$} while the region is active you can toggle between an inline
 equation, a display equation, and no equation.  To be precise,
-@samp{$...$} is replaced by @samp{$$...$$}, whereas @samp{\(...\)} is
+@samp{$...$} is replaced by @samp{$$...$$} in plain-TeX-mode or
+@samp{\[...\]} in LaTeX-mode and docTeX-mode, whereas @samp{\(...\)} is
 replaced by @samp{\[...\]}.
 @end defopt
 
diff --git a/tex.el b/tex.el
index 3d28b2c6..e90252d8 100644
--- a/tex.el
+++ b/tex.el
@@ -6188,10 +6188,13 @@ See `TeX-electric-math'."
              (re-search-forward "\\=\\$\\$\\([^z-a]*\\)\\$\\$" (mark) t)))
     (replace-match "\\1" t)
     (set-mark (match-beginning 0)))
-   ;; $...$ to $$...$$
+   ;; $...$ to $$...$$ or \[...\] dep. on mode:
    ((and (eq last-command #'TeX-insert-dollar)
          (re-search-forward "\\=\\$\\([^z-a]*\\)\\$" (mark) t))
-    (replace-match "$$\\1$$" t)
+    (replace-match (if (derived-mode-p 'LaTeX-mode)
+                       "\\\\[\\1\\\\]"
+                     "$$\\1$$")
+                   t)
     (set-mark (match-beginning 0)))
    ;; \(...\) to \[...\]
    ((and (eq last-command #'TeX-insert-dollar)