Improve prettification of (La)TeX symbols

* lisp/textmodes/tex-mode.el (tex--prettify-symbols-alist): Remove
entry for "\\newline", which resulted in an invisible display.
Prettify "\\ " with OPEN BOX instead of BOTTOM SQUARE BRACKET.
(tex--prettify-symbols-compose-p): Skip composition when the
control backslash is itself escaped (bug#78752).

1 files changed, 26 insertions, 21 deletions

diff --git a/lisp/textmodes/tex-mode.el b/lisp/textmodes/tex-mode.el
index e8bc1400a3a..d4885e4e009 100644
--- a/lisp/textmodes/tex-mode.el
+++ b/lisp/textmodes/tex-mode.el
@@ -3369,7 +3369,6 @@ There might be text before point."
     ("\\neg" . ?¬)
     ("\\neq" . ?≠)
     ("\\nequiv" . ?≢)
-    ("\\newline" . ?
)
     ("\\nexists" . ?∄)
     ("\\ngeq" . ?≱)
     ("\\ngeqq" . ?≱)
@@ -3840,32 +3839,38 @@ There might be text before point."
     ("\\S" . ?§)
     ("\\Finv" . ?Ⅎ)
     ("\\Game" . ?⅁)
-    ("\\ " . 9141) ; Literal ?��� breaks indentation
+    ("\\ " . ?␣) ; Use ?��� (OPEN BOX) and not ?⎵ (BOTTOM SQUARE BRACKET)
     ("\\lvert" . ?|)
     ("\\rvert" . ?|)
     ("\\lVert" . ?‖)
     ("\\rVert" . ?‖))
   "A `prettify-symbols-alist' usable for (La)TeX modes.")
 
-(defun tex--prettify-symbols-compose-p (_start end _match)
-  (or
-   ;; If the matched symbol doesn't end in a word character, then we
-   ;; simply allow composition.  The symbol is probably something like
-   ;; \|, \(, etc.
-   (not (eq ?w (char-syntax (char-before end))))
-   ;; Else we look at what follows the match in order to decide.
-   (let* ((after-char (char-after end))
-          (after-syntax (char-syntax after-char)))
-     (not (or
-           ;; Don't compose \alpha@foo.
-           (eq after-char ?@)
-           ;; The \alpha in \alpha2 or \alpha-\beta may be composed but
-           ;; of course \alphax may not.
-           (and (eq after-syntax ?w)
-                (not (memq after-char
-                           '(?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9 ?+ ?- ?' ?\"))))
-           ;; Don't compose inside verbatim blocks.
-           (eq 2 (nth 7 (syntax-ppss))))))))
+(defun tex--prettify-symbols-compose-p (start end _match)
+  (if (save-excursion
+        (goto-char start)
+        ;; Skip composition when the control backslash at START is
+        ;; itself escaped, as in constructs like \"\\\\S\".
+        (not (zerop (mod (skip-chars-backward "\\\\") 2))))
+      nil
+    (or
+     ;; If the matched symbol doesn't end in a word character, then we
+     ;; simply allow composition.  The symbol is probably something like
+     ;; \|, \(, etc.
+     (not (eq ?w (char-syntax (char-before end))))
+     ;; Else we look at what follows the match in order to decide.
+     (let* ((after-char (char-after end))
+            (after-syntax (char-syntax after-char)))
+       (not (or
+             ;; Don't compose \alpha@foo.
+             (eq after-char ?@)
+             ;; The \alpha in \alpha2 or \alpha-\beta may be composed but
+             ;; of course \alphax may not.
+             (and (eq after-syntax ?w)
+                  (not (memq after-char
+                             '(?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9 ?+ ?- ?' ?\"))))
+             ;; Don't compose inside verbatim blocks.
+             (eq 2 (nth 7 (syntax-ppss)))))))))
 
 
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