bug#45660: 28.0.50; Changed word/whitespace syntax

[Eli Zaretskii <eliz@gnu.org>]

> From: Juri Linkov <juri@linkov.net>
> Date: Mon, 04 Jan 2021 19:25:23 +0200
> 
> Some unidentified recent change during the last week broke the
> definition of word syntax and whitespace syntax.

It's this commit:

  commit 70484f92a1807897dcd16189442a45385c6e7bbb
  Author:     Eli Zaretskii <eliz@gnu.org>
  AuthorDate: Sat Jan 2 12:42:16 2021 +0200
  Commit:     Eli Zaretskii <eliz@gnu.org>
  CommitDate: Sat Jan 2 12:42:16 2021 +0200

      Fix syntax of symbol and punctuation characters

      * lisp/international/characters.el: Adjust syntax of punctuation
      and symbol charcaters to follow that of Unicode properties.
      (Bug#44974)


diff --git a/lisp/international/characters.el b/lisp/international/characters.el
index 64460b4..88f2e20 100644
--- a/lisp/international/characters.el
+++ b/lisp/international/characters.el
@@ -317,6 +317,7 @@ ?L
 (modify-syntax-entry #x5be ".") ; MAQAF
 (modify-syntax-entry #x5c0 ".") ; PASEQ
 (modify-syntax-entry #x5c3 ".") ; SOF PASUQ
+(modify-syntax-entry #x5c6 ".") ; NUN HAFUKHA
 (modify-syntax-entry #x5f3 ".") ; GERESH
 (modify-syntax-entry #x5f4 ".") ; GERSHAYIM
 
@@ -521,6 +522,9 @@ ?L
   ;; syntax: ¢£¤¥¨ª¯²³´¶¸¹º.)  There should be a well-defined way of
   ;; relating Unicode categories to Emacs syntax codes.
 
+  ;; FIXME: We should probably just use the Unicode properties to set
+  ;; up the syntax table.
+
   ;; NBSP isn't semantically interchangeable with other whitespace chars,
   ;; so it's more like punctuation.
   (set-case-syntax ?  "." tbl)
@@ -558,7 +562,7 @@ ?L
     (setq c (1+ c)))
 
   ;; Latin Extended Additional
-  (modify-category-entry '(#x1e00 . #x1ef9) ?l)
+  (modify-category-entry '(#x1E00 . #x1EF9) ?l)
 
   ;; Latin Extended-C
   (setq c #x2C60)
@@ -579,13 +583,13 @@ ?L
     (setq c (1+ c)))
 
   ;; Greek
-  (modify-category-entry '(#x0370 . #x03ff) ?g)
+  (modify-category-entry '(#x0370 . #x03FF) ?g)
 
   ;; Armenian
   (setq c #x531)
 
   ;; Greek Extended
-  (modify-category-entry '(#x1f00 . #x1fff) ?g)
+  (modify-category-entry '(#x1F00 . #x1FFF) ?g)
 
   ;; cyrillic
   (modify-category-entry '(#x0400 . #x04FF) ?y)
@@ -605,40 +609,43 @@ ?L
   (while (<= c #x200F)
     (set-case-syntax c "." tbl)
     (setq c (1+ c)))
-  ;; Fixme: These aren't all right:
   (setq c #x2010)
-  (while (<= c #x2016)
-    (set-case-syntax c "_" tbl)
+  ;; Fixme: What to do with characters that have Pi and Pf
+  ;; Unicode properties?
+  (while (<= c #x2017)
+    (set-case-syntax c "." tbl)
     (setq c (1+ c)))
   ;; Punctuation syntax for quotation marks (like `)
-  (while (<= c #x201f)
+  (while (<= c #x201F)
     (set-case-syntax  c "." tbl)
     (setq c (1+ c)))
-  ;; Fixme: These aren't all right:
   (while (<= c #x2027)
-    (set-case-syntax c "_" tbl)
+    (set-case-syntax c "." tbl)
     (setq c (1+ c)))
-  (while (<= c #x206F)
+  (setq c #x2030)
+  (while (<= c #x205E)
     (set-case-syntax c "." tbl)
     (setq c (1+ c)))
+  (let ((chars '(?‹ ?› ?⁄ ?⁒)))
+    (while chars
+      (modify-syntax-entry (car chars) "_")
+      (setq chars (cdr chars))))
 
-  ;; Fixme: The following blocks might be better as symbol rather than
-  ;; punctuation.
   ;; Arrows
   (setq c #x2190)
   (while (<= c #x21FF)
-    (set-case-syntax c "." tbl)
+    (set-case-syntax c "_" tbl)
     (setq c (1+ c)))
   ;; Mathematical Operators
   (while (<= c #x22FF)
-    (set-case-syntax c "." tbl)
+    (set-case-syntax c "_" tbl)
     (setq c (1+ c)))
   ;; Miscellaneous Technical
   (while (<= c #x23FF)
-    (set-case-syntax c "." tbl)
+    (set-case-syntax c "_" tbl)
     (setq c (1+ c)))
   ;; Control Pictures
-  (while (<= c #x243F)
+  (while (<= c #x244F)
     (set-case-syntax c "_" tbl)
     (setq c (1+ c)))
 
@@ -652,13 +659,13 @@ ?L
   ;; Supplemental Mathematical Operators
   (setq c #x2A00)
   (while (<= c #x2AFF)
-    (set-case-syntax c "." tbl)
+    (set-case-syntax c "_" tbl)
     (setq c (1+ c)))
 
   ;; Miscellaneous Symbols and Arrows
   (setq c #x2B00)
   (while (<= c #x2BFF)
-    (set-case-syntax c "." tbl)
+    (set-case-syntax c "_" tbl)
     (setq c (1+ c)))
 
   ;; Coptic
@@ -676,17 +683,34 @@ ?L
 
   ;; Symbols for Legacy Computing
   (setq c #x1FB00)
+  (while (<= c #x1FBCA)
+    (set-case-syntax c "_" tbl)
+    (setq c (1+ c)))
+  ;; FIXME: Should these be digits?
   (while (<= c #x1FBFF)
     (set-case-syntax c "." tbl)
     (setq c (1+ c)))
 
   ;; Fullwidth Latin
-  (setq c #xff21)
-  (while (<= c #xff3a)
+  (setq c #xFF01)
+  (while (<= c #xFF0F)
+    (set-case-syntax c "." tbl)
+    (setq c (1+ c)))
+  (set-case-syntax #xFF04 "_" tbl)
+  (set-case-syntax #xFF0B "_" tbl)
+  (setq c #xFF21)
+  (while (<= c #xFF3A)
     (modify-category-entry c ?l)
     (modify-category-entry (+ c #x20) ?l)
     (setq c (1+ c)))
 
+  ;; Halfwidth Latin
+  (setq c #xFF64)
+  (while (<= c #xFF65)
+    (set-case-syntax c "." tbl)
+    (setq c (1+ c)))
+  (set-case-syntax #xFF61 "." tbl)
+
   ;; Combining diacritics
   (modify-category-entry '(#x300 . #x362) ?^)
   ;; Combining marks


> I noticed the change of behavior in markchars-mode that now
> disregards the character "NARROW NO-BREAK SPACE" as the word
> separator between thousands, i.e.:
> 
> In Emacs 27:
> (and (string-match "\\<\\w+\\>" "4 096") (match-end 0))
> 1
> 
> In Emacs 28:
> (and (string-match "\\<\\w+\\>" "4 096") (match-end 0))
> 5
> 
> Note there is the character "NARROW NO-BREAK SPACE" between "4" and "096".

Previously, many characters, including u+202F, had the punctuation
('.') syntax.  I modified that to be more close to the Unicode
Character Database (UCD), and u+202F is not a punctuation character
according to the UCD.  It has the Zs general category, which means
"space separator", the same as SPC, NBSP, EN SPACE, and others.

Removing u+202F and other similar characters from the "punctuation"
group had the side effect of leaving it at the default 'w' syntax.

Should we make all Zs characters have the ' ' (whitespace) syntax?
That should be easy, but we should try being consistent in this
regard.