patch 9.1.1640: Unicode has deprecated some code-points

Problem:  Unicode has deprecated some code-points
Solution: Update the digraph tables to align with the Unicode v16
          release (David Friant)

This commit updates the digraphs Left-Pointing Angle Bracket '</'
and Right-Pointing Angle Bracket '/>' to account for the fact that
the old Unicode codepoints for them (2329 and 232A, respectively)
have been deprecated. As per the Miscellaneous Technical code chart
(https://www.unicode.org/charts/PDF/U2300.pdf), the old digraphs
have been reassigned to the CJK Left Angle Bracket and Right Angle
Bracket (3008 and 3009) with their declaration moved to the
appropriate block.

This commit also introduces the new digraphs '<[' and ']>' to
represent the Mathematical Left Angle Bracket and Mathematical
Right Angle Bracket (27E8 and 27E9) to replace the deprecated code
points in the Technical block.

Tests have been added and, I believe, the documentation has been
updated accordingly.

closes: #17990

Signed-off-by: David Friant <friant@HPEnvyx360.friant.dev>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/digraph.txt

@@ -1,4 +1,4 @@
-*digraph.txt*   For Vim version 9.1.  Last change: 2025 Feb 02
+*digraph.txt*   For Vim version 9.1.  Last change: 2025 Aug 16
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1105,8 +1105,8 @@ char  digraph	hex	dec	official name ~
 ⌕	TR	2315	8981	TELEPHONE RECORDER
 ⌠	Iu	2320	8992	TOP HALF INTEGRAL
 ⌡	Il	2321	8993	BOTTOM HALF INTEGRAL
-〈	</	2329	9001	LEFT-POINTING ANGLE BRACKET
+⟨	<[	27E8	10040	LEFT MATHEMATICAL ANGLE BRACKET
-〉	/>	232A	9002	RIGHT-POINTING ANGLE BRACKET
+⟩	]>	27E9	10041	RIGHT MATHEMATICAL ANGLE BRACKET
 ␣	Vs	2423	9251	OPEN BOX
 ⑀	1h	2440	9280	OCR HOOK
 ⑁	3h	2441	9281	OCR CHAIR
@@ -1246,6 +1246,8 @@ char  digraph	hex	dec	official name ~
 々	*_	3005	12293	IDEOGRAPHIC ITERATION MARK
 〆	;_	3006	12294	IDEOGRAPHIC CLOSING MARK
 〇	0_	3007	12295	IDEOGRAPHIC NUMBER ZERO
+〈	</	3008	12296	LEFT ANGLE BRACKET
+〉	/>	3009	12297	RIGHT ANGLE BRACKET
 《	<+	300A	12298	LEFT DOUBLE ANGLE BRACKET
 》	>+	300B	12299	RIGHT DOUBLE ANGLE BRACKET
 「	<'	300C	12300	LEFT CORNER BRACKET

runtime/doc/version9.txt

@@ -1,4 +1,4 @@
-*version9.txt*  For Vim version 9.1.  Last change: 2025 Aug 12
+*version9.txt*  For Vim version 9.1.  Last change: 2025 Aug 16
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -41739,6 +41739,12 @@ Others: ~
 - The close button shown in the non-GUI 'tabline' will only be visible if the
   'mouse' option contains either "a" or any of the flags "n", "v", or "i".
 - |C-indenting| handles compound literals.
+- The digraphs "</" (LEFT-POINTING ANGLE BRACKET) and ">/" (RIGHT-POINTING
+  ANGLE BRACKET) have been changed to represent LEFT ANGLE BRACKET and RIGHT
+  ANGLE BRACKET to match the Unicode Miscellaneous Technical code chart from
+  Unicode 16.
+- Two additional digraphs have been added: LEFT ANGLE BRACKET "<[" and RIGHT
+  ANGLE BRACKET "]>".
 
 							*added-9.2*
 Added ~

src/digraph.c

@@ -1028,8 +1028,8 @@ static digr_T digraphdefault[] = {
 	{'T', 'R', 0x2315},
 	{'I', 'u', 0x2320},
 	{'I', 'l', 0x2321},
-	{'<', '/', 0x2329},
+	{'<', '[', 0x27e8},
-	{'/', '>', 0x232a},
+	{']', '>', 0x27e9},
 #   define DG_START_OTHER2 0x2423
 	{'V', 's', 0x2423},
 	{'1', 'h', 0x2440},
@@ -1176,6 +1176,8 @@ static digr_T digraphdefault[] = {
 	{'*', '_', 0x3005},
 	{';', '_', 0x3006},
 	{'0', '_', 0x3007},
+	{'<', '/', 0x3008},
+	{'/', '>', 0x3009},
 	{'<', '+', 0x300a},
 	{'>', '+', 0x300b},
 	{'<', '\'', 0x300c},

src/testdir/test_digraph.vim

@@ -612,5 +612,16 @@ func Test_digraph_getlist_function()
   call assert_fails('call digraph_getlist(0z12)', 'E1212: Bool required for argument 1')
 endfunc
 
+func Test_digraph_angle_bracket_patch()
+  " Ensure that the deprecated angle brackets 2329/232A ('</','/>') are not used
+  call assert_notequal('〈', digraph_get('</'))
+  call assert_notequal('〉', digraph_get('/>'))
+  " Ensure that the CJK angle brackets 3008/3009 ('</','/>') are used
+  call assert_equal('〈', digraph_get('</'))
+  call assert_equal('〉', digraph_get('/>'))
+  " Ensure that the mathematical angle brackets 27E8/27E9 ('<[',']>') are defined
+  call assert_equal('⟨', digraph_get('<['))
+  call assert_equal('⟩', digraph_get(']>'))
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -719,6 +719,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1640,
 /**/
     1639,
 /**/