patch 9.1.0496: matched text is highlighted case-sensitively

Problem:  matched text is highlighted case-sensitively
Solution: use MB_STRNICMP, update highlighting when the base changes
          (glepnir)

fixes: #15021
closes: #15023

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/insexpand.c

@@ -1448,7 +1448,7 @@ ins_compl_show_pum(void)
     char_u *
 ins_compl_leader(void)
 {
-    return compl_leader;
+    return compl_leader != NULL ? compl_leader : compl_orig_text;
 }
 
 /*

src/popupmenu.c

@@ -461,7 +461,7 @@ pum_compute_text_attrs(char_u *text, hlf_T hlf)
     if (in_fuzzy)
 	ga = fuzzy_match_str_with_pos(text, leader);
     else
-	matched_start = STRNCMP(text, leader, leader_len) == 0;
+	matched_start = MB_STRNICMP(text, leader, leader_len) == 0;
 
     while (*ptr != NUL)
     {

src/testdir/dumps/Test_pum_highlights_09.dump

@@ -0,0 +1,20 @@
+|f+0&#ffffff0> @73
+|f+0#00e0e07#e0e0e08|o+0#0000001&@1| @11| +0#4040ff13#ffffff0@59
+|F+0#0000e05#ffd7ff255|o+0#0000001&@1|b|a|r| @8| +0#4040ff13#ffffff0@59
+|f+0#0000e05#ffd7ff255|o+0#0000001&@1|B|a|z| @8| +0#4040ff13#ffffff0@59
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|-+2#0000000&@1| |I|N|S|E|R|T| |-@1| +0&&@62

src/testdir/test_popup.vim

@@ -1400,6 +1400,20 @@ func Test_pum_highlights_match()
             \ { 'word': '你可好吗' },
             \]}
     endfunc
+
+    func Comp()
+      let col = col('.')
+      if getline('.') == 'f'
+        let col -= 1
+      endif
+      call complete(col, [
+            \ #{word: "foo", icase: 1},
+            \ #{word: "Foobar", icase: 1},
+            \ #{word: "fooBaz", icase: 1},
+            \])
+      return ''
+    endfunc
+
     set omnifunc=Omni_test
     set completeopt=menu,noinsert,fuzzy
     hi PmenuMatchSel  ctermfg=6 ctermbg=7
@@ -1463,7 +1477,14 @@ func Test_pum_highlights_match()
     call term_sendkeys(buf, ":set norightleft\<CR>")
   endif
 
+  call term_sendkeys(buf, "S\<C-R>=Comp()\<CR>f")
+  call VerifyScreenDump(buf, 'Test_pum_highlights_09', {})
+  call term_sendkeys(buf, "o\<BS>\<C-R>=Comp()\<CR>")
+  call VerifyScreenDump(buf, 'Test_pum_highlights_09', {})
+
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
   call TermWait(buf)
+
   call StopVimInTerminal(buf)
 endfunc
 

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    496,
 /**/
     495,
 /**/