patch 9.1.1006: PmenuMatch completion highlight can be combined

Problem:  PmenuMatch completion highlight can be combined
Solution: Combine highlight groups PmenuMatch with Pmenu and
          PmenuMatchSel with PmenuSel (glepnir)

fixes: #15563
closes: #16408

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 7640ee1..2fb320e 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.1.  Last change: 2024 Dec 16
+*syntax.txt*	For Vim version 9.1.  Last change: 2025 Jan 11
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -5854,9 +5854,11 @@
 							*hl-PmenuThumb*
 PmenuThumb	Popup menu: Thumb of the scrollbar.
 							*hl-PmenuMatch*
-PmenuMatch	Popup menu: Matched text in normal item.
+PmenuMatch	Popup menu: Matched text in normal item. Applied in
+		combination with |hl-Pmenu|.
 							*hl-PmenuMatchSel*
-PmenuMatchSel	Popup menu: Matched text in selected item.
+PmenuMatchSel	Popup menu: Matched text in selected item. Applied in
+		combination with |hl-PmenuSel|.
 							*hl-ComplMatchIns*
 ComplMatchIns	Matched text of the currently inserted completion.
 							*hl-PopupNotification*
diff --git a/src/popupmenu.c b/src/popupmenu.c
index ea2edca..14cc69a 100644
--- a/src/popupmenu.c
+++ b/src/popupmenu.c
@@ -450,13 +450,18 @@
 		if (char_pos == ((int_u *)ga->ga_data)[i])
 		{
 		    new_attr = highlight_attr[is_select ? HLF_PMSI : HLF_PMNI];
+		    new_attr = hl_combine_attr(highlight_attr[hlf], new_attr);
 		    break;
 		}
 	    }
 	}
 	else if (matched_start && ptr < text + leader_len)
+	{
 	    new_attr = highlight_attr[is_select ? HLF_PMSI : HLF_PMNI];
+	    new_attr = hl_combine_attr(highlight_attr[hlf], new_attr);
+	}
 
+	new_attr = hl_combine_attr(highlight_attr[HLF_PNI], new_attr);
 	if (user_hlattr > 0)
 	    new_attr = hl_combine_attr(new_attr, user_hlattr);
 
diff --git a/src/testdir/dumps/Test_pum_highlights_18.dump b/src/testdir/dumps/Test_pum_highlights_18.dump
new file mode 100644
index 0000000..a57f7a2
--- /dev/null
+++ b/src/testdir/dumps/Test_pum_highlights_18.dump
@@ -0,0 +1,20 @@
+|f+0&#ffffff0|b> @72
+|f+0#40ffff15#e0e0e08|o+0#0000001&@1|B+0#40ffff15&|a+0#0000001&|z| @1|f|o@1|k|i|n|d| | +0#4040ff13#ffffff0@58
+|f+0&#ffd7ff255|o+0#0000001&@1|b+0#4040ff13&|a+0#0000001&|r| @1|f|o@1|k|i|n|d| | +0#4040ff13#ffffff0@58
+|f+0&#ffd7ff255|o+0#0000001&@1|b+0#4040ff13&|a+0#0000001&|l|a| |f|o@1|k|i|n|d| | +0#4040ff13#ffffff0@58
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|-+2#0000000&@1| |O|m|n|i| |c|o|m|p|l|e|t|i|o|n| |(|^|O|^|N|^|P|)| |m+0#00e0003&|a|t|c|h| |1| |o|f| |9| +0#0000000&@34
diff --git a/src/testdir/test_popup.vim b/src/testdir/test_popup.vim
index 0303c42..08b9cd9 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -1511,6 +1511,16 @@
   call term_sendkeys(buf, "\<ESC>S/non_existing_folder\<C-X>\<C-F>")
   call TermWait(buf, 50)
   call VerifyScreenDump(buf, 'Test_pum_highlights_15', {})
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
+
+  call term_sendkeys(buf, ":hi PmenuMatchSel ctermfg=14\<CR>")
+  call TermWait(buf, 50)
+  call term_sendkeys(buf, ":hi PmenuMatch ctermfg=12\<CR>")
+  call term_sendkeys(buf, ":set cot=menu,noinsert,fuzzy\<CR>")
+  call term_sendkeys(buf, "S\<C-X>\<C-O>")
+  call TermWait(buf, 50)
+  call term_sendkeys(buf, "fb")
+  call VerifyScreenDump(buf, 'Test_pum_highlights_18', {})
 
   call term_sendkeys(buf, "\<C-E>\<Esc>")
   call TermWait(buf)
diff --git a/src/version.c b/src/version.c
index 1927d9e..9d9f905 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1006,
+/**/
     1005,
 /**/
     1004,