runtime(vim): Update base-syntax, bug fixes

- Allow trailing backslashes in option values.
- Match :map-special modifier.
- Match :map-arguments case-sensitively.
- Remove <*Leader> from map modifier list and allow in RHS of a mapping.

closes: #16822

Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/vim.vim b/runtime/syntax/vim.vim
index e83c9b2..ac295e0 100644
--- a/runtime/syntax/vim.vim
+++ b/runtime/syntax/vim.vim
@@ -756,9 +756,9 @@
 syn match	vimCmplxRepeat	'@[0-9a-z".=@:]\ze\($\|[^a-zA-Z]\>\)'
 
 " Set command and associated set-options (vimOptions) with comment {{{2
-syn match	vimSet		"\<\%(setl\%[ocal]\|setg\%[lobal]\|se\%[t]\)\>" skipwhite nextgroup=vimSetBang,vimSetRegion
-syn region	vimSetRegion	contained	start="\S" skip=+\\\\\|\\|\|\n\s*\\\|\n\s*["#]\\ + matchgroup=vimCmdSep end="|" end="$" matchgroup=vimNotation end="<[cC][rR]>" keepend contains=@vimComment,@vimContinue,vimErrSetting,vimOption,vimSetAll,vimSetTermcap
-syn region	vimSetEqual	contained	matchgroup=vimOper start="[=:]\|[-+^]=" skip=+\\\\\|\\|\|\\\s\|\n\s*\\\|\n\s*["#]\\ \|^\s*\\\|^\s*["#]\\ + matchgroup=vimCmdSep end="|" end="\ze\s" end="$" contains=@vimContinue,vimCtrlChar,vimEnvvar,vimNotation,vimSetSep
+syn match	vimSet		"\<\%(setl\%[ocal]\|setg\%[lobal]\|se\%[t]\)\>" skipwhite nextgroup=vimSetBang,vimSetArgs
+syn region	vimSetArgs	contained	start="\S" skip=+\\|\|\n\s*\\\|\n\s*["#]\\ + matchgroup=vimCmdSep end="|" end="$" matchgroup=vimNotation end="<[cC][rR]>" keepend contains=@vimComment,@vimContinue,vimErrSetting,vimOption,vimSetAll,vimSetTermcap
+syn region	vimSetEqual	contained	matchgroup=vimOper start="[=:]\|[-+^]=" skip=+\\|\|\\\s\|\n\s*\\\|\n\s*["#]\\ \|^\s*\\\|^\s*["#]\\ + matchgroup=vimCmdSep end="|" end="\ze\s" end="$" contains=@vimContinue,vimCtrlChar,vimEnvvar,vimNotation,vimSetSep
 syn match	vimSetBang	contained	"\a\@1<=!" skipwhite nextgroup=vimSetAll,vimSetTermcap
 syn keyword	vimSetAll	contained	all nextgroup=vimSetMod
 syn keyword	vimSetTermcap	contained	termcap
@@ -880,15 +880,17 @@
 syn keyword vimUnmap cu[nmap] iu[nmap] lu[nmap] nun[map] ou[nmap] sunm[ap] tunma[p] vu[nmap] xu[nmap] skipwhite nextgroup=vimMapMod,vimMapLhs
 syn keyword	vimUnmap	unm[ap]	skipwhite nextgroup=vimMapBang,vimMapMod,vimMapLhs
 
-syn match	vimMapLhs	contained	"\%(.\|\S\)\+"		contains=vimCtrlChar,vimNotation skipwhite        nextgroup=vimMapRhs
-syn match	vimMapLhs	contained	"\%(.\|\S\)\+\ze\s*$"	contains=vimCtrlChar,vimNotation skipwhite skipnl nextgroup=vimMapRhsContinue
+syn match	vimMapLhs	contained	"\%(.\|\S\)\+"		contains=vimCtrlChar,vimNotation,vimMapLeader skipwhite        nextgroup=vimMapRhs
+syn match	vimMapLhs	contained	"\%(.\|\S\)\+\ze\s*$"	contains=vimCtrlChar,vimNotation,vimMapLeader skipwhite skipnl nextgroup=vimMapRhsContinue
 syn match	vimMapBang	contained	"\a\@1<=!"		skipwhite nextgroup=vimMapMod,vimMapLhs
-syn match	vimMapMod	contained	"\%#=1\c<\(buffer\|expr\|\(local\)\=leader\|nowait\|plug\|script\|sid\|unique\|silent\)\+>" contains=vimMapModKey,vimMapModErr skipwhite nextgroup=vimMapMod,vimMapLhs
-syn region	vimMapRhs	contained	start="\S" 	        skip=+\\|\|\@1<=|\|\n\s*\\\|\n\s*"\\ + end="|" end="$" contains=@vimContinue,vimCtrlChar,vimNotation skipnl nextgroup=vimMapRhsContinue
+syn match	vimMapMod	contained	"\%#=1<\%(buffer\|expr\|nowait\|script\|silent\|special\|unique\)\+>" contains=vimMapModKey,vimMapModErr skipwhite nextgroup=vimMapMod,vimMapLhs
+syn region	vimMapRhs	contained	start="\S" 	        skip=+\\|\|\@1<=|\|\n\s*\\\|\n\s*"\\ + end="|" end="$" contains=@vimContinue,vimCtrlChar,vimNotation,vimMapLeader skipnl nextgroup=vimMapRhsContinue
 " assume a continuation comment introduces the RHS
-syn region	vimMapRhsContinue	contained	start=+^\s*\%(\\\|"\\ \)+ skip=+\\|\|\@1<=|\|\n\s*\\\|\n\s*"\\ + end="|" end="$" contains=@vimContinue,vimCtrlChar,vimNotation
+syn region	vimMapRhsContinue	contained	start=+^\s*\%(\\\|"\\ \)+ skip=+\\|\|\@1<=|\|\n\s*\\\|\n\s*"\\ + end="|" end="$" contains=@vimContinue,vimCtrlChar,vimNotation,vimMapLeader
+syn match	vimMapLeader	contained	"\%#=1\c<\%(local\)\=leader>"	contains=vimMapLeaderKey
+syn keyword	vimMapModKey	contained	buffer expr nowait script silent special unique
 syn case ignore
-syn keyword	vimMapModKey	contained	buffer	expr	leader	localleader	nowait	plug	script	sid	silent	unique
+syn keyword	vimMapLeaderKey	contained	leader localleader
 syn case match
 
 " Menus: {{{2
@@ -954,7 +956,7 @@
 " Vim user commands
 
 " Compiler plugins
-syn match	vimCompilerSet	"\<CompilerSet\>"	skipwhite nextgroup=vimSetRegion
+syn match	vimCompilerSet	"\<CompilerSet\>"	skipwhite nextgroup=vimSetArgs
 
 " runtime/makemenu.vim
 syn match	vimSynMenu		"\<SynMenu\>"	skipwhite nextgroup=vimSynMenuPath
@@ -1533,6 +1535,8 @@
  hi def link vimLetRegister	Special
  hi def link vimLineComment	vimComment
  hi def link vimMapBang	vimBang
+ hi def link vimMapLeader	vimBracket
+ hi def link vimMapLeaderKey	vimNotation
  hi def link vimMapModKey	vimFuncSID
  hi def link vimMapMod	vimBracket
  hi def link vimMap	vimCommand