runtime(make): syntax highlighting update for makeDefine

Previously contents in makeDefine are nearly highlighted as Define, so
comments and targets shares the same color as Define, making it hard to
distinguish if someone write large block of targets-recipes as defined
function.

Such scenario is common in building data analysis pipeline. Recipes are
reused and targets may have multiple variables, and a single % implicit
rule is not enough.

closes: #18403

Signed-off-by: Yiyang Wu <xgreenlandforwyy@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: littlewu2508

runtime/syntax/make.vim

@@ -5,6 +5,7 @@
 " URL:		https://github.com/vim/vim/blob/master/runtime/syntax/make.vim
 " Last Change:	2022 Nov 06
 " 2025 Apr 15 by Vim project: rework Make flavor detection (#17089)
+" 2025 Oct 12 by Vim project: update makeDefine highlighting (#18403)
 
 " quit when a syntax file was already loaded
 if exists("b:current_syntax")
@@ -23,7 +24,7 @@ syn match makeNextLine	"\\\n\s*"
 
 " catch unmatched define/endef keywords.  endef only matches it is by itself on a line, possibly followed by a commend
 syn region makeDefine start="^\s*define\s" end="^\s*endef\s*\(#.*\)\?$"
-	\ contains=makeStatement,makeIdent,makePreCondit,makeDefine
+	\ contains=makeStatement,makeIdent,makePreCondit,makeDefine,makeComment,makeTargetinDefine
 
 if get(b:, 'make_flavor', s:make_flavor) == 'microsoft'
   " Microsoft Makefile specials
@@ -33,20 +34,26 @@ if get(b:, 'make_flavor', s:make_flavor) == 'microsoft'
   syn case match
 endif
 
-" identifiers
+" identifiers; treat $$X like $X inside makeDefine
+syn match makeIdent	"\$\$\w*"
+syn match makeIdent	"\$\$\$\$\w*" containedin=makeDefine
+syn match makeIdent	"\$[^({]"
+syn match makeIdent	"\$\$[^({]" containedin=makeDefine
+syn match makeIdent	"^ *[^:#= \t]*\s*[:+?!*]="me=e-2
+syn match makeIdent	"^ *[^:#= \t]*\s*::="me=e-3
+syn match makeIdent	"^ *[^:#= \t]*\s*="me=e-1
+syn match makeIdent	"%"
 if get(b:, 'make_flavor', s:make_flavor) == 'microsoft'
   syn region makeIdent	start="\$(" end=")" contains=makeStatement,makeIdent
   syn region makeIdent	start="\${" end="}" contains=makeStatement,makeIdent
+  syn region makeIdent	start="\$\$(" end=")" containedin=makeDefine contains=makeStatement,makeIdent
+  syn region makeIdent	start="\$\${" end="}" containedin=makeDefine contains=makeStatement,makeIdent
 else
   syn region makeIdent	start="\$(" skip="\\)\|\\\\" end=")" contains=makeStatement,makeIdent
   syn region makeIdent	start="\${" skip="\\}\|\\\\" end="}" contains=makeStatement,makeIdent
+  syn region makeIdent	start="\$\$(" skip="\\)\|\\\\" end=")" containedin=makeDefine contains=makeStatement,makeIdent
+  syn region makeIdent	start="\$\${" skip="\\}\|\\\\" end="}" containedin=makeDefine contains=makeStatement,makeIdent
 endif
-syn match makeIdent	"\$\$\w*"
-syn match makeIdent	"\$[^({]"
-syn match makeIdent	"^ *[^:#= \t]*\s*[:+?!*]="me=e-2
-syn match makeIdent	"^ *[^:#= \t]*\s*::="me=e-3
-syn match makeIdent	"^ *[^:#= \t]*\s*="me=e-1
-syn match makeIdent	"%"
 
 " Makefile.in variables
 syn match makeConfig "@[A-Za-z0-9_]\+@"
@@ -55,6 +62,12 @@ syn match makeConfig "@[A-Za-z0-9_]\+@"
 syn match makeImplicit		"^\.[A-Za-z0-9_./\t -]\+\s*:$"me=e-1
 syn match makeImplicit		"^\.[A-Za-z0-9_./\t -]\+\s*:[^=]"me=e-2
 
+syn region makeTargetinDefine transparent matchgroup=makeTargetinDefine
+	\ start="^[~A-Za-z0-9_./$(){}%-][A-Za-z0-9_./\t ${}()%-]*&\?:\?:\{1,2}[^:=]"rs=e-1
+	\ end="[^\\]$"
+syn match makeTargetinDefine           "^[~A-Za-z0-9_./$(){}%*@-][A-Za-z0-9_./\t $(){}%*@-]*&\?::\=\s*$"
+	\ contains=makeIdent,makeSpecTarget,makeComment
+
 syn region makeTarget transparent matchgroup=makeTarget
 	\ start="^[~A-Za-z0-9_./$(){}%-][A-Za-z0-9_./\t ${}()%-]*&\?:\?:\{1,2}[^:=]"rs=e-1
 	\ end="[^\\]$"
@@ -155,6 +168,7 @@ hi def link makeCommands	Number
 endif
 hi def link makeImplicit	Function
 hi def link makeTarget		Function
+hi def link makeTargetinDefine		Function
 hi def link makeInclude		Include
 hi def link makePreCondit	PreCondit
 hi def link makeStatement	Statement