fix(qf): add code highlight

syntax/qf.vim

@@ -10,6 +10,7 @@ syntax match qfInfo   "\c\<info\>:\@="
 syntax match qfNote   "\c\<\(note\|hint\)\>:\@="
 syntax match qfPassed "\c\<\(ok\|passed\)\>"
 syntax match qfFailed "\c\<\fail\(ed\|ure\)\?s\?\>"
+syntax match qfCode   "\[.\+\]$"
 
 syntax match qfFileName     "^[^: ]*"                       nextgroup=qfLineCol
 syntax match qfLineCol      ":\(\d\+:\)\{,2} "  contained
@@ -22,6 +23,7 @@ highlight default link  qfInfo          DiagnosticInfo
 highlight default link  qfNote          DiagnosticHint
 highlight default link  qfPassed        DiagnosticOk
 highlight default link  qfFailed        DiagnosticError
+highlight default link  qfCode          Comment
 
 highlight clear         QuickFixLine
 highlight               QuickFixLine    gui=underline