Made vim highlighting work mostly how I want now.

I made `cpp.cplusplus` a hybrid filetype which tricks the vim
highlighting into believing that we're really in raw C++ for the
purposes of the core vim highlighting rules.  My `cplusplus` type
adds more bits to the core stuff, but mostly exists to let
doxygen slip in the way that I want it to.

vim/after/syntax/cplusplus.vim

@@ -1,11 +1,24 @@
+if exists("b:current_syntax")
+  unlet b:current_syntax
+endif
+
+syn include @cxxInDoxygen syntax/cpp.vim
+
+unlet b:current_syntax
 
 " This enables Basic C++ support, with my extensions.
+let c_no_bracket_error=1
+let c_no_curly_error=1
 if version < 600
   so <sfile>:p:h/cpp.vim
 else
   runtime! syntax/cpp.vim
 endif
 
+if exists("b:current_syntax")
+  unlet b:current_syntax
+endif
+
 " This enables doxygen simultaneous with C++.
 if version < 600
   so <sfile>:p:h/doxygen.vim
@@ -13,3 +26,7 @@ else
   runtime! syntax/doxygen.vim
 endif
 
+
+let b:current_syntax = "cplusplus"
+syn sync clear
+syn sync fromstart

vim/after/syntax/doxygen.vim

@@ -1,32 +1,27 @@
 syn keyword doxygenParam contained tparam nextgroup=doxygenParamName,doxygenParamDirection skipwhite
 
-syn region doxygenBody contained start=+\(/\*[*!]\)\@<!<\|[^<]\|$+ matchgroup=doxygenEndComment end=+\*/+re=e-2,me=e-2 contains=doxygenContinueCommentWhite,doxygenTODO,doxygenSpecial,doxygenOtherTags,doxygenSmallSpecial,doxygenHyperLink,doxygenHashLink,@doxygenHtmlGroup,@Spell,doxygenFixedWidth
 
-syn region doxygenBriefLine contained start=+\<\k+ skip=+^\s*\(\*/\@!\s*\)\=\(\<\|[@\\]\<\([npcbea]\>\|em\>\|ref\|link\>\>\|f\$\|[$\\&<>#]\)\|[^ \t\\@*]\)+ end=+^+ contains=doxygenFixedWidth skipwhite keepend matchgroup=xxx
 
 " Permit Ticked parameters
-syn match doxygenParamName contained +`[A-Za-z0-9_:]\+`+ nextgroup=doxygenSpecialMultilineDesc,doxygenSpecialSingleLineDesc
 
-" Too Recursive
+if exists("b:current_syntax")
-" syn al @cxxInDoxygen syntax/cpp.vim
+  unlet b:current_syntax
+endif
 
 " Make all C++ code in a doxygen block look kinda like natural C++
 "syn match doxygenSpecialMultilineDesc "`"
 
-syn match doxygenCommentPreprocHighlight " \+\* " contained
+syn cluster doxyNestedCXX contains=@cxxInDoxygen,doxygenSpecialContinueComment,doxygenSpecialContinueCommentWhite
 
-syn region doxygenFixedWidth matchgroup=Comment start=+`+ skip=+ * + end=+`+ contained contains=cxxObjects,cxxMetaFunction,cxxConstants,cppStatement,cxxExceptionNames,cxxErrorNames,cxxCast,cxxStlPrefix,cxxStlTypes,cxxStlService,cxxStlKeywords,cxxStlFunctions,cxxStlTraits,cxxStlExceptionNames,cxxStlDangerousFunction,cppAccess,cppModifier,cppType,cppExceptions,cppOperator,cppCast,cppStorageClass,cppStructure,cppBoolean,cppConstant,cppModifier,cppRawString,cppNumber,cppRawStringDelimiter,cStatement,cLabel,cRepeat,cTodo,cBadContinuation,cSpecial,cFormat,cString,cCppString,cCppSkip,cStringGroup,cCharacter,cSpecialCharacter,cBlock,cParenGroup,cParen,cCppParen,cBadBlock,cNumber,cNumbers,cNumbersCom,cOctal,cOctalZero,cFloat,cOctalError,cCommentSkip,cCommentL,cCommentString,cComment2String,cComment,cOperator,cStatement,cStructure,cStorageClass,cConstant,cBitField,cUserCont,cPreProcGroup,doxygenCommentPreprocHighlight,cDefine,cNamedConstant
+syn region doxygenFixedWidth containedin=doxygenBody matchgroup=Comment start=+^[ 	]*\** *@code$+ skip=+^\n+ keepend end=+^[ 	]*\** *@endcode$+ contains=@doxyNestedCXX
 
-"syn region doxygenFixedWidth start=+`+ skip=+ * + end=+`+ contained contains=@cxx,@cpp
+syn region doxygenFixedWidth containedin=doxygenBody matchgroup=Comment start=+^[ 	]*\** *\~\~\~$+ skip=+^\n+ end=+^[   ]*\** *\~\~\~$+ contains=@doxyNestedCXX
 
-syn region doxygenFixedWidth start=+\~\~\~+ skip=+ * + end=+\~\~\~+ contained contains=cxxObjects,cxxMetaFunction,cxxConstants,cppStatement,cxxExceptionNames,cxxErrorNames,cxxCast,cxxStlPrefix,cxxStlTypes,cxxStlService,cxxStlKeywords,cxxStlFunctions,cxxStlTraits,cxxStlExceptionNames,cxxStlDangerousFunction,cppAccess,cppModifier,cppType,cppExceptions,cppOperator,cppCast,cppStorageClass,cppStructure,cppBoolean,cppConstant,cppModifier,cppRawString,cppNumber,cppRawStringDelimiter,cStatement,cLabel,cRepeat,cTodo,cBadContinuation,cSpecial,cFormat,cString,cCppString,cCppSkip,cStringGroup,cCharacter,cSpecialCharacter,cBlock,cParenGroup,cParen,cCppParen,cBadBlock,cNumber,cNumbers,cNumbersCom,cOctal,cOctalZero,cFloat,cOctalError,cCommentSkip,cCommentL,cCommentString,cComment2String,cComment,cOperator,cStatement,cStructure,cStorageClass,cConstant,cBitField,cUserCont,cPreProc,cPreProcGroup,doxygenCommentPreprocHighlight,cDefine,cNamedConstant
 
-"syn region doxygenFixedWidth start=+\~\~\~+ skip=+ * + end=+\~\~\~+ contained contains=@cxx,@cpp
+syn region doxygenFixedWidth containedin=doxygenBody matchgroup=Comment start=+`+ end=+`+ keepend contains=@doxyNestedCXX
 
 "syn match doxygenFixedWidth +`.\+`+ contained
 
-syn region doxygenSpecialMultilineDesc  start=+.\++ skip=+^\s*\(\*/\@!\s*\)\=\(\<\|[@\\]\<\([npcbea]\>\|em\>\|ref\|link\>\>\|f\$\|[$\\&<>#]\)\|[^ \t\\@*]\)+ end=+^+ contained contains=doxygenSpecialContinueCommentWhite,doxygenSmallSpecial,doxygenHyperLink,doxygenHashLink,doxygenFixedWidth,@doxygenHtmlGroup,@Spell  skipwhite keepend
-syn region doxygenSpecialSingleLineDesc  start=+.\++ skip=+^\s*\(\*/\@!\s*\)\=\(\<\|[@\\]\<\([npcbea]\>\|em\>\|ref\|link\>\>\|f\$\|[$\\&<>#]\)\|[^ \t\\@*]\)+ end=+^+ contained contains=doxygenOtherTags,doxygenSpecialContinueCommentWhite,doxygenSmallSpecial,doxygenHyperLink,doxygenFixedWidth,doxygenHashLink,@doxygenHtmlGroup,doxygenTODO,@Spell  skipwhite keepend
 
 "syn keyword doxygenOther contained : nextgroup=doxygenSpecialMultilineDesc skipwhite
 
@@ -35,6 +30,3 @@ syn region doxygenSpecialSingleLineDesc  start=+.\++ skip=+^\s*\(\*/\@!\s*\)\=\(
 " +\(\<[npcbea]\>\|\<em\>\|\<ref\|\<link\>\>\|\<f\$\|[$\\&<>#]\)\@!+ nextgroup=doxygenParam,doxygenRetval,doxygenBriefWord,doxygenBold,doxygenBOther,doxygenOther,doxygenOtherTODO,doxygenOtherWARN,doxygenOtherBUG,doxygenPage,doxygenGroupDefine,doxygenCodeRegion,doxygenVerbatimRegion,doxygenDotRegion
 
 hi link doxygenFixedWidth None
-hi link doxygenOtherTags doxygenOther
-hi link doxygenSpecialSingleLineDesc doxygenSpecialMultilineDesc
-hi link doxygenCommentPreprocHighlight PreProc

vim/filetype.vim

@@ -1,14 +1,14 @@
 " Cynlib
 " .cc and .cpp files can be C++ or Cynlib.
 au BufNewFile,BufRead *.cc
-	\ if exists("cynlib_syntax_for_cc")|setf cynlib|else|setf cplusplus|endif
+	\ if exists("cynlib_syntax_for_cc")|setf cynlib|else|set filetype=cpp.cplusplus|endif
 au BufNewFile,BufRead *.cpp
-	\ if exists("cynlib_syntax_for_cpp")|setf cynlib|else|setf cplusplus|endif
+	\ if exists("cynlib_syntax_for_cpp")|setf cynlib|else|set filetype=cpp.cplusplus|endif
 
 " C++
-au BufNewFile,BufRead *.cxx,*.c++,*.hh,*.hxx,*.hpp,*.ipp,*.moc,*.tcc,*.inl setf cplusplus
+au BufNewFile,BufRead *.cxx,*.c++,*.hh,*.hxx,*.hpp,*.ipp,*.moc,*.tcc,*.inl set filetype=cpp.cplusplus
 if has("fname_case")
-  au BufNewFile,BufRead *.C,*.H setf cplusplus
+  au BufNewFile,BufRead *.C,*.H set filetype=cpp.cplusplus
 endif
 
 function! CheckForADAM()
@@ -23,13 +23,13 @@ function! CheckForADAM()
   elseif exists("g:ch_syntax_for_h")
     setf ch
   else
-    setf cplusplus
+    setf cpp.cplusplus
   endif
 endfunction
 
 " .h files can be C, Ch C++, ObjC or ObjC++.
 " Set c_syntax_for_h if you want C, ch_syntax_for_h if you want Ch. ObjC is
 " detected automatically.
-au BufNewFile,BufRead *.h			setf cplusplus "call CheckForADAM()
+au BufNewFile,BufRead *.h			setf cpp.cplusplus "call CheckForADAM()
-au BufNewFile,BufRead		*.cxx,*.cpp,*.hpp,*.cc,*.h		setf cplusplus
+au BufNewFile,BufRead		*.cxx,*.cpp,*.hpp,*.cc,*.h		setf cpp.cplusplus