Add option for clang based syntax highlight (#2744)

* Add option for clang based syntax highlight

* Update cn doc

autoload/SpaceVim/layers/lang/c.vim

@@ -69,6 +69,8 @@ function! SpaceVim#layers#lang#c#plugins() abort
       call add(plugins, ['Rip-Rip/clang_complete'])
     endif
   endif
+
+  if s:enable_clang_syntax
     " chromatica is for neovim with py3
     " clamp is for neovim rpcstart('python', " [s:script_folder_path.'/../python/engine.py'])]
     " clighter8 is for vim8
@@ -84,6 +86,9 @@ function! SpaceVim#layers#lang#c#plugins() abort
     else
       call add(plugins, ['bbchung/clighter', { 'if' : has('python')}])
     endif
+  else
+    call add(plugins, ['octol/vim-cpp-enhanced-highlight', { 'merged' : 0}])
+  endif
   return plugins
 endfunction
 
@@ -118,6 +123,8 @@ function! SpaceVim#layers#lang#c#config() abort
   call add(g:spacevim_project_rooter_patterns, '.clang')
 endfunction
 
+let s:enable_clang_syntax = 0
+
 function! SpaceVim#layers#lang#c#set_variable(var) abort
   if has_key(a:var, 'clang_executable')
     let g:completor_clang_binary = a:var.clang_executable
@@ -133,6 +140,8 @@ function! SpaceVim#layers#lang#c#set_variable(var) abort
     let g:asyncomplete_clang_libclang_path = a:var.libclang_path
     let g:clamp_libclang_file = a:var.libclang_path
   endif
+
+  let s:enable_clang_syntax = get(a:var, 'enable_clang_syntax_highlight', s:enable_clang_syntax)
 endfunction
 
 function! s:language_specified_mappings() abort

docs/cn/layers/lang/c.md

@@ -37,6 +37,10 @@ lang: cn
 
 ## 模块配置
 
+- `enable_clang_syntax_highlight` (布尔)
+
+设置是否启用基于 clang 的语法高亮。默认并未开启，开启该功能需要 vim8 或者 neovim。
+
 - `clang_executable`（字符串）
 
 设置可执行程序 clang 的路径。

docs/layers/lang/c.md

@@ -36,6 +36,10 @@ To use this configuration layer, update custom configuration file with:
 
 ## Configuration
 
+- `enable_clang_syntax_highlight` (boolean)
+
+Enable/Disable clang based syntax highlighting.
+
 - `clang_executable` (string)
 
 Set the path to the clang executable