From 63074a52ad63ff83933fa05afd936abfc7b1646a Mon Sep 17 00:00:00 2001
From: tyru <tyru.exe@gmail.com>
Date: Sat, 23 Jan 2016 02:04:16 +0900
Subject: [PATCH] Avoid E403 error on :syn-include

Example .vimrc:

        let g:markdown_fenced_languages = ['vim', 'viml=vim']
        syntax on

causes

        "/tmp/test.mkd" 6L, 98C
        Error detected while processing /usr/share/vim/vim74/syntax/vim.vim:
        line  777:
        E403: syntax sync: line continuations pattern specified twice
        E403: syntax sync: line continuations pattern specified twice

Example "test.mkd" file:

        ```vim
        echo 'hi'
        ```
---
 syntax/markdown.vim | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/syntax/markdown.vim b/syntax/markdown.vim
index 925f906..6aff90a 100644
--- a/syntax/markdown.vim
+++ b/syntax/markdown.vim
@@ -18,14 +18,20 @@ unlet! b:current_syntax
 if !exists('g:markdown_fenced_languages')
   let g:markdown_fenced_languages = []
 endif
+let s:done_include = {}
 for s:type in map(copy(g:markdown_fenced_languages),'matchstr(v:val,"[^=]*$")')
+  if has_key(s:done_include, matchstr(s:type,'[^.]*'))
+    continue
+  endif
   if s:type =~ '\.'
     let b:{matchstr(s:type,'[^.]*')}_subtype = matchstr(s:type,'\.\zs.*')
   endif
   exe 'syn include @markdownHighlight'.substitute(s:type,'\.','','g').' syntax/'.matchstr(s:type,'[^.]*').'.vim'
   unlet! b:current_syntax
+  let s:done_include[matchstr(s:type,'[^.]*')] = 1
 endfor
 unlet! s:type
+unlet! s:done_include
 
 syn sync minlines=10
 syn case ignore
@@ -91,10 +97,16 @@ syn match markdownFootnote "\[^[^\]]\+\]"
 syn match markdownFootnoteDefinition "^\[^[^\]]\+\]:"
 
 if main_syntax ==# 'markdown'
+  let s:done_include = {}
   for s:type in g:markdown_fenced_languages
+    if has_key(s:done_include, matchstr(s:type,'[^.]*'))
+      continue
+    endif
     exe 'syn region markdownHighlight'.substitute(matchstr(s:type,'[^=]*$'),'\..*','','').' matchgroup=markdownCodeDelimiter start="^\s*```*\s*'.matchstr(s:type,'[^=]*').'\>.*$" end="^\s*```*\ze\s*$" keepend contains=@markdownHighlight'.substitute(matchstr(s:type,'[^=]*$'),'\.','','g')
+    let s:done_include[matchstr(s:type,'[^.]*')] = 1
   endfor
   unlet! s:type
+  unlet! s:done_include
 endif
 
 syn match markdownEscape "\\[][\\`*_{}()<>#+.!-]"