syntastic/syntax_checkers/c.vim

"============================================================================
"File:        c.vim
"Description: Syntax checking plugin for syntastic.vim
"Maintainer:  Gregor Uhlenheuer <kongo2002 at gmail dot com>
"License:     This program is free software. It comes without any warranty,
"             to the extent permitted by applicable law. You can redistribute
"             it and/or modify it under the terms of the Do What The Fuck You
"             Want To Public License, Version 2, as published by Sam Hocevar.
"             See http://sam.zoy.org/wtfpl/COPYING for more details.
"
"============================================================================

" in order to also check header files add this to your .vimrc:
" (this usually creates a .gch file in your source directory)
"
"   let g:syntastic_c_check_header = 1

if exists('loaded_c_syntax_checker')
    finish
endif
let loaded_c_syntax_checker = 1

if !executable('gcc')
    finish
endif

" initialize handlers
function! s:Init()
    let s:handlers = []
    call s:RegHandler('\%(gtk\|glib\)', s:CheckGtk())
    call s:RegHandler('ruby', s:CheckRuby())

    unlet! s:RegHandler
endfunction

function! SyntaxCheckers_c_GetLocList()
    let makeprg = 'gcc -fsyntax-only %'
    let errorformat =  '%-G%f:%s:,%f:%l: %m'

    if expand('%') =~? '.h$'
        if exists('g:syntastic_c_check_header')
            let makeprg = 'gcc -c %'
        else
            return []
        endif
    endif

    let makeprg .= s:SearchHeaders(s:handlers)

    return SyntasticMake({ 'makeprg': makeprg, 'errorformat': errorformat })
endfunction

" search the first 100 lines for include statements that are
" given in the s:handlers dictionary
function! s:SearchHeaders(handlers)
    let includes = ''
    let l:handlers = copy(a:handlers)
    let files = []

    " search current buffer
    for i in range(100)
        for handler in l:handlers
            let line = getline(i)
            if line =~? '^#include.*' . handler["regex"]
                let includes .= handler["func"]
                call remove(l:handlers, index(l:handlers, handler))
            elseif line =~? '^#include\s\+"\S\+"'
                call add(files, matchstr(line, '^#include\s\+"\zs\S\+\ze"'))
            endif
        endfor
    endfor

    " search included headers
    for hfile in files
        if hfile != ''
            let filename = expand('%:p:h') . ((has('win32') || has('win64')) ?
                        \ '\' : '/') . hfile
            try
                let lines = readfile(filename, '', 100)
            catch /E484/
                continue
            endtry
            for line in lines
                for handler in l:handlers
                    if line =~? '^#include.*' . handler["regex"]
                        let includes .= handler["func"]
                        call remove(l:handlers, index(l:handlers, handler))
                    endif
                endfor
            endfor
        endif
    endfor

    return includes
endfunction

" try to find the gtk headers with 'pkg-config'
function! s:CheckGtk()
    if executable('pkg-config')
        if !exists('s:gtk_flags')
            let s:gtk_flags = system('pkg-config --cflags gtk+-2.0')
            let s:gtk_flags = substitute(s:gtk_flags, "\n", '', '')
            let s:gtk_flags = ' ' . s:gtk_flags
        endif
        return s:gtk_flags
    endif
    return ''
endfunction

" try to find the headers with 'rbconfig'
function! s:CheckRuby()
    if executable('ruby')
        if !exists('s:ruby_flags')
            let s:ruby_flags = system('ruby -r rbconfig -e '
                        \ . '''puts Config::CONFIG["archdir"]''')
            let s:ruby_flags = substitute(s:ruby_flags, "\n", '', '')
            let s:ruby_flags = ' -I' . s:ruby_flags
        endif
        return s:ruby_flags
    endif
    return ''
endfunction

" return a handler dictionary object
function! s:RegHandler(regex, function)
    let handler = {}
    let handler["regex"] = a:regex
    let handler["func"] = a:function
    call add(s:handlers, handler)
endfunction

call s:Init()