Fix cflags parsing (#2510, #2265) (#2590)

* Parse CFLAGS that can be passed using a whitelist

I went through GCC's man page and selected flags that can safely be
passed to GCC and that can be useful to syntax checking. These include:

- -I/-i* include flags
- preprocessor flags such as -D
- -W* warning flags
- -O* optimization flags
- most -f options
- -m arch dependent options

* Fix CFLAGS tests: -Idir is now parsed to -I dir
* Added two tests for flags we want or don't want to pass.
* Also check for / in addition to s:sep

2 files changed, 199 insertions, 94 deletions

diff --git a/autoload/ale/c.vim b/autoload/ale/c.vim
index 2d2083da..5540ec14 100644
--- a/autoload/ale/c.vim
+++ b/autoload/ale/c.vim
@@ -28,76 +28,107 @@ function! ale#c#GetBuildDirectory(buffer) abort
     return ale#path#Dirname(l:json_file)
 endfunction
 
-function! ale#c#AreSpecialCharsBalanced(option) abort
-    " Escape \"
-    let l:option_escaped = substitute(a:option, '\\"', '', 'g')
-
-    " Retain special chars only
-    let l:special_chars = substitute(l:option_escaped, '[^"''()`]', '', 'g')
-    let l:special_chars = split(l:special_chars, '\zs')
-
-    " Check if they are balanced
+function! ale#c#ShellSplit(line) abort
     let l:stack = []
+    let l:args = ['']
+    let l:prev = ''
 
-    for l:char in l:special_chars
-        if l:char is# ')'
-            if len(l:stack) == 0 || get(l:stack, -1) isnot# '('
-                return 0
+    for l:char in split(a:line, '\zs')
+        if l:char is# ''''
+            if len(l:stack) > 0 && get(l:stack, -1) is# ''''
+                call remove(l:stack, -1)
+            elseif (len(l:stack) == 0 || get(l:stack, -1) isnot# '"') && l:prev isnot# '\'
+                call add(l:stack, l:char)
             endif
-
-            call remove(l:stack, -1)
-        elseif l:char is# '('
-            call add(l:stack, l:char)
-        else
+        elseif (l:char is# '"' || l:char is# '`') && l:prev isnot# '\'
             if len(l:stack) > 0 && get(l:stack, -1) is# l:char
                 call remove(l:stack, -1)
-            else
+            elseif len(l:stack) == 0 || get(l:stack, -1) isnot# ''''
                 call add(l:stack, l:char)
             endif
+        elseif (l:char is# '(' || l:char is# '[' || l:char is# '{') && l:prev isnot# '\'
+            if len(l:stack) == 0 || get(l:stack, -1) isnot# ''''
+                call add(l:stack, l:char)
+            endif
+        elseif (l:char is# ')' || l:char is# ']' || l:char is# '}') && l:prev isnot# '\'
+            if len(l:stack) > 0 && get(l:stack, -1) is# {')': '(', ']': '[', '}': '{'}[l:char]
+                call remove(l:stack, -1)
+            endif
+        elseif l:char is# ' ' && len(l:stack) == 0
+            if len(get(l:args, -1)) > 0
+                call add(l:args, '')
+            endif
+
+            continue
         endif
+
+        let l:args[-1] = get(l:args, -1) . l:char
     endfor
 
-    return len(l:stack) == 0
+    return l:args
 endfunction
 
 function! ale#c#ParseCFlags(path_prefix, cflag_line) abort
-    let l:split_lines = split(a:cflag_line)
+    let l:cflags_list = []
+
+    let l:split_lines = ale#c#ShellSplit(a:cflag_line)
     let l:option_index = 0
 
     while l:option_index < len(l:split_lines)
-        let l:next_option_index = l:option_index + 1
-
-        " Join space-separated option
-        while l:next_option_index < len(l:split_lines)
-        \&& stridx(l:split_lines[l:next_option_index], '-') != 0
-            let l:next_option_index += 1
-        endwhile
-
-        let l:option = join(l:split_lines[l:option_index : l:next_option_index-1], ' ')
-        call remove(l:split_lines, l:option_index, l:next_option_index-1)
-        call insert(l:split_lines, l:option, l:option_index)
-
-        " Ignore invalid or conflicting options
-        if stridx(l:option, '-') != 0
-        \|| stridx(l:option, '-o') == 0
-        \|| stridx(l:option, '-c') == 0
-            call remove(l:split_lines, l:option_index)
-            let l:option_index = l:option_index - 1
-        " Fix relative path
-        elseif stridx(l:option, '-I') == 0
-            if !(stridx(l:option, ':') == 2+1 || stridx(l:option, '/') == 2+0)
-                let l:option = '-I' . a:path_prefix . s:sep . l:option[2:]
-                call remove(l:split_lines, l:option_index)
-                call insert(l:split_lines, l:option, l:option_index)
+        let l:option = l:split_lines[l:option_index]
+        let l:option_index = l:option_index + 1
+
+        " Include options, that may need relative path fix
+        if stridx(l:option, '-I') == 0
+        \ || stridx(l:option, '-iquote') == 0
+        \ || stridx(l:option, '-isystem') == 0
+        \ || stridx(l:option, '-idirafter') == 0
+            if stridx(l:option, '-I') == 0 && l:option isnot# '-I'
+                let l:arg = join(split(l:option, '\zs')[2:], '')
+                let l:option = '-I'
+            else
+                let l:arg = l:split_lines[l:option_index]
+                let l:option_index = l:option_index + 1
             endif
-        endif
 
-        let l:option_index = l:option_index + 1
-    endwhile
+            " Fix relative paths if needed
+            if stridx(l:arg, s:sep) != 0 && stridx(l:arg, '/') != 0
+                let l:rel_path = substitute(l:arg, '"', '', 'g')
+                let l:rel_path = substitute(l:rel_path, '''', '', 'g')
+                let l:arg = ale#Escape(a:path_prefix . s:sep . l:rel_path)
+            endif
+
+            call add(l:cflags_list, l:option)
+            call add(l:cflags_list, l:arg)
+        " Options with arg that can be grouped with the option or separate
+        elseif stridx(l:option, '-D') == 0 || stridx(l:option, '-B') == 0
+            call add(l:cflags_list, l:option)
 
-    call uniq(l:split_lines)
+            if l:option is# '-D' || l:option is# '-B'
+                call add(l:cflags_list, l:split_lines[l:option_index])
+                let l:option_index = l:option_index + 1
+            endif
+        " Options that have an argument (always separate)
+        elseif l:option is# '-iprefix' || stridx(l:option, '-iwithprefix') == 0
+        \ || l:option is# '-isysroot' || l:option is# '-imultilib'
+            call add(l:cflags_list, l:option)
+            call add(l:cflags_list, l:split_lines[l:option_index])
+            let l:option_index = l:option_index + 1
+        " Options without argument
+        elseif (stridx(l:option, '-W') == 0 && stridx(l:option, '-Wa,') != 0 && stridx(l:option, '-Wl,') != 0 && stridx(l:option, '-Wp,') != 0)
+        \ || l:option is# '-w' || stridx(l:option, '-pedantic') == 0
+        \ || l:option is# '-ansi' || stridx(l:option, '-std=') == 0
+        \ || (stridx(l:option, '-f') == 0 && stridx(l:option, '-fdump') != 0 && stridx(l:option, '-fdiagnostics') != 0 && stridx(l:option, '-fno-show-column') != 0)
+        \ || stridx(l:option, '-O') == 0
+        \ || l:option is# '-C' || l:option is# '-CC' || l:option is# '-trigraphs'
+        \ || stridx(l:option, '-nostdinc') == 0 || stridx(l:option, '-iplugindir=') == 0
+        \ || stridx(l:option, '--sysroot=') == 0 || l:option is# '--no-sysroot-suffix'
+        \ || stridx(l:option, '-m') == 0
+            call add(l:cflags_list, l:option)
+        endif
+    endwhile
 
-    return join(l:split_lines, ' ')
+    return join(l:cflags_list, ' ')
 endfunction
 
 function! ale#c#ParseCFlagsFromMakeOutput(buffer, make_output) abort
diff --git a/test/test_c_flag_parsing.vader b/test/test_c_flag_parsing.vader
index 045554a3..8ae6f9dc 100644
--- a/test/test_c_flag_parsing.vader
+++ b/test/test_c_flag_parsing.vader
@@ -14,7 +14,7 @@ Execute(The CFlags parser should be able to parse include directives):
   call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
 
   AssertEqual
-  \ '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'),
+  \ '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
   \ ale#c#ParseCFlagsFromMakeOutput(bufnr(''), ['gcc -Isubdir -c file.c'])
 
   AssertEqual
@@ -25,14 +25,14 @@ Execute(ParseCFlags should ignore -c and -o):
   call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
 
   AssertEqual
-  \ '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'),
+  \ '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
   \ ale#c#ParseCFlagsFromMakeOutput(bufnr(''), ['gcc -Isubdir -c file.c -o a.out'])
 
 Execute(The CFlags parser should be able to parse macro directives):
   call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
 
   AssertEqual
-  \ '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
+  \ '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
   \   . ' -DTEST=1',
   \ ale#c#ParseCFlagsFromMakeOutput(bufnr(''), ['gcc -Isubdir -DTEST=1 -c file.c'])
 
@@ -40,7 +40,7 @@ Execute(The CFlags parser should be able to parse macro directives with spaces):
   call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
 
   AssertEqual
-  \ '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
+  \ '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
   \   . ' -DTEST=$(( 2 * 4 ))',
   \ ale#c#ParseCFlagsFromMakeOutput(bufnr(''), ['gcc -Isubdir -DTEST=$(( 2 * 4 )) -c file.c'])
 
@@ -48,14 +48,14 @@ Execute(The CFlags parser should be able to parse shell directives with spaces):
   call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
 
   AssertEqual
-  \ '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
+  \ '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
   \   .  ' -DTEST=`date +%s`',
   \ ale#c#ParseCFlagsFromMakeOutput(bufnr(''), ['gcc -Isubdir -DTEST=`date +%s` -c file.c'])
 
 Execute(ParseCFlags should be able to parse flags with relative paths):
   AssertEqual
-  \ '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')
+  \ '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include'))
   \   . ' -DTEST=`date +%s`',
   \ ale#c#ParseCFlags(
   \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
@@ -67,8 +67,8 @@ Execute(ParseCFlags should be able to parse flags with relative paths):
 Execute(ParseCFlags should be able to parse -Dgoal):
   AssertEqual
   \ '-Dgoal=9'
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include'))
   \   . ' -DTEST=`date +%s`',
   \ ale#c#ParseCFlags(
   \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
@@ -77,16 +77,30 @@ Execute(ParseCFlags should be able to parse -Dgoal):
   \     . ' -DTEST=`date +%s` -c file.c'
   \ )
 
+Execute(ParseCFlags should ignore -T and other arguments):
+  AssertEqual
+  \ '-Dgoal=9'
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . '--sysroot=subdir'
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include'))
+  \   . ' -DTEST=`date +%s`',
+  \ ale#c#ParseCFlags(
+  \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
+  \   'gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir --sysroot=subdir '
+  \     .  '-I'. ale#path#Simplify('kernel/include')
+  \     .  ' -DTEST=`date +%s` -c file.c'
+  \ )
+
 Execute(ParseCFlags should handle paths with spaces in double quotes):
   AssertEqual
   \ '-Dgoal=9'
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/"dir with spaces"')
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include'))
   \   . ' -DTEST=`date +%s`',
   \ ale#c#ParseCFlags(
   \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \   'gcc -Dgoal=9 -Isubdir '
+  \   'gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir '
   \     . '-I"dir with spaces"' . ' -I'. ale#path#Simplify('kernel/include')
   \     . ' -DTEST=`date +%s` -c file.c'
   \ )
@@ -94,28 +108,29 @@ Execute(ParseCFlags should handle paths with spaces in double quotes):
 Execute(ParseCFlags should handle paths with spaces in single quotes):
   AssertEqual
   \ '-Dgoal=9'
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. "/test_c_projects/makefile_project/'dir with spaces'")
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include'))
   \   . ' -DTEST=`date +%s`',
   \ ale#c#ParseCFlags(
   \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \   'gcc -Dgoal=9 -Isubdir '
-  \     . "-I'dir with spaces'" . ' -I'. ale#path#Simplify('kernel/include')
+  \   'gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir '
+  \     . '-I''dir with spaces''' . ' -I'. ale#path#Simplify('kernel/include')
   \     . ' -DTEST=`date +%s` -c file.c'
   \ )
 
 Execute(ParseCFlags should handle paths with minuses):
   AssertEqual
   \ '-Dgoal=9'
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash')
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include'))
   \   . ' -DTEST=`date +%s`',
   \ ale#c#ParseCFlags(
   \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \   'gcc -Dgoal=9 -Isubdir '
-  \     . ' -Idir-with-dash'
+  \   'gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir '
+  \     . '-I''dir with spaces''' . ' -Idir-with-dash'
   \     . ' -I'. ale#path#Simplify('kernel/include')
   \     . ' -DTEST=`date +%s` -c file.c'
   \ )
@@ -123,14 +138,17 @@ Execute(ParseCFlags should handle paths with minuses):
 Execute(ParseCFlags should handle -D with minuses):
   AssertEqual
   \ '-Dgoal=9'
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
   \   . ' -Dmacro-with-dash'
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include'))
   \   . ' -DTEST=`date +%s`',
   \ ale#c#ParseCFlags(
   \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \   'gcc -Dgoal=9 -Isubdir '
+  \   'gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir '
   \     . '-Dmacro-with-dash '
+  \     . '-I''dir with spaces''' . ' -Idir-with-dash'
   \     . ' -I'. ale#path#Simplify('kernel/include')
   \     . ' -DTEST=`date +%s` -c file.c'
   \ )
@@ -138,11 +156,16 @@ Execute(ParseCFlags should handle -D with minuses):
 Execute(ParseCFlags should handle flags at the end of the line):
   AssertEqual
   \ '-Dgoal=9'
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')
-  \   . ' ' . '-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include'),
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' -Dmacro-with-dash'
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
   \ ale#c#ParseCFlags(
   \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \   'gcc -Dgoal=9 -Isubdir '
+  \   'gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir '
+  \     . '-Dmacro-with-dash '
+  \     . '-I''dir with spaces''' . ' -Idir-with-dash'
   \     . ' -I'. ale#path#Simplify('kernel/include')
   \ )
 
@@ -156,14 +179,14 @@ Execute(ParseCompileCommandsFlags should parse some basic flags):
   silent noautocmd execute 'file! ' . fnameescape(ale#path#Simplify('/foo/bar/xmms2-mpris/src/xmms2-mpris.c'))
 
   AssertEqual
-  \ '-I/usr/include/xmms2',
+  \ '-I ' . ale#path#Simplify('/usr/include/xmms2'),
   \ ale#c#ParseCompileCommandsFlags(bufnr(''), { "xmms2-mpris.c": [
   \   {
-  \     'directory': '/foo/bar/xmms2-mpris',
-  \     'command': '/usr/bin/cc  -I' . '/usr/include/xmms2'
+  \     'directory': ale#path#Simplify('/foo/bar/xmms2-mpris'),
+  \     'command': '/usr/bin/cc  -I' . ale#path#Simplify('/usr/include/xmms2')
   \       . '    -o CMakeFiles/xmms2-mpris.dir/src/xmms2-mpris.c.o'
-  \       . '   -c ' . '/foo/bar/xmms2-mpris/src/xmms2-mpris.c',
-  \     'file': '/foo/bar/xmms2-mpris/src/xmms2-mpris.c',
+  \       . '   -c ' . ale#path#Simplify('/foo/bar/xmms2-mpris/src/xmms2-mpris.c'),
+  \     'file': ale#path#Simplify('/foo/bar/xmms2-mpris/src/xmms2-mpris.c'),
   \   },
   \ ] }, {})
 
@@ -183,14 +206,14 @@ Execute(ParseCompileCommandsFlags should fall back to files in the same director
   silent noautocmd execute 'file! ' . fnameescape(ale#path#Simplify('/foo/bar/xmms2-mpris/src/xmms2-mpris.c'))
 
   AssertEqual
-  \ '-I/usr/include/xmms2',
+  \ '-I ' . ale#path#Simplify('/usr/include/xmms2'),
   \ ale#c#ParseCompileCommandsFlags(bufnr(''), {}, { "src": [
   \   {
-  \     'directory': '/foo/bar/xmms2-mpris',
-  \     'command': '/usr/bin/cc  -I' . '/usr/include/xmms2'
+  \     'directory': ale#path#Simplify('/foo/bar/xmms2-mpris'),
+  \     'command': '/usr/bin/cc  -I' . ale#path#Simplify('/usr/include/xmms2')
   \       . '    -o CMakeFiles/xmms2-mpris.dir/src/xmms2-mpris.c.o'
-  \       . '   -c ' . '/foo/bar/xmms2-mpris/src/xmms2-mpris.c',
-  \     'file': (has('win32') ? 'C:' : '') . '/foo/bar/xmms2-mpris/src/xmms2-other.c',
+  \       . '   -c ' . ale#path#Simplify('/foo/bar/xmms2-mpris/src/xmms2-mpris.c'),
+  \     'file': ale#path#Simplify((has('win32') ? 'C:' : '') . '/foo/bar/xmms2-mpris/src/xmms2-other.c'),
   \   },
   \ ] })
 
@@ -198,7 +221,7 @@ Execute(ParseCompileCommandsFlags should take commands from matching .c files fo
   silent noautocmd execute 'file! ' . fnameescape(ale#path#Simplify('/foo/bar/xmms2-mpris/src/xmms2-mpris.h'))
 
   AssertEqual
-  \ '-I/usr/include/xmms2',
+  \ '-I /usr/include/xmms2',
   \ ale#c#ParseCompileCommandsFlags(
   \   bufnr(''),
   \   {
@@ -220,7 +243,7 @@ Execute(ParseCompileCommandsFlags should take commands from matching .cpp files
   silent noautocmd execute 'file! ' . fnameescape(ale#path#Simplify('/foo/bar/xmms2-mpris/src/xmms2-mpris.hpp'))
 
   AssertEqual
-  \ '-I/usr/include/xmms2',
+  \ '-I /usr/include/xmms2',
   \ ale#c#ParseCompileCommandsFlags(
   \   bufnr(''),
   \   {
@@ -242,7 +265,7 @@ Execute(ParseCompileCommandsFlags should take commands from matching .cpp files
   silent noautocmd execute 'file! ' . fnameescape(ale#path#Simplify('/foo/bar/xmms2-mpris/src/xmms2-mpris.h'))
 
   AssertEqual
-  \ '-I/usr/include/xmms2',
+  \ '-I /usr/include/xmms2',
   \ ale#c#ParseCompileCommandsFlags(
   \   bufnr(''),
   \   {
@@ -282,13 +305,64 @@ Execute(ParseCompileCommandsFlags should not take commands from .c files for .h
   \   },
   \ )
 
+Execute(ParseCFlags should not merge flags):
+  AssertEqual
+  \ '-Dgoal=9'
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash'))
+  \   . ' ' . '-I' . ' ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
+  \ ale#c#ParseCFlags(
+  \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
+  \   'gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir '
+  \     . 'subdir/somedep1.o ' . 'subdir/somedep2.o '
+  \     . '-I''dir with spaces''' . ' -Idir-with-dash '
+  \     . 'subdir/somedep3.o ' . 'subdir/somedep4.o '
+  \     . ' -I'. ale#path#Simplify('kernel/include') . ' '
+  \     . 'subdir/somedep5.o ' . 'subdir/somedep6.o '
+  \ )
+
 Execute(ParseCFlags should handle parenthesis and quotes):
   AssertEqual
-  \ '-Dgoal=9 -Dtest1="('' '')" file1.o -Dtest2=''(` `)'' file2.o -Dtest3=`(" ")` file3.o',
+  \ '-Dgoal=9 -Dtest1="('' '')" -Dtest2=''(` `)'' -Dtest3=`(" ")`',
   \ ale#c#ParseCFlags(
   \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \   'gcc -Dgoal=9 '
+  \   'gcc -Dgoal=9 -Tlinkerfile.ld blabla '
   \     . '-Dtest1="('' '')" file1.o '
   \     . '-Dtest2=''(` `)'' file2.o '
   \     . '-Dtest3=`(" ")` file3.o '
   \ )
+
+Execute(CFlags we want to pass):
+  AssertEqual
+  \ '-I ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/inc'))
+  \ . ' -I ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/include'))
+  \ . ' -iquote ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/incquote'))
+  \ . ' -isystem ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/incsystem'))
+  \ . ' -idirafter ' . ale#Escape(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/incafter'))
+  \ . ' -Dmacro=value -D macro2 -Bbdir -B bdir2'
+  \ . ' -iprefix prefix -iwithprefix prefix2 -iwithprefixbefore prefix3'
+  \ . ' -isysroot sysroot --sysroot=test --no-sysroot-suffix -imultilib multidir'
+  \ . ' -Wsome-warning -std=c89 -pedantic -pedantic-errors -ansi'
+  \ . ' -foption -O2 -C -CC -trigraphs -nostdinc -nostdinc++'
+  \ . ' -iplugindir=dir -march=native -w',
+  \ ale#c#ParseCFlags(
+  \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
+  \   'gcc'
+  \ . ' -Iinc -I include -iquote incquote -isystem incsystem -idirafter incafter'
+  \ . ' -Dmacro=value -D macro2 -Bbdir -B bdir2'
+  \ . ' -iprefix prefix -iwithprefix prefix2 -iwithprefixbefore prefix3'
+  \ . ' -isysroot sysroot --sysroot=test --no-sysroot-suffix -imultilib multidir'
+  \ . ' -Wsome-warning -std=c89 -pedantic -pedantic-errors -ansi'
+  \ . ' -foption -O2 -C -CC -trigraphs -nostdinc -nostdinc++'
+  \ . ' -iplugindir=dir -march=native -w'
+  \ )
+
+Execute(CFlags we dont want to pass):
+  AssertEqual
+  \ '',
+  \ ale#c#ParseCFlags(
+  \   ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
+  \   'gcc -Wl,option -Wa,option -Wp,option filename.c somelib.a '
+  \ . '-fdump-file=name -fdiagnostics-arg -fno-show-column'
+  \ )