Add support for parsing compile_commands.json files for C compilers

19 files changed, 345 insertions, 239 deletions

diff --git a/ale_linters/c/clang.vim b/ale_linters/c/clang.vim
index ddec4fcb..48ea76dd 100644
--- a/ale_linters/c/clang.vim
+++ b/ale_linters/c/clang.vim
@@ -14,10 +14,10 @@ function! ale_linters#c#clang#GetCommand(buffer, output) abort
     " -iquote with the directory the file is in makes #include work for
     "  headers in the same directory.
     return ale#Escape(ale_linters#c#clang#GetExecutable(a:buffer))
-    \   . ' -S -x c -fsyntax-only '
-    \   . '-iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h')) . ' '
-    \   . l:cflags
-    \   . ale#Var(a:buffer, 'c_clang_options') . ' -'
+    \   . ' -S -x c -fsyntax-only'
+    \   . ' -iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
+    \   . ale#Pad(l:cflags)
+    \   . ale#Pad(ale#Var(a:buffer, 'c_clang_options')) . ' -'
 endfunction
 
 call ale#linter#Define('c', {
diff --git a/ale_linters/c/clangtidy.vim b/ale_linters/c/clangtidy.vim
index 47faa1ef..d456a5a2 100644
--- a/ale_linters/c/clangtidy.vim
+++ b/ale_linters/c/clangtidy.vim
@@ -35,7 +35,7 @@ function! s:GetBuildDirectory(buffer) abort
         return l:build_dir
     endif
 
-    return ale#c#FindCompileCommands(a:buffer)
+    return ale#path#Dirname(ale#c#FindCompileCommands(a:buffer))
 endfunction
 
 function! ale_linters#c#clangtidy#GetCommand(buffer) abort
diff --git a/ale_linters/c/gcc.vim b/ale_linters/c/gcc.vim
index 98563952..63fe87a6 100644
--- a/ale_linters/c/gcc.vim
+++ b/ale_linters/c/gcc.vim
@@ -14,10 +14,10 @@ function! ale_linters#c#gcc#GetCommand(buffer, output) abort
     " -iquote with the directory the file is in makes #include work for
     "  headers in the same directory.
     return ale#Escape(ale_linters#c#gcc#GetExecutable(a:buffer))
-    \   . ' -S -x c -fsyntax-only '
-    \   . '-iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h')) . ' '
-    \   . l:cflags
-    \   . ale#Var(a:buffer, 'c_gcc_options') . ' -'
+    \   . ' -S -x c -fsyntax-only'
+    \   . ' -iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
+    \   . ale#Pad(l:cflags)
+    \   . ale#Pad(ale#Var(a:buffer, 'c_gcc_options')) . ' -'
 endfunction
 
 call ale#linter#Define('c', {
diff --git a/ale_linters/cpp/clang.vim b/ale_linters/cpp/clang.vim
index e8d96187..4f3c5b6f 100644
--- a/ale_linters/cpp/clang.vim
+++ b/ale_linters/cpp/clang.vim
@@ -14,10 +14,10 @@ function! ale_linters#cpp#clang#GetCommand(buffer, output) abort
     " -iquote with the directory the file is in makes #include work for
     "  headers in the same directory.
     return ale#Escape(ale_linters#cpp#clang#GetExecutable(a:buffer))
-    \   . ' -S -x c++ -fsyntax-only '
-    \   . '-iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h')) . ' '
-    \   . l:cflags
-    \   . ale#Var(a:buffer, 'cpp_clang_options') . ' -'
+    \   . ' -S -x c++ -fsyntax-only'
+    \   . ' -iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
+    \   . ale#Pad(l:cflags)
+    \   . ale#Pad(ale#Var(a:buffer, 'cpp_clang_options')) . ' -'
 endfunction
 
 call ale#linter#Define('cpp', {
diff --git a/ale_linters/cpp/clangcheck.vim b/ale_linters/cpp/clangcheck.vim
index a109d5d3..687991bd 100644
--- a/ale_linters/cpp/clangcheck.vim
+++ b/ale_linters/cpp/clangcheck.vim
@@ -16,7 +16,7 @@ function! ale_linters#cpp#clangcheck#GetCommand(buffer) abort
     let l:build_dir = ale#Var(a:buffer, 'c_build_dir')
 
     if empty(l:build_dir)
-        let l:build_dir = ale#c#FindCompileCommands(a:buffer)
+        let l:build_dir = ale#path#Dirname(ale#c#FindCompileCommands(a:buffer))
     endif
 
     " The extra arguments in the command are used to prevent .plist files from
diff --git a/ale_linters/cpp/clangtidy.vim b/ale_linters/cpp/clangtidy.vim
index 1d5fb77a..d683327f 100644
--- a/ale_linters/cpp/clangtidy.vim
+++ b/ale_linters/cpp/clangtidy.vim
@@ -29,7 +29,7 @@ function! s:GetBuildDirectory(buffer) abort
         return l:build_dir
     endif
 
-    return ale#c#FindCompileCommands(a:buffer)
+    return ale#path#Dirname(ale#c#FindCompileCommands(a:buffer))
 endfunction
 
 function! ale_linters#cpp#clangtidy#GetCommand(buffer) abort
diff --git a/ale_linters/cpp/gcc.vim b/ale_linters/cpp/gcc.vim
index a663eaa3..242e389e 100644
--- a/ale_linters/cpp/gcc.vim
+++ b/ale_linters/cpp/gcc.vim
@@ -14,10 +14,10 @@ function! ale_linters#cpp#gcc#GetCommand(buffer, output) abort
     " -iquote with the directory the file is in makes #include work for
     "  headers in the same directory.
     return ale#Escape(ale_linters#cpp#gcc#GetExecutable(a:buffer))
-    \   . ' -S -x c++ -fsyntax-only '
-    \   . '-iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h')) . ' '
-    \   . l:cflags
-    \   . ale#Var(a:buffer, 'cpp_gcc_options') . ' -'
+    \   . ' -S -x c++ -fsyntax-only'
+    \   . ' -iquote ' . ale#Escape(fnamemodify(bufname(a:buffer), ':p:h'))
+    \   . ale#Pad(l:cflags)
+    \   . ale#Pad(ale#Var(a:buffer, 'cpp_gcc_options')) . ' -'
 endfunction
 
 call ale#linter#Define('cpp', {
diff --git a/autoload/ale/c.vim b/autoload/ale/c.vim
index fbfe9509..19bb0d5e 100644
--- a/autoload/ale/c.vim
+++ b/autoload/ale/c.vim
@@ -2,6 +2,7 @@
 " Description: Functions for integrating with C-family linters.
 
 call ale#Set('c_parse_makefile', 0)
+call ale#Set('c_parse_compile_commands', 0)
 let s:sep = has('win32') ? '\' : '/'
 
 " Set just so tests can override it.
@@ -26,11 +27,11 @@ function! ale#c#FindProjectRoot(buffer) abort
     return ''
 endfunction
 
-function! ale#c#ParseCFlagsToList(path_prefix, cflags) abort
+function! ale#c#ParseCFlags(path_prefix, cflag_line) abort
     let l:cflags_list = []
     let l:previous_options = []
 
-    for l:option in a:cflags
+    for l:option in split(a:cflag_line, '-')
         call add(l:previous_options, l:option)
         " Check if cflag contained a '-' and should not have been splitted
         let l:option_list = split(l:option, '\zs')
@@ -62,32 +63,122 @@ function! ale#c#ParseCFlagsToList(path_prefix, cflags) abort
         endif
     endfor
 
-    return l:cflags_list
+    return join(l:cflags_list, ' ')
 endfunction
 
-function! ale#c#ParseCFlags(buffer, stdout_make) abort
+function! ale#c#ParseCFlagsFromMakeOutput(buffer, make_output) abort
     if !g:ale_c_parse_makefile
-        return []
+        return ''
     endif
 
     let l:buffer_filename = expand('#' . a:buffer . ':t')
-    let l:cflags = []
-    for l:lines in split(a:stdout_make, '\\n')
-        if stridx(l:lines, l:buffer_filename) >= 0
-            let l:cflags = split(l:lines, '-')
+    let l:cflag_line = ''
+
+    " Find a line matching this buffer's filename in the make output.
+    for l:line in a:make_output
+        if stridx(l:line, l:buffer_filename) >= 0
+            let l:cflag_line = l:line
             break
         endif
     endfor
 
     let l:makefile_path = ale#path#FindNearestFile(a:buffer, 'Makefile')
-    return ale#c#ParseCFlagsToList(fnamemodify(l:makefile_path, ':p:h'), l:cflags)
+    let l:makefile_dir = fnamemodify(l:makefile_path, ':p:h')
+
+    return ale#c#ParseCFlags(l:makefile_dir, l:cflag_line)
+endfunction
+
+" Given a buffer number, find the build subdirectory with compile commands
+" The subdirectory is returned without the trailing /
+function! ale#c#FindCompileCommands(buffer) abort
+    " Look above the current source file to find compile_commands.json
+    let l:json_file = ale#path#FindNearestFile(a:buffer, 'compile_commands.json')
+
+    if !empty(l:json_file)
+        return l:json_file
+    endif
+
+    " Search in build directories if we can't find it in the project.
+    for l:path in ale#path#Upwards(expand('#' . a:buffer . ':p:h'))
+        for l:dirname in ale#Var(a:buffer, 'c_build_dir_names')
+            let l:c_build_dir = l:path . s:sep . l:dirname
+            let l:json_file = l:c_build_dir . s:sep . 'compile_commands.json'
+
+            if filereadable(l:json_file)
+                return l:json_file
+            endif
+        endfor
+    endfor
+
+    return ''
+endfunction
+
+" Cache compile_commands.json data in a Dictionary, so we don't need to read
+" the same files over and over again. The key in the dictionary will include
+" the last modified time of the file.
+if !exists('s:compile_commands_cache')
+    let s:compile_commands_cache = {}
+endif
+
+function! s:GetListFromCompileCommandsFile(compile_commands_file) abort
+    if empty(a:compile_commands_file)
+        return []
+    endif
+
+    let l:time = getftime(a:compile_commands_file)
+
+    if l:time < 0
+        return []
+    endif
+
+    let l:key = a:compile_commands_file . ':' . l:time
+
+    if has_key(s:compile_commands_cache, l:key)
+        return s:compile_commands_cache[l:key]
+    endif
+
+    let l:data = []
+    silent! let l:data = json_decode(join(readfile(a:compile_commands_file), ''))
+
+    if !empty(l:data)
+        let s:compile_commands_cache[l:key] = l:data
+
+        return l:data
+    endif
+
+    return []
+endfunction
+
+function! ale#c#ParseCompileCommandsFlags(buffer, dir, json_list) abort
+    for l:item in a:json_list
+        if bufnr(l:item.file) is a:buffer
+            return ale#c#ParseCFlags(a:dir, l:item.command)
+        endif
+    endfor
+
+    return ''
+endfunction
+
+function! ale#c#FlagsFromCompileCommands(buffer, compile_commands_file) abort
+    let l:dir = ale#path#Dirname(a:compile_commands_file)
+    let l:json_list = s:GetListFromCompileCommandsFile(a:compile_commands_file)
+
+    return ale#c#ParseCompileCommandsFlags(a:buffer, l:dir, l:json_list)
 endfunction
 
 function! ale#c#GetCFlags(buffer, output) abort
     let l:cflags = ' '
 
-    if g:ale_c_parse_makefile && !empty(a:output)
-        let l:cflags = join(ale#c#ParseCFlags(a:buffer, join(a:output, '\n')), ' ') . ' '
+    if ale#Var(a:buffer, 'c_parse_makefile') && !empty(a:output)
+        let l:cflags = ale#c#ParseCFlagsFromMakeOutput(a:buffer, a:output)
+    endif
+
+    if ale#Var(a:buffer, 'c_parse_compile_commands')
+        let l:json_file = ale#c#FindCompileCommands(a:buffer)
+
+        if !empty(l:json_file)
+            let l:cflags = ale#c#FlagsFromCompileCommands(a:buffer, l:json_file)
+        endif
     endif
 
     if l:cflags is# ' '
@@ -98,8 +189,9 @@ function! ale#c#GetCFlags(buffer, output) abort
 endfunction
 
 function! ale#c#GetMakeCommand(buffer) abort
-    if g:ale_c_parse_makefile
+    if ale#Var(a:buffer, 'c_parse_makefile')
         let l:makefile_path = ale#path#FindNearestFile(a:buffer, 'Makefile')
+
         if !empty(l:makefile_path)
             return 'cd '. fnamemodify(l:makefile_path, ':p:h') . ' && make -n'
         endif
@@ -161,19 +253,3 @@ let g:ale_c_build_dir_names = get(g:, 'ale_c_build_dir_names', [
 \   'build',
 \   'bin',
 \])
-
-" Given a buffer number, find the build subdirectory with compile commands
-" The subdirectory is returned without the trailing /
-function! ale#c#FindCompileCommands(buffer) abort
-    for l:path in ale#path#Upwards(expand('#' . a:buffer . ':p:h'))
-        for l:dirname in ale#Var(a:buffer, 'c_build_dir_names')
-            let l:c_build_dir = l:path . s:sep . l:dirname
-
-            if filereadable(l:c_build_dir . '/compile_commands.json')
-                return l:c_build_dir
-            endif
-        endfor
-    endfor
-
-    return ''
-endfunction
diff --git a/autoload/ale/path.vim b/autoload/ale/path.vim
index 45da3709..2d8a6ac7 100644
--- a/autoload/ale/path.vim
+++ b/autoload/ale/path.vim
@@ -105,6 +105,21 @@ function! ale#path#GetAbsPath(base_directory, filename) abort
     return ale#path#Simplify(a:base_directory . l:sep . a:filename)
 endfunction
 
+" Given a path, return the directory name for that path, with no trailing
+" slashes. If the argument is empty(), return an empty string.
+function! ale#path#Dirname(path) abort
+    if empty(a:path)
+        return ''
+    endif
+
+    " For /foo/bar/ we need :h:h to get /foo
+    if a:path[-1:] is# '/'
+        return fnamemodify(a:path, ':h:h')
+    endif
+
+    return fnamemodify(a:path, ':h')
+endfunction
+
 " Given a buffer number and a relative or absolute path, return 1 if the
 " two paths represent the same file on disk.
 function! ale#path#IsBufferPath(buffer, complex_filename) abort
diff --git a/doc/ale-c.txt b/doc/ale-c.txt
index cf837e5e..282dcf94 100644
--- a/doc/ale-c.txt
+++ b/doc/ale-c.txt
@@ -25,13 +25,28 @@ g:ale_c_build_dir                                           *g:ale_c_build_dir*
   Type: |String|
   Default: `''`
 
-  A path to the directory containing the `compile_commands.json` file to use
-  with c-family linters. Usually setting this option to a non-empty string
-  will override the |g:ale_c_build_dir_names| option to impose a compilation
-  database (it can be useful if multiple builds are in multiple build
-  subdirectories in the project tree).
-  This feature is also most useful for the clang tools linters, wrapped
-  around LibTooling (namely clang-tidy here)
+  For programs that can read `compile_commands.json` files, this option can be
+  set to the directory containing the file for the project. ALE will try to
+  determine the location of `compile_commands.json` automatically, but if your
+  file exists in some other directory, you can set this option so ALE will
+  know where it is.
+
+  This directory will be searched instead of |g:ale_c_build_dir_names|.
+
+
+g:ale_c_parse_compile_commands                 *g:ale_c_parse_compile_commands*
+                                               *b:ale_c_parse_compile_commands*
+  Type: |Number|
+  Default: `0`
+
+  If set to `1`, ALE will parse `compile_commands.json` files to automatically
+  determine flags for C or C++ compilers. ALE will first search for the
+  nearest `compile_commands.json` file, and then look for
+  `compile_commands.json` files in the directories for
+  |g:ale_c_build_dir_names|.
+
+  If |g:ale_c_parse_makefile| or |b:ale_c_parse_makefile| is set to `1`, the
+  output of `make -n` will be preferred over `compile_commands.json` files.
 
 
 g:ale_c_parse_makefile                                 *g:ale_c_parse_makefile*
diff --git a/doc/ale-cpp.txt b/doc/ale-cpp.txt
index 8bd111e4..be7e840c 100644
--- a/doc/ale-cpp.txt
+++ b/doc/ale-cpp.txt
@@ -10,6 +10,7 @@ The following C options also apply to some C++ linters too.
 * |g:ale_c_build_dir_names|
 * |g:ale_c_build_dir|
 * |g:ale_c_parse_makefile|
+* |g:ale_c_parse_compile_commands|
 
 
 ===============================================================================
diff --git a/test/command_callback/test_c_clang_command_callbacks.vader b/test/command_callback/test_c_clang_command_callbacks.vader
index 87f7fd06..7d2ff0bf 100644
--- a/test/command_callback/test_c_clang_command_callbacks.vader
+++ b/test/command_callback/test_c_clang_command_callbacks.vader
@@ -1,4 +1,7 @@
 Before:
+  Save g:ale_c_parse_makefile
+  let g:ale_c_parse_makefile = 0
+
   call ale#assert#SetUpLinterTest('c', 'clang')
   let b:command_tail = ' -S -x c -fsyntax-only -iquote'
   \   . ' ' . ale#Escape(getcwd())
diff --git a/test/command_callback/test_c_gcc_command_callbacks.vader b/test/command_callback/test_c_gcc_command_callbacks.vader
index 45514051..1f51c3bc 100644
--- a/test/command_callback/test_c_gcc_command_callbacks.vader
+++ b/test/command_callback/test_c_gcc_command_callbacks.vader
@@ -1,4 +1,7 @@
 Before:
+  Save g:ale_c_parse_makefile
+  let g:ale_c_parse_makefile = 0
+
   call ale#assert#SetUpLinterTest('c', 'gcc')
 
   let b:command_tail = ' -S -x c -fsyntax-only -iquote'
diff --git a/test/command_callback/test_cpp_clang_command_callbacks.vader b/test/command_callback/test_cpp_clang_command_callbacks.vader
index 3a5ea945..e96fd8e7 100644
--- a/test/command_callback/test_cpp_clang_command_callbacks.vader
+++ b/test/command_callback/test_cpp_clang_command_callbacks.vader
@@ -1,4 +1,7 @@
 Before:
+  Save g:ale_c_parse_makefile
+  let g:ale_c_parse_makefile = 0
+
   call ale#assert#SetUpLinterTest('cpp', 'clang')
   let b:command_tail = ' -S -x c++ -fsyntax-only -iquote'
   \   . ' ' . ale#Escape(getcwd())
diff --git a/test/command_callback/test_cpp_gcc_command_callbacks.vader b/test/command_callback/test_cpp_gcc_command_callbacks.vader
index f9fad8c8..0a86df4f 100644
--- a/test/command_callback/test_cpp_gcc_command_callbacks.vader
+++ b/test/command_callback/test_cpp_gcc_command_callbacks.vader
@@ -1,4 +1,7 @@
 Before:
+  Save g:ale_c_parse_makefile
+  let g:ale_c_parse_makefile = 0
+
   call ale#assert#SetUpLinterTest('cpp', 'gcc')
   let b:command_tail = ' -S -x c++ -fsyntax-only -iquote'
   \   . ' ' . ale#Escape(getcwd())
diff --git a/test/test_c_flag_parsing.vader b/test/test_c_flag_parsing.vader
new file mode 100644
index 00000000..8bd805df
--- /dev/null
+++ b/test/test_c_flag_parsing.vader
@@ -0,0 +1,161 @@
+Before:
+  Save g:ale_c_parse_makefile
+
+  call ale#test#SetDirectory('/testplugin/test')
+
+  let g:ale_c_parse_makefile = 1
+
+After:
+  Restore
+
+  call ale#test#RestoreDirectory()
+
+Execute(The CFlags parser should be able to parse include directives):
+  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
+
+  AssertEqual
+  \ ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
+  \ ale#c#ParseCFlagsFromMakeOutput(bufnr(''), ['gcc -Isubdir -c file.c'])
+
+Execute(The CFlags parser should be able to parse macro directives):
+  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
+
+  AssertEqual
+  \ ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' -DTEST=1',
+  \ ale#c#ParseCFlagsFromMakeOutput(bufnr(''), ['gcc -Isubdir -DTEST=1 -c file.c'])
+
+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
+  \ ale#Escape('-I' . 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'])
+
+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
+  \ ale#Escape('-I' . 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
+  \ ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . ale#Escape('-I' . 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 -Isubdir  '
+  \     .  '-I'. ale#path#Simplify('kernel/include')
+  \     .  ' -DTEST=`date +%s` -c file.c'
+  \ )
+
+Execute(ParseCFlags should be able to parse -Dgoal):
+  AssertEqual
+  \ '-Dgoal=9'
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . ale#Escape('-I' . 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'. ale#path#Simplify('kernel/include')
+  \     . ' -DTEST=`date +%s` -c file.c'
+  \ )
+
+Execute(ParseCFlags should ignore -T and other arguments):
+  AssertEqual
+  \ '-Dgoal=9'
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . ale#Escape('-I' . 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 '
+  \     .  '-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'
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . ale#Escape('-I' . 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 '
+  \     . '-I"dir with spaces"' . ' -I'. ale#path#Simplify('kernel/include')
+  \     . ' -DTEST=`date +%s` -c file.c'
+  \ )
+
+Execute(ParseCFlags should handle paths with spaces in single quotes):
+  AssertEqual
+  \ '-Dgoal=9'
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . ale#Escape('-I' . 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 '
+  \     . '-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'
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash'))
+  \   . ' ' . ale#Escape('-I' . 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 '
+  \     . '-I''dir with spaces''' . ' -Idir-with-dash'
+  \     . ' -I'. ale#path#Simplify('kernel/include')
+  \     . ' -DTEST=`date +%s` -c file.c'
+  \ )
+
+Execute(ParseCFlags should handle -D with minuses):
+  AssertEqual
+  \ '-Dgoal=9'
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))
+  \   . ' -Dmacro-with-dash'
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces'))
+  \   . ' ' . ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash'))
+  \   . ' ' . ale#Escape('-I' . 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 '
+  \     . '-Dmacro-with-dash '
+  \     . '-I''dir with spaces''' . ' -Idir-with-dash'
+  \     . ' -I'. ale#path#Simplify('kernel/include')
+  \     . ' -DTEST=`date +%s` -c file.c'
+  \ )
+
+Execute(FlagsFromCompileCommands should tolerate empty values):
+  AssertEqual '', ale#c#FlagsFromCompileCommands(bufnr(''), '')
+
+Execute(ParseCompileCommandsFlags should tolerate empty values):
+  AssertEqual '', ale#c#ParseCompileCommandsFlags(bufnr(''), '', [])
+
+Execute(ParseCompileCommandsFlags should parse some basic flags):
+  noautocmd execute 'file! ' . fnameescape('/foo/bar/xmms2-mpris/src/xmms2-mpris.c')
+
+  AssertEqual
+  \ '-I/usr/include/xmms2',
+  \ ale#c#ParseCompileCommandsFlags(bufnr(''), '/foo/bar/xmms2-mpris', [
+  \   {
+  \     'directory': '/foo/bar/xmms2-mpris',
+  \     'command': '/usr/bin/cc  -I/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'
+  \   },
+  \ ])
diff --git a/test/test_c_import_paths.vader b/test/test_c_import_paths.vader
index 0490dec6..70b25070 100644
--- a/test/test_c_import_paths.vader
+++ b/test/test_c_import_paths.vader
@@ -2,6 +2,7 @@ Before:
   " Make sure the c.vim file is loaded first.
   call ale#c#FindProjectRoot(bufnr(''))
 
+  Save g:ale_c_parse_makefile
   Save g:ale_c_gcc_options
   Save g:ale_c_clang_options
   Save g:ale_cpp_gcc_options
@@ -19,6 +20,7 @@ Before:
 
   call ale#test#SetDirectory('/testplugin/test')
 
+  let g:ale_c_parse_makefile = 0
   let g:ale_c_gcc_options = ''
   let g:ale_c_clang_options = ''
   let g:ale_cpp_gcc_options = ''
diff --git a/test/test_c_parse_makefile.vader b/test/test_c_parse_makefile.vader
deleted file mode 100644
index 7c2fc21e..00000000
--- a/test/test_c_parse_makefile.vader
+++ /dev/null
@@ -1,184 +0,0 @@
-Before:
-  Save g:ale_c_parse_makefile
-  Save g:ale_c_gcc_options
-  Save g:ale_c_clang_options
-  Save g:ale_cpp_gcc_options
-  Save g:ale_cpp_clang_options
-
-  call ale#test#SetDirectory('/testplugin/test')
-
-  let g:ale_c_parse_makefile=1
-  let g:ale_c_gcc_options = ''
-  let g:ale_c_clang_options = ''
-  let g:ale_cpp_gcc_options = ''
-  let g:ale_cpp_clang_options = ''
-
-After:
-  Restore
-
-  call ale#test#RestoreDirectory()
-  call ale#linter#Reset()
-
-Execute(The CFlags parser should be able to parse include directives):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   [ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir'))]
-  \ , ale#c#ParseCFlags(bufnr(''), 'gcc -Isubdir -c file.c')
-
-Execute(The CFlags parser should be able to parse macro directives):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   [ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    '-DTEST=1']
-  \ , ale#c#ParseCFlags(bufnr(''), 'gcc -Isubdir -DTEST=1 -c file.c')
-
-Execute(The CFlags parser should be able to parse macro directives with spaces):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   [ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    '-DTEST=$(( 2 * 4 ))']
-  \ , ale#c#ParseCFlags(bufnr(''), 'gcc -Isubdir -DTEST=$(( 2 * 4 )) -c file.c')
-
-Execute(The CFlags parser should be able to parse shell directives with spaces):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   [ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlags(bufnr(''), 'gcc -Isubdir -DTEST=`date +%s` -c file.c')
-
-Execute(The CFlagsToList parser should be able to parse multiple cflags):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   [ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlagsToList(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \                           split('gcc -Isubdir -DTEST=`date +%s` -c file.c', '-'))
-
-Execute(The CFlagsToList parser should be able to parse multiple cflags #2):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   [ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlagsToList(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \                           split('gcc -Isubdir  ' .
-  \                                 '-I'. ale#path#Simplify('kernel/include') .
-  \                                 ' -DTEST=`date +%s` -c file.c', '-'))
-
-Execute(The CFlagsToList parser should be able to parse multiple cflags #3):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   ['-Dgoal=9',
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlagsToList(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \                           split('gcc -Dgoal=9 -Isubdir ' .
-  \                                 '-I'. ale#path#Simplify('kernel/include') .
-  \                                 ' -DTEST=`date +%s` -c file.c', '-'))
-
-Execute(The CFlagsToList parser should be able to parse multiple cflags #4):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   ['-Dgoal=9',
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlagsToList(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \                           split('gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir ' .
-  \                                 '-I'. ale#path#Simplify('kernel/include') .
-  \                                 ' -DTEST=`date +%s` -c file.c', '-'))
-
-Execute(The CFlagsToList parser should be able to parse multiple cflags #5):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   ['-Dgoal=9',
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlagsToList(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \                           split('gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir ' .
-  \                                 '-I"dir with spaces"' . ' -I'. ale#path#Simplify('kernel/include') .
-  \                                 ' -DTEST=`date +%s` -c file.c', '-'))
-
-Execute(The CFlagsToList parser should be able to parse multiple cflags #6):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   ['-Dgoal=9',
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlagsToList(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \                           split('gcc -Dgoal=9 -Tlinkerfile.ld blabla -Isubdir ' .
-  \                                 '-I''dir with spaces''' . ' -I'. ale#path#Simplify('kernel/include') .
-  \                                 ' -DTEST=`date +%s` -c file.c', '-'))
-
-Execute(The CFlagsToList parser should be able to parse multiple cflags #7):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   ['-Dgoal=9',
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlagsToList(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \                           split('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', '-'))
-
-Execute(The CFlagsToList parser should be able to parse multiple cflags #8):
-  runtime! ale_linters/c/gcc.vim
-
-  call ale#test#SetFilename('test_c_projects/makefile_project/subdir/file.c')
-
-  AssertEqual
-  \   ['-Dgoal=9',
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/subdir')),
-  \    '-Dmacro-with-dash',
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir with spaces')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/dir-with-dash')),
-  \    ale#Escape('-I' . ale#path#Simplify(g:dir. '/test_c_projects/makefile_project/kernel/include')),
-  \    '-DTEST=`date +%s`']
-  \ , ale#c#ParseCFlagsToList(ale#path#Simplify(g:dir. '/test_c_projects/makefile_project'),
-  \                           split('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', '-'))
diff --git a/test/test_path_dirname.vader b/test/test_path_dirname.vader
new file mode 100644
index 00000000..79b78d29
--- /dev/null
+++ b/test/test_path_dirname.vader
@@ -0,0 +1,8 @@
+Execute(ale#path#Dirname should return empty strings should be returned for empty values):
+  AssertEqual '', ale#path#Dirname('')
+  AssertEqual '', ale#path#Dirname(0)
+  AssertEqual '', ale#path#Dirname(v:null)
+
+Execute(ale#path#Dirname should return the dirname of paths):
+  AssertEqual '/foo', ale#path#Dirname('/foo/bar')
+  AssertEqual '/foo', ale#path#Dirname('/foo/bar/')