Add support for lua-language-server

autoload/ale/lua.vim

@@ -0,0 +1,28 @@
+" Author: w0rp <dev@w0rp.com>
+" Description: Functions for integrating with Lua linters.
+
+" Find project root for a Lua language server.
+function! ale#lua#FindProjectRoot(buffer) abort
+    let l:possible_project_roots = [
+    \   '.git',
+    \   bufname(a:buffer),
+    \]
+
+    for l:possible_root in l:possible_project_roots
+        let l:project_root = ale#path#FindNearestFile(a:buffer, l:possible_root)
+
+        if empty(l:project_root)
+            let l:project_root = ale#path#FindNearestDirectory(a:buffer, l:possible_root)
+        endif
+
+        if !empty(l:project_root)
+            " dir:p expands to /full/path/to/dir/ whereas
+            " file:p expands to /full/path/to/file (no trailing slash)
+            " Appending '/' ensures that :h:h removes the path's last segment
+            " regardless of whether it is a directory or not.
+            return fnamemodify(l:project_root . '/', ':p:h:h')
+        endif
+    endfor
+
+    return ''
+endfunction