dfmt support (#2662)

* Add support for `dfmt`

autoload/ale/fix/registry.vim

@@ -27,6 +27,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['python'],
 \       'description': 'Fix PEP8 issues with black.',
 \   },
+\   'dfmt': {
+\       'function': 'ale#fixers#dfmt#Fix',
+\       'suggested_filetypes': ['d'],
+\       'description': 'Fix D files with dfmt.',
+\   },
 \   'fecs': {
 \       'function': 'ale#fixers#fecs#Fix',
 \       'suggested_filetypes': ['javascript', 'css', 'html'],

autoload/ale/fixers/dfmt.vim

@@ -0,0 +1,18 @@
+" Author: theoldmoon0602
+" Description: Integration of dfmt with ALE.
+
+call ale#Set('d_dfmt_executable', 'dfmt')
+call ale#Set('d_dfmt_options', '')
+
+function! ale#fixers#dfmt#Fix(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'd_dfmt_executable')
+    let l:options = ale#Var(a:buffer, 'd_dfmt_options')
+
+    return {
+    \   'command': ale#Escape(l:executable)
+    \       . ' -i'
+    \       . (empty(l:options) ? '' : ' ' . l:options)
+    \       . ' %t',
+    \   'read_temporary_file': 1,
+    \}
+endfunction