Add gnatpp fixer for Ada

autoload/ale/fix/registry.vim

@@ -315,6 +315,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['python'],
 \       'description': 'Sort Python imports with reorder-python-imports.',
 \   },
+\   'gnatpp': {
+\       'function': 'ale#fixers#gnatpp#Fix',
+\       'suggested_filetypes': ['ada'],
+\       'description': 'Format Ada files with gnatpp.',
+\   },
 \}
 
 " Reset the function registry to the default entries.

autoload/ale/fixers/gnatpp.vim

@@ -0,0 +1,17 @@
+" Author: tim <tim@inept.tech>
+" Description: Fix files with gnatpp.
+
+call ale#Set('ada_gnatpp_executable', 'gnatpp')
+call ale#Set('ada_gnatpp_options', '')
+
+function! ale#fixers#gnatpp#Fix(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'ada_gnatpp_executable')
+    let l:options = ale#Var(a:buffer, 'ada_gnatpp_options')
+
+    return {
+    \   'command': ale#Escape(l:executable)
+    \       . (!empty(l:options) ? ' ' . l:options : '')
+    \       . ' %t',
+    \   'read_temporary_file': 1,
+    \}
+endfunction