nvim completion is working fine without this

vim/ftplugin/rust.vim

@@ -2,4 +2,6 @@ nmap <F5> :Cargo run<CR>
 nmap <F7> :Cargo check<CR>
 nmap <F8> :Cargo test<CR>
 
-nmap <C-]> :ALEGoToDefinition<CR>
+if !has('nvim')
+  nmap <C-]> :ALEGoToDefinition<CR>
+endif