Add delay for parallel destroy without force, restructure state checking

This commit adds better messaging to the user if the parallel flag is
used without the force flag. It also makes the state checking based on
the delta between the initial and final states of the guests due to the
fact that there is no guarantee what the "destroyed" state id will be
between providers.

plugins/commands/destroy/command.rb

@@ -20,7 +20,7 @@ module VagrantPlugins
           end
 
           o.on("--[no-]parallel",
-               "Enable or disable parallelism if provider supports it") do |p|
+               "Enable or disable parallelism if provider supports it (automatically enables force)") do |p|
             options[:parallel] = p
           end
         end
@@ -29,13 +29,22 @@ module VagrantPlugins
         argv = parse_options(opts)
         return if !argv
 
-        @logger.debug("'Destroy' each target VM...")
-
-        if options[:parallel]
+        if options[:parallel] && !options[:force]
+          @env.ui.warn(I18n.t("vagrant.commands.destroy.warning"))
+          sleep(5)
           options[:force] = true
         end
 
+        @logger.debug("'Destroy' each target VM...")
+
         machines = []
+        init_states = {}
+        declined = 0
+
+        # gather states to be checked after destroy
+        with_target_vms(argv, reverse: true) do |vm|
+          init_states[vm.name] = vm.state.id
+        end
 
         @env.batch(options[:parallel]) do |batch|
           with_target_vms(argv, reverse: true) do |vm|
@@ -44,17 +53,20 @@ module VagrantPlugins
           end
         end
 
-        states = machines.map { |m| m.state.id }
-        if states.uniq.length == 1 && states.first == :not_created
-          # Nothing was declined
-          return 0
-        elsif states.uniq.length == 1 && states.first != :not_created
-          # Everything was declined
-          return 1
-        else
-          # Some was declined
-          return 2
+        machines.each do |m|
+          if m.state.id == init_states[m.name]
+            declined += 1
+          end
         end
+
+        # Nothing was declined
+        return 0 if declined == 0
+
+        # Everything was declined, state was not changed
+        return 1 if declined == machines.length
+
+        # Some was declined
+        return 2
       end
     end
   end

templates/locales/en.yml

@@ -1697,6 +1697,9 @@ en:
         will_not_destroy: |-
           The VM '%{name}' will not be destroyed, since the confirmation
           was declined.
+        warning: |-
+          Destroying guests with `--parallel` automatically enables `--force`.
+          Press ctrl-c to cancel.
       init:
         success: |-
           A `Vagrantfile` has been placed in this directory. You are now