Fix overzealous completion when required options/arguments are being completed

CHANGES

@@ -23,9 +23,12 @@ Version 7.0
 - ``launch`` now works properly under Cygwin. See #650.
 - `CliRunner.invoke` now may receive `args` as a string representing
   a Unix shell command. See #664.
-- Fix bug that caused bashcompletion to give inproper completions on 
+- Fix bug that caused bashcompletion to give improper completions on 
   chained commands. See #774.
 - 't' and 'f' are now converted to True and False. 
+- Fix bug that caused bashcompletion to give improper completions on
+  chained commands when a required option/argument was being completed.
+  See #790.
 
 Version 6.8
 -----------

click/_bashcomplete.py

@@ -56,6 +56,7 @@ def resolve_ctx(cli, prog_name, args):
 
     return ctx
 
+
 def start_of_option(param_str):
     """
     :param param_str: param_str to check
@@ -72,6 +73,8 @@ def is_incomplete_option(all_args, cmd_param):
     corresponds to this cmd_param. In other words whether this cmd_param option can still accept
     values
     """
+    if not isinstance(cmd_param, Option):
+        return False
     if cmd_param.is_flag:
         return False
     last_option = None
@@ -91,6 +94,8 @@ def is_incomplete_argument(current_params, cmd_param):
     :return: whether or not the last argument is incomplete and corresponds to this cmd_param. In
     other words whether or not the this cmd_param argument can still accept values
     """
+    if not isinstance(cmd_param, Argument):
+        return False
     current_param_values = current_params[cmd_param.name]
     if current_param_values is None:
         return True
@@ -118,6 +123,7 @@ def get_user_autocompletions(ctx, args, incomplete, cmd_param):
     else:
         return []
 
+
 def get_choices(cli, prog_name, args, incomplete):
     """
     :param cli: command definition
@@ -144,35 +150,38 @@ def get_choices(cli, prog_name, args, incomplete):
     choices = []
     found_param = False
     if start_of_option(incomplete):
-        # completions for options
+        # completions for partial options
         for param in ctx.command.params:
             if isinstance(param, Option):
                 choices.extend([param_opt for param_opt in param.opts + param.secondary_opts
                                 if param_opt not in all_args or param.multiple])
-        found_param = True
-    if not found_param:
-        # completion for option values by choices
-        for cmd_param in ctx.command.params:
-            if isinstance(cmd_param, Option) and is_incomplete_option(all_args, cmd_param):
-                choices.extend(get_user_autocompletions(ctx, all_args, incomplete, cmd_param))
-                found_param = True
-                break
-    if not found_param:
-        # completion for argument values by choices
-        for cmd_param in ctx.command.params:
-            if isinstance(cmd_param, Argument) and is_incomplete_argument(ctx.params, cmd_param):
-                choices.extend(get_user_autocompletions(ctx, all_args, incomplete, cmd_param))
+    else:
+        # completion for option values from user supplied values
+        for param in ctx.command.params:
+            if is_incomplete_option(all_args, param):
+                choices.extend(get_user_autocompletions(ctx, all_args, incomplete, param))
                 found_param = True
                 break
-
-    if not found_param and isinstance(ctx.command, MultiCommand):
-        # completion for any subcommands
-        choices.extend(ctx.command.list_commands(ctx))
-
-    if not start_of_option(incomplete) and ctx.parent is not None and isinstance(ctx.parent.command, MultiCommand) and ctx.parent.command.chain:
-        # completion for chained commands
-        remaining_comands = set(ctx.parent.command.list_commands(ctx.parent))-set(ctx.parent.protected_args)
-        choices.extend(remaining_comands)
+        # completion for argument values from user supplied values
+        if not found_param:
+            for param in ctx.command.params:
+                if is_incomplete_argument(ctx.params, param):
+                    choices.extend(get_user_autocompletions(ctx, all_args, incomplete, param))
+                    # Stop looking for other completions only if this argument is required
+                    found_param = param.required
+                    break
+
+        if not found_param and isinstance(ctx.command, MultiCommand):
+            # completion for any subcommands
+            choices.extend(ctx.command.list_commands(ctx))
+
+        if not found_param:
+            # Walk up the context list and add any other completion possibilities from chained commands
+            while ctx.parent is not None:
+                ctx = ctx.parent
+                if isinstance(ctx.command, MultiCommand) and ctx.command.chain:
+                    remaining_commands = set(ctx.command.list_commands(ctx))-set(ctx.protected_args)
+                    choices.extend(remaining_commands)
 
     for item in choices:
         if item.startswith(incomplete):

tests/test_bashcomplete.py

@@ -125,15 +125,16 @@ def asub(asub_opt):
 
     @cli.command('bsub')
     @click.option('--bsub-opt')
-    @click.argument('arg', type=click.Choice(['arg1', 'arg2']))
+    @click.argument('arg', type=click.Choice(['arg1', 'arg2']), required=True)
     def bsub(bsub_opt, arg):
         pass
 
     assert list(get_choices(cli, 'lol', [], '-')) == ['--cli-opt']
     assert list(get_choices(cli, 'lol', [], '')) == ['asub', 'bsub']
     assert list(get_choices(cli, 'lol', ['asub'], '-')) == ['--asub-opt']
     assert list(get_choices(cli, 'lol', ['asub'], '')) == ['bsub']
-    assert list(get_choices(cli, 'lol', ['bsub'], '')) == ['arg1', 'arg2', 'asub']
+    assert list(get_choices(cli, 'lol', ['bsub'], '')) == ['arg1', 'arg2']
+    assert list(get_choices(cli, 'lol', ['asub', '--asub-opt'], '')) == []
     assert list(get_choices(cli, 'lol', ['asub', '--asub-opt', '5', 'bsub'], '-')) == ['--bsub-opt']
     assert list(get_choices(cli, 'lol', ['asub', 'bsub'], '-')) == ['--bsub-opt']
 
@@ -255,10 +256,10 @@ def sub(sub_opt):
     def bsub(bsub_opt):
         pass
 
-    assert list(get_choices(cli, 'lol', ['sub'], '')) == ['subarg1', 'subarg2']
+    assert list(get_choices(cli, 'lol', ['sub'], '')) == ['subarg1', 'subarg2', 'bsub']
     assert list(get_choices(cli, 'lol', ['sub', '--sub-opt'], '')) == ['subopt1', 'subopt2']
     assert list(get_choices(cli, 'lol', ['sub', '--sub-opt', 'subopt1'], '')) == \
-        ['subarg1', 'subarg2']
+        ['subarg1', 'subarg2', 'bsub']
     assert list(get_choices(cli, 'lol',
         ['sub', '--sub-opt', 'subopt1', 'subarg1', 'bsub'], '-')) == ['--bsub-opt']
     assert list(get_choices(cli, 'lol',