Fix bashautocompletion of arguments on chained commands

CHANGES

@@ -8,7 +8,7 @@ Version 7.0
 
 (upcoming release with new features, release date to be decided)
 - Added support for dynamic bash completion from a user-supplied callback.
-  See #755
+  See #755.
 - Added support for bash completion of type=click.Choice for Options and
   Arguments. See #535.
 - The user is now presented with the available choices if prompt=True and
@@ -22,6 +22,8 @@ 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 
+  chained commands. See #774.
 
 Version 6.8
 -----------

click/_bashcomplete.py

@@ -42,14 +42,18 @@ def resolve_ctx(cli, prog_name, args):
     :return: the final context/command parsed
     """
     ctx = cli.make_context(prog_name, args, resilient_parsing=True)
-    while ctx.protected_args + ctx.args and isinstance(ctx.command, MultiCommand):
-        a = ctx.protected_args + ctx.args
-        cmd = ctx.command.get_command(ctx, a[0])
+    args_remaining = ctx.protected_args + ctx.args
+    while ctx is not None and args_remaining:
+      if isinstance(ctx.command, MultiCommand):
+        cmd = ctx.command.get_command(ctx, args_remaining[0])
         if cmd is None:
             return None
-        ctx = cmd.make_context(a[0], a[1:], parent=ctx, resilient_parsing=True)
-    return ctx
+        ctx = cmd.make_context(args_remaining[0], args_remaining[1:], parent=ctx, resilient_parsing=True)
+        args_remaining = ctx.protected_args + ctx.args
+      else:
+        ctx = ctx.parent
 
+    return ctx
 
 def start_of_option(param_str):
     """
@@ -164,6 +168,11 @@ def get_choices(cli, prog_name, args, incomplete):
         # 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)
+
     for item in choices:
         if item.startswith(incomplete):
             yield item

tests/test_bashcomplete.py

@@ -112,6 +112,32 @@ def csub(csub_opt, color):
     assert list(get_choices(cli, 'lol', ['asub', 'bsub', 'csub'], 'b')) == ['blue']
 
 
+def test_chaining():
+    @click.group('cli', chain=True)
+    @click.option('--cli-opt')
+    def cli(cli_opt):
+        pass
+
+    @cli.command('asub')
+    @click.option('--asub-opt')
+    def asub(asub_opt):
+        pass
+
+    @cli.command('bsub')
+    @click.option('--bsub-opt')
+    @click.argument('arg', type=click.Choice(['arg1', 'arg2']))
+    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', ['asub', '--asub-opt', '5', 'bsub'], '-')) == ['--bsub-opt']
+    assert list(get_choices(cli, 'lol', ['asub', 'bsub'], '-')) == ['--bsub-opt']
+
+
 def test_argument_choice():
     @click.command()
     @click.argument('arg1', required=False, type=click.Choice(['arg11', 'arg12']))