Rewrite to make shell completion pull option prefixes from the parser

src/click/core.py

@@ -292,6 +292,8 @@ def __init__(
         #: must be never propagated to another arguments.  This is used
         #: to implement nested parsing.
         self.protected_args: t.List[str] = []
+        #: the collected prefixes of the command's options.
+        self.opt_prefixes: t.Set[str] = set(parent.opt_prefixes) if parent else set()
 
         if obj is None and parent is not None:
             obj = parent.obj
@@ -1385,6 +1387,7 @@ def parse_args(self, ctx: Context, args: t.List[str]) -> t.List[str]:
             )
 
         ctx.args = args
+        ctx.opt_prefixes.update(parser.opt_prefixes)
         return args
 
     def invoke(self, ctx: Context) -> t.Any:

src/click/parser.py

@@ -278,14 +278,15 @@ def __init__(self, ctx: t.Optional["Context"] = None) -> None:
         #: second mode where it will ignore it and continue processing
         #: after shifting all the unknown options into the resulting args.
         self.ignore_unknown_options = False
+        #: The collected prefixes of the options added to the parser.
+        self.opt_prefixes = {"-", "--"}
 
         if ctx is not None:
             self.allow_interspersed_args = ctx.allow_interspersed_args
             self.ignore_unknown_options = ctx.ignore_unknown_options
 
         self._short_opt: t.Dict[str, Option] = {}
         self._long_opt: t.Dict[str, Option] = {}
-        self._opt_prefixes = {"-", "--"}
         self._args: t.List[Argument] = []
 
     def add_option(
@@ -307,7 +308,7 @@ def add_option(
         """
         opts = [normalize_opt(opt, self.ctx) for opt in opts]
         option = Option(obj, opts, dest, action=action, nargs=nargs, const=const)
-        self._opt_prefixes.update(option.prefixes)
+        self.opt_prefixes.update(option.prefixes)
         for opt in option._short_opts:
             self._short_opt[opt] = option
         for opt in option._long_opts:
@@ -360,7 +361,7 @@ def _process_args_for_options(self, state: ParsingState) -> None:
             # prefixes are valid.
             if arg == "--":
                 return
-            elif arg[:1] in self._opt_prefixes and arglen > 1:
+            elif arg[:1] in self.opt_prefixes and arglen > 1:
                 self._process_opts(arg, state)
             elif self.allow_interspersed_args:
                 state.largs.append(arg)
@@ -482,7 +483,7 @@ def _get_value_from_state(
             if (
                 option.obj._flag_needs_value
                 and isinstance(next_rarg, str)
-                and next_rarg[:1] in self._opt_prefixes
+                and next_rarg[:1] in self.opt_prefixes
                 and len(next_rarg) > 1
             ):
                 # The next arg looks like the start of an option, don't
@@ -519,7 +520,7 @@ def _process_opts(self, arg: str, state: ParsingState) -> None:
             # (applies to "--foo" for instance), we do not dispatch to the
             # short option code and will instead raise the no option
             # error.
-            if arg[:2] not in self._opt_prefixes:
+            if arg[:2] not in self.opt_prefixes:
                 self._match_short_opt(arg, state)
                 return
 

src/click/shell_completion.py

@@ -448,17 +448,16 @@ def _is_incomplete_argument(ctx: Context, param: Parameter) -> bool:
     )
 
 
-def _start_of_option(value: str) -> bool:
+def _start_of_option(ctx: Context, value: str) -> bool:
     """Check if the value looks like the start of an option."""
     if not value:
         return False
 
     c = value[0]
-    # Allow "/" since that starts a path.
-    return not c.isalnum() and c != "/"
+    return c in ctx.opt_prefixes
 
 
-def _is_incomplete_option(args: t.List[str], param: Parameter) -> bool:
+def _is_incomplete_option(ctx: Context, args: t.List[str], param: Parameter) -> bool:
     """Determine if the given parameter is an option that needs a value.
 
     :param args: List of complete args before the incomplete value.
@@ -476,7 +475,7 @@ def _is_incomplete_option(args: t.List[str], param: Parameter) -> bool:
         if index + 1 > param.nargs:
             break
 
-        if _start_of_option(arg):
+        if _start_of_option(ctx, arg):
             last_option = arg
 
     return last_option is not None and last_option in param.opts
@@ -551,25 +550,25 @@ def _resolve_incomplete(
     # split and discard the "=" to make completion easier.
     if incomplete == "=":
         incomplete = ""
-    elif "=" in incomplete and _start_of_option(incomplete):
+    elif "=" in incomplete and _start_of_option(ctx, incomplete):
         name, _, incomplete = incomplete.partition("=")
         args.append(name)
 
+    # The "--" marker tells Click to stop treating values as options
+    # even if they start with the option character. If it hasn't been
+    # given and the incomplete arg looks like an option, the current
+    # command will provide option name completions.
+    if "--" not in args and _start_of_option(ctx, incomplete):
+        return ctx.command, incomplete
+
     params = ctx.command.get_params(ctx)
 
     # If the last complete arg is an option name with an incomplete
     # value, the option will provide value completions.
     for param in params:
-        if _is_incomplete_option(args, param):
+        if _is_incomplete_option(ctx, args, param):
             return param, incomplete
 
-    # The "--" marker tells Click to stop treating values as options
-    # even if they start with the option character. If it hasn't been
-    # given and the incomplete arg looks like an option, the current
-    # command will provide option name completions.
-    if "--" not in args and _start_of_option(incomplete):
-        return ctx.command, incomplete
-
     # It's not an option name or value. The first argument without a
     # parsed value will provide value completions.
     for param in params:

tests/test_commands.py

@@ -352,3 +352,62 @@ def deprecated_cmd():
 
     result = runner.invoke(deprecated_cmd)
     assert "DeprecationWarning:" in result.output
+
+
+def test_command_parse_args_collects_option_prefixes():
+    @click.command()
+    @click.option("+p", is_flag=True)
+    @click.option("!e", is_flag=True)
+    def test(p, e):
+        pass
+
+    ctx = click.Context(test)
+    test.parse_args(ctx, [])
+
+    assert ctx.opt_prefixes == {"-", "--", "+", "!"}
+
+
+def test_group_parse_args_collects_base_option_prefixes():
+    @click.group()
+    @click.option("~t", is_flag=True)
+    def group(t):
+        pass
+
+    @group.command()
+    @click.option("+p", is_flag=True)
+    def command1(p):
+        pass
+
+    @group.command()
+    @click.option("!e", is_flag=True)
+    def command2(e):
+        pass
+
+    ctx = click.Context(group)
+    group.parse_args(ctx, ["command1", "+p"])
+
+    assert ctx.opt_prefixes == {"-", "--", "~"}
+
+
+def test_group_invoke_collects_used_option_prefixes(runner):
+    opt_prefixes = set()
+
+    @click.group()
+    @click.option("~t", is_flag=True)
+    def group(t):
+        pass
+
+    @group.command()
+    @click.option("+p", is_flag=True)
+    @click.pass_context
+    def command1(ctx, p):
+        nonlocal opt_prefixes
+        opt_prefixes = ctx.opt_prefixes
+
+    @group.command()
+    @click.option("!e", is_flag=True)
+    def command2(e):
+        pass
+
+    runner.invoke(group, ["command1"])
+    assert opt_prefixes == {"-", "--", "~", "+"}

tests/test_context.py

@@ -365,3 +365,11 @@ def cli(ctx, option):
 
     rv = runner.invoke(cli, standalone_mode=False, **invoke_args)
     assert rv.return_value == expect
+
+
+def test_propagate_opt_prefixes():
+    parent = click.Context(click.Command("test"))
+    parent.opt_prefixes = {"-", "--", "!"}
+    ctx = click.Context(click.Command("test2"), parent=parent)
+
+    assert ctx.opt_prefixes == {"-", "--", "!"}

tests/test_parser.py

@@ -1,5 +1,7 @@
 import pytest
 
+import click
+from click.parser import OptionParser
 from click.parser import split_arg_string
 
 
@@ -15,3 +17,16 @@
 )
 def test_split_arg_string(value, expect):
     assert split_arg_string(value) == expect
+
+
+def test_parser_default_prefixes():
+    parser = OptionParser()
+    assert parser.opt_prefixes == {"-", "--"}
+
+
+def test_parser_collects_prefixes():
+    ctx = click.Context(click.Command("test"))
+    parser = OptionParser(ctx)
+    click.Option("+p", is_flag=True).add_to_parser(parser, ctx)
+    click.Option("!e", is_flag=True).add_to_parser(parser, ctx)
+    assert parser.opt_prefixes == {"-", "--", "+", "!"}

tests/test_shell_completion.py

@@ -117,12 +117,38 @@ def test_choice_special_characters():
     assert _get_words(cli, ["-c"], "!2") == ["!2"]
 
 
+def test_choice_conflicting_prefix():
+    cli = Command(
+        "cli",
+        params=[
+            Option(["-c"], type=Choice(["!1", "!2", "+3"])),
+            Option(["+p"], is_flag=True),
+        ],
+    )
+    assert _get_words(cli, ["-c"], "") == ["!1", "!2", "+3"]
+    assert _get_words(cli, ["-c"], "+") == ["+p"]
+
+
 def test_option_count():
     cli = Command("cli", params=[Option(["-c"], count=True)])
     assert _get_words(cli, ["-c"], "") == []
     assert _get_words(cli, ["-c"], "-") == ["--help"]
 
 
+def test_option_optional():
+    cli = Command(
+        "cli",
+        add_help_option=False,
+        params=[
+            Option(["--name"], is_flag=False, flag_value="value"),
+            Option(["--flag"], is_flag=True),
+        ],
+    )
+    assert _get_words(cli, ["--name"], "") == []
+    assert _get_words(cli, ["--name"], "-") == ["--flag"]
+    assert _get_words(cli, ["--name", "--flag"], "-") == []
+
+
 @pytest.mark.parametrize(
     ("type", "expect"),
     [(File(), "file"), (Path(), "file"), (Path(file_okay=False), "dir")],