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Fix negative flag (flag_value=False) ignoring default=True #3308

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Fix negative flag (flag_value=False) ignoring default=True #3308

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db955d8
Fix negative flag with default=True returning wrong value
vigneshakaviki Apr 5, 2026
54eac52
Fix ruff line-length and formatting issues in tests
vigneshakaviki Apr 5, 2026
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6 changes: 5 additions & 1 deletion src/click/core.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2897,7 +2897,11 @@ def get_default(
# (instead of eagerly in __init__) prevents callable flag_values
# (like classes) from being instantiated by the callable check below.
# https://github.com/pallets/click/issues/3121
if value is True and self.is_flag:
# Skip the conversion when flag_value is explicitly False (a negative flag).
# For negative flags, default=True is the literal default value — not a signal
# to activate the flag. Converting it to False would silently override the
# user's explicit default. https://github.com/pallets/click/issues/3111
if value is True and self.is_flag and self.flag_value is not False:
value = self.flag_value
elif call and callable(value):
value = value()
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29 changes: 27 additions & 2 deletions tests/test_options.py
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Expand Up @@ -1435,13 +1435,13 @@ def test_type_from_flag_value():
# Not passing --foo returns the default value as-is, in its Python type, then
# converted by the option type.
({"type": bool, "default": True, "flag_value": True}, [], True),
({"type": bool, "default": True, "flag_value": False}, [], False),
({"type": bool, "default": True, "flag_value": False}, [], True),
({"type": bool, "default": False, "flag_value": True}, [], False),
({"type": bool, "default": False, "flag_value": False}, [], False),
({"type": bool, "default": None, "flag_value": True}, [], None),
({"type": bool, "default": None, "flag_value": False}, [], None),
({"type": str, "default": True, "flag_value": True}, [], "True"),
({"type": str, "default": True, "flag_value": False}, [], "False"),
({"type": str, "default": True, "flag_value": False}, [], "True"),
({"type": str, "default": False, "flag_value": True}, [], "False"),
({"type": str, "default": False, "flag_value": False}, [], "False"),
({"type": str, "default": "foo", "flag_value": True}, [], "foo"),
Expand Down Expand Up @@ -1480,6 +1480,31 @@ def cmd(foo):
assert result.output == repr(expected)


def test_negative_flag_with_true_default(runner):
"""A negative flag (flag_value=False, default=True) should return True when not
passed and False when passed. Regression test for https://github.com/pallets/click/issues/3111."""

@click.command()
@click.option(
"--without-xyz",
"enable_xyz",
flag_value=False,
default=True,
)
def cmd(enable_xyz):
click.echo(repr(enable_xyz), nl=False)

result = runner.invoke(cmd, [])
assert result.output == "True", (
"default=True should be returned when flag is not passed"
)

result = runner.invoke(cmd, ["--without-xyz"])
assert result.output == "False", (
"flag_value=False should be returned when flag is passed"
)


@pytest.mark.parametrize(
("args", "opts"),
[
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6 changes: 3 additions & 3 deletions tests/test_termui.py
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Expand Up @@ -604,9 +604,9 @@ def cmd(arg1):
({"prompt": True, "default": True, "flag_value": True}, [], "[Y/n]", "", True),
({"prompt": True, "default": True, "flag_value": True}, [], "[Y/n]", "y", True),
({"prompt": True, "default": True, "flag_value": True}, [], "[Y/n]", "n", False),
({"prompt": True, "default": True, "flag_value": False}, [], "[y/N]", "", False),
({"prompt": True, "default": True, "flag_value": False}, [], "[y/N]", "y", True),
({"prompt": True, "default": True, "flag_value": False}, [], "[y/N]", "n", False),
({"prompt": True, "default": True, "flag_value": False}, [], "[Y/n]", "", True),
({"prompt": True, "default": True, "flag_value": False}, [], "[Y/n]", "y", True),
({"prompt": True, "default": True, "flag_value": False}, [], "[Y/n]", "n", False),
# default=False
({"prompt": True, "default": False, "flag_value": True}, [], "[y/N]", "", False),
({"prompt": True, "default": False, "flag_value": True}, [], "[y/N]", "y", True),
Expand Down