From 05319a0ee40b85f414c37beefe029b78409f716e Mon Sep 17 00:00:00 2001
From: polusV <12313034@mail.sustech.edu.cn>
Date: Sat, 18 Apr 2026 11:11:48 +0800
Subject: [PATCH 1/2] Fix negative bool flag default=True with flag_value=False

---
 src/click/core.py     |  6 +++++-
 tests/test_options.py | 17 ++++++++++++++++-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/click/core.py b/src/click/core.py
index f0a624be3..844d48b8b 100644
--- a/src/click/core.py
+++ b/src/click/core.py
@@ -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:
+        if (
+            value is True
+            and self.is_flag
+            and not (self.is_bool_flag and self.flag_value is False)
+        ):
             value = self.flag_value
         elif call and callable(value):
             value = value()
diff --git a/tests/test_options.py b/tests/test_options.py
index e335f3c1a..78ccb318c 100644
--- a/tests/test_options.py
+++ b/tests/test_options.py
@@ -1435,7 +1435,7 @@ 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),
@@ -1480,6 +1480,21 @@ def cmd(foo):
     assert result.output == repr(expected)
 
 
+def test_negative_boolean_flag_value_preserves_true_default(runner):
+    @click.command()
+    @click.option(
+        "--without-xyz", "enable_xyz", is_flag=True, flag_value=False, default=True
+    )
+    def cmd(enable_xyz):
+        click.echo(repr(enable_xyz), nl=False)
+
+    result = runner.invoke(cmd, [])
+    assert result.output == "True"
+
+    result = runner.invoke(cmd, ["--without-xyz"])
+    assert result.output == "False"
+
+
 @pytest.mark.parametrize(
     ("args", "opts"),
     [

From 902c27625f21a0d584edaebc16f80e95fcee86a9 Mon Sep 17 00:00:00 2001
From: polusV <12313034@mail.sustech.edu.cn>
Date: Sat, 18 Apr 2026 11:19:35 +0800
Subject: [PATCH 2/2] Update prompt expectations for bool flag default=True and
 flag_value=False

---
 tests/test_termui.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/test_termui.py b/tests/test_termui.py
index 8220431bb..7f0881779 100644
--- a/tests/test_termui.py
+++ b/tests/test_termui.py
@@ -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),