From 54f22c218bee1703cefa6601f5091c063342f152 Mon Sep 17 00:00:00 2001
From: chuenchen309 <48723787+chuenchen309@users.noreply.github.com>
Date: Sun, 19 Jul 2026 12:07:49 +0800
Subject: [PATCH] Don't leak TypeError from Coerce when the type is a non-class
 callable

Coerce accepts any callable (`type: Union[type, Callable]`), and its
docstring promises that a ValueError/TypeError from the constructor marks
the value Invalid. But the failure handler called
`issubclass(self.type, Enum)`, which raises `TypeError: issubclass() arg 1
must be a class` when `self.type` is a function -- and that call is outside
the try, so it escaped as a raw TypeError instead of a CoerceInvalid.
So `Schema(Coerce(datetime.fromisoformat))('x')` or any
`Coerce(some_parse_func)` crashed on the invalid-input path rather than
producing MultipleInvalid, bypassing error paths and `humanize`.

Guard the Enum check with `isinstance(self.type, type)`; the class path
(including the Enum value listing) is unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: chuenchen309 <48723787+chuenchen309@users.noreply.github.com>
---
 voluptuous/tests/tests.py | 14 ++++++++++++++
 voluptuous/validators.py  |  7 ++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/voluptuous/tests/tests.py b/voluptuous/tests/tests.py
index 0608548..b3e6f17 100644
--- a/voluptuous/tests/tests.py
+++ b/voluptuous/tests/tests.py
@@ -1745,6 +1745,20 @@ def test_coerce_in_set_is_applied():
     assert Schema({int})({1, 2}) == {1, 2}
 
 
+def test_coerce_callable_marks_invalid_without_msg():
+    # Coerce accepts any callable (not just a class). When such a callable
+    # raises on bad input, the value must be marked Invalid, as the docstring
+    # promises -- the Enum-message branch used to call issubclass() on the
+    # callable and leak a raw TypeError. See the class twin Coerce(int), which
+    # already behaves this way.
+    def parse_int(v):
+        return int(v)
+
+    validate = Schema(Coerce(parse_int))
+    with raises(MultipleInvalid, 'expected parse_int'):
+        validate('foo')
+
+
 def test_lower_util_handles_various_inputs():
     assert Lower(3) == "3"
     assert Lower(u"3") == u"3"
diff --git a/voluptuous/validators.py b/voluptuous/validators.py
index a69bb8a..510ab34 100644
--- a/voluptuous/validators.py
+++ b/voluptuous/validators.py
@@ -145,7 +145,12 @@ def __call__(self, v):
             return self.type(v)
         except (ValueError, TypeError, InvalidOperation):
             msg = self.msg or ('expected %s' % self.type_name)
-            if not self.msg and Enum and issubclass(self.type, Enum):
+            if (
+                not self.msg
+                and Enum
+                and isinstance(self.type, type)
+                and issubclass(self.type, Enum)
+            ):
                 msg += " or one of %s" % str([e.value for e in self.type])[1:-1]
             raise CoerceInvalid(msg)