From 79c51223d9e92bb2efed1b248056b730a71b12e7 Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <61934744+phofl@users.noreply.github.com>
Date: Tue, 17 Aug 2021 08:26:16 +0200
Subject: [PATCH] Backport PR #43041: Fix len one list dataframe constructor
 bug for datetime

---
 doc/source/whatsnew/v1.3.3.rst          |  1 +
 pandas/core/construction.py             |  1 -
 pandas/tests/frame/test_constructors.py | 15 +++++++++++++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v1.3.3.rst b/doc/source/whatsnew/v1.3.3.rst
index b3cd6d00d4322..549d0dcb593fd 100644
--- a/doc/source/whatsnew/v1.3.3.rst
+++ b/doc/source/whatsnew/v1.3.3.rst
@@ -14,6 +14,7 @@ including other versions of pandas.
 
 Fixed regressions
 ~~~~~~~~~~~~~~~~~
+- Fixed regression in :class:`DataFrame` constructor failing to broadcast for defined :class:`Index` and len one list of :class:`Timestamp` (:issue:`42810`)
 - Performance regression in :meth:`core.window.ewm.ExponentialMovingWindow.mean` (:issue:`42333`)
 -
 -
diff --git a/pandas/core/construction.py b/pandas/core/construction.py
index 68d7f6c6f8a22..9d48bf612eb11 100644
--- a/pandas/core/construction.py
+++ b/pandas/core/construction.py
@@ -552,7 +552,6 @@ def sanitize_array(
             subarr = subarr.astype(dtype, copy=copy)
         elif copy:
             subarr = subarr.copy()
-        return subarr
 
     else:
         if isinstance(data, (set, frozenset)):
diff --git a/pandas/tests/frame/test_constructors.py b/pandas/tests/frame/test_constructors.py
index 1d286e379da86..94fba0cbb90d5 100644
--- a/pandas/tests/frame/test_constructors.py
+++ b/pandas/tests/frame/test_constructors.py
@@ -1286,6 +1286,21 @@ def test_constructor_unequal_length_nested_list_column(self):
         with pytest.raises(ValueError, match=msg):
             DataFrame([[1, 2, 3, 4], [4, 5, 6, 7]], columns=arrays)
 
+    @pytest.mark.parametrize(
+        "data",
+        [
+            [[Timestamp("2021-01-01")]],
+            [{"x": Timestamp("2021-01-01")}],
+            {"x": [Timestamp("2021-01-01")]},
+            {"x": Timestamp("2021-01-01")},
+        ],
+    )
+    def test_constructor_one_element_data_list(self, data):
+        # GH#42810
+        result = DataFrame(data, index=[0, 1, 2], columns=["x"])
+        expected = DataFrame({"x": [Timestamp("2021-01-01")] * 3})
+        tm.assert_frame_equal(result, expected)
+
     def test_constructor_sequence_like(self):
         # GH 3783
         # collections.Sequence like