Normalize DateTime casts to UTC for :time and :time_usec (#4792)

#4775 moved :date, :naive_datetime and :naive_datetime_usec onto the UTC
instant when given a non-UTC %DateTime{}, but cast_time/1 has no %DateTime{}
clause, so it falls through to the map clauses and rebuilds a Time from the
wall-clock fields.

Author: youdie006

CHANGELOG.md

@@ -11,6 +11,7 @@
 
   * [Ecto.Query] Fix subqueries in interpolated join filters (this changes the representation of `JoinExpr.on` fields to a `BooleanExpr`)
   * [Ecto.Query] Fix selecting lists of fields and using `map/2` from subqueries
+  * [Ecto.Type] Normalize `DateTime` casts to UTC for `:time` and `:time_usec`
 
 ## v3.14.2 (2026-08-14)
 

lib/ecto/type.ex

@@ -1114,6 +1114,13 @@ defmodule Ecto.Type do
     end
   end
 
+  defp cast_time(%DateTime{} = datetime) do
+    case cast_utc_datetime(datetime) do
+      {:ok, datetime} -> {:ok, DateTime.to_time(datetime)}
+      :error -> :error
+    end
+  end
+
   defp cast_time(%{"hour" => empty, "minute" => empty}) when empty in ["", nil],
     do: {:ok, nil}
 

test/ecto/type_test.exs

@@ -532,6 +532,9 @@ defmodule Ecto.TypeTest do
 
       assert Ecto.Type.cast(:time, ~D[2016-11-11]) ==
                :error
+
+      assert Ecto.Type.cast(:time, @non_utc_datetime) ==
+               {:ok, ~T[22:30:07]}
     end
 
     test "dump" do
@@ -607,6 +610,8 @@ defmodule Ecto.TypeTest do
     test "cast from DateTime" do
       utc_datetime = DateTime.from_naive!(~N[2016-11-11 23:30:10], "Etc/UTC")
       assert Ecto.Type.cast(:time_usec, utc_datetime) == {:ok, ~T[23:30:10.000000]}
+
+      assert Ecto.Type.cast(:time_usec, @non_utc_datetime) == {:ok, ~T[22:30:07.008000]}
     end
 
     test "cast from Date" do