implement second-level type resolution for literals

Added additional rule to the system that determines ``TypeEngine``
implementations from Python literals to apply a second level of adjustment
to the type, so that a Python datetime with or without tzinfo can set the
``timezone=True`` parameter on the returned :class:`.DateTime` object, as
well as :class:`.Time`. This helps with some round-trip scenarios on
type-sensitive PostgreSQL dialects such as asyncpg, psycopg3 (2.0 only).

For 1.4 specifically, the backport improves support for asyncpg handling of
TIME WITH TIMEZONE, which was not fully implemented. 2.0's reworked
PostgreSQL architecture had this handled already.

Fixes: #7537
Change-Id: Icdb07db85af5f7f39f1c1ef855fe27609770094b

1 files changed, 28 insertions, 0 deletions

diff --git a/lib/sqlalchemy/testing/suite/test_types.py b/lib/sqlalchemy/testing/suite/test_types.py
index 78596457e..796de5d93 100644
--- a/lib/sqlalchemy/testing/suite/test_types.py
+++ b/lib/sqlalchemy/testing/suite/test_types.py
@@ -302,6 +302,11 @@ class _DateFixture(_LiteralRoundTripFixture, fixtures.TestBase):
             Column("decorated_date_data", Decorated),
         )
 
+    @testing.requires.datetime_implicit_bound
+    def test_select_direct(self, connection):
+        result = connection.scalar(select(literal(self.data)))
+        eq_(result, self.data)
+
     def test_round_trip(self, connection):
         date_table = self.tables.date_table
 
@@ -376,6 +381,15 @@ class DateTimeTest(_DateFixture, fixtures.TablesTest):
     data = datetime.datetime(2012, 10, 15, 12, 57, 18)
 
 
+class DateTimeTZTest(_DateFixture, fixtures.TablesTest):
+    __requires__ = ("datetime_timezone",)
+    __backend__ = True
+    datatype = DateTime(timezone=True)
+    data = datetime.datetime(
+        2012, 10, 15, 12, 57, 18, tzinfo=datetime.timezone.utc
+    )
+
+
 class DateTimeMicrosecondsTest(_DateFixture, fixtures.TablesTest):
     __requires__ = ("datetime_microseconds",)
     __backend__ = True
@@ -389,6 +403,11 @@ class TimestampMicrosecondsTest(_DateFixture, fixtures.TablesTest):
     datatype = TIMESTAMP
     data = datetime.datetime(2012, 10, 15, 12, 57, 18, 396)
 
+    @testing.requires.timestamp_microseconds_implicit_bound
+    def test_select_direct(self, connection):
+        result = connection.scalar(select(literal(self.data)))
+        eq_(result, self.data)
+
 
 class TimeTest(_DateFixture, fixtures.TablesTest):
     __requires__ = ("time",)
@@ -397,6 +416,13 @@ class TimeTest(_DateFixture, fixtures.TablesTest):
     data = datetime.time(12, 57, 18)
 
 
+class TimeTZTest(_DateFixture, fixtures.TablesTest):
+    __requires__ = ("time_timezone",)
+    __backend__ = True
+    datatype = Time(timezone=True)
+    data = datetime.time(12, 57, 18, tzinfo=datetime.timezone.utc)
+
+
 class TimeMicrosecondsTest(_DateFixture, fixtures.TablesTest):
     __requires__ = ("time_microseconds",)
     __backend__ = True
@@ -1515,6 +1541,7 @@ __all__ = (
     "JSONLegacyStringCastIndexTest",
     "DateTest",
     "DateTimeTest",
+    "DateTimeTZTest",
     "TextTest",
     "NumericTest",
     "IntegerTest",
@@ -1524,6 +1551,7 @@ __all__ = (
     "TimeMicrosecondsTest",
     "TimestampMicrosecondsTest",
     "TimeTest",
+    "TimeTZTest",
     "TrueDivTest",
     "DateTimeMicrosecondsTest",
     "DateHistoricTest",