Closes issue #24773: Implement PEP 495 (Local Time Disambiguation).

Include/datetime.h

@@ -81,6 +81,7 @@ typedef struct
 typedef struct
 {
     _PyDateTime_TIMEHEAD
+    unsigned char fold;
     PyObject *tzinfo;
 } PyDateTime_Time;              /* hastzinfo true */
 
@@ -108,6 +109,7 @@ typedef struct
 typedef struct
 {
     _PyDateTime_DATETIMEHEAD
+    unsigned char fold;
     PyObject *tzinfo;
 } PyDateTime_DateTime;          /* hastzinfo true */
 
@@ -125,6 +127,7 @@ typedef struct
     ((((PyDateTime_DateTime*)o)->data[7] << 16) |       \
      (((PyDateTime_DateTime*)o)->data[8] << 8)  |       \
       ((PyDateTime_DateTime*)o)->data[9])
+#define PyDateTime_DATE_GET_FOLD(o)        (((PyDateTime_DateTime*)o)->fold)
 
 /* Apply for time instances. */
 #define PyDateTime_TIME_GET_HOUR(o)        (((PyDateTime_Time*)o)->data[0])
@@ -134,6 +137,7 @@ typedef struct
     ((((PyDateTime_Time*)o)->data[3] << 16) |           \
      (((PyDateTime_Time*)o)->data[4] << 8)  |           \
       ((PyDateTime_Time*)o)->data[5])
+#define PyDateTime_TIME_GET_FOLD(o)        (((PyDateTime_Time*)o)->fold)
 
 /* Apply for time delta instances */
 #define PyDateTime_DELTA_GET_DAYS(o)         (((PyDateTime_Delta*)o)->days)
@@ -162,6 +166,11 @@ typedef struct {
     PyObject *(*DateTime_FromTimestamp)(PyObject*, PyObject*, PyObject*);
     PyObject *(*Date_FromTimestamp)(PyObject*, PyObject*);
 
+    /* PEP 495 constructors */
+    PyObject *(*DateTime_FromDateAndTimeAndFold)(int, int, int, int, int, int, int,
+        PyObject*, int, PyTypeObject*);
+    PyObject *(*Time_FromTimeAndFold)(int, int, int, int, PyObject*, int, PyTypeObject*);
+
 } PyDateTime_CAPI;
 
 #define PyDateTime_CAPSULE_NAME "datetime.datetime_CAPI"
@@ -217,10 +226,18 @@ static PyDateTime_CAPI *PyDateTimeAPI = NULL;
     PyDateTimeAPI->DateTime_FromDateAndTime(year, month, day, hour, \
         min, sec, usec, Py_None, PyDateTimeAPI->DateTimeType)
 
+#define PyDateTime_FromDateAndTimeAndFold(year, month, day, hour, min, sec, usec, fold) \
+    PyDateTimeAPI->DateTime_FromDateAndTimeAndFold(year, month, day, hour, \
+        min, sec, usec, Py_None, fold, PyDateTimeAPI->DateTimeType)
+
 #define PyTime_FromTime(hour, minute, second, usecond) \
     PyDateTimeAPI->Time_FromTime(hour, minute, second, usecond, \
         Py_None, PyDateTimeAPI->TimeType)
 
+#define PyTime_FromTimeAndFold(hour, minute, second, usecond, fold) \
+    PyDateTimeAPI->Time_FromTimeAndFold(hour, minute, second, usecond, \
+        Py_None, fold, PyDateTimeAPI->TimeType)
+
 #define PyDelta_FromDSU(days, seconds, useconds) \
     PyDateTimeAPI->Delta_FromDelta(days, seconds, useconds, 1, \
         PyDateTimeAPI->DeltaType)