DEP: finish making all comparisons to NaT false

Closes gh-11945

2 files changed, 26 insertions, 82 deletions

diff --git a/numpy/core/src/umath/loops.c.src b/numpy/core/src/umath/loops.c.src
index 66b69f555..e62942efd 100644
--- a/numpy/core/src/umath/loops.c.src
+++ b/numpy/core/src/umath/loops.c.src
@@ -1327,27 +1327,12 @@ NPY_NO_EXPORT void
 NPY_NO_EXPORT void
 @TYPE@_@kind@(char **args, npy_intp *dimensions, npy_intp *steps, void *NPY_UNUSED(func))
 {
-    npy_bool give_future_warning = 0;
     BINARY_LOOP {
         const @type@ in1 = *(@type@ *)ip1;
         const @type@ in2 = *(@type@ *)ip2;
-        const npy_bool res = in1 @OP@ in2;
-        *((npy_bool *)op1) = res;
-
-        if ((in1 == NPY_DATETIME_NAT || in2 == NPY_DATETIME_NAT) && res) {
-            give_future_warning = 1;
-        }
-    }
-    if (give_future_warning) {
-        NPY_ALLOW_C_API_DEF
-        NPY_ALLOW_C_API;
-        /* 2016-01-18, 1.11 */
-        if (DEPRECATE_FUTUREWARNING(
-                "In the future, 'NAT @OP@ x' and 'x @OP@ NAT' "
-                "will always be False.") < 0) {
-            /* nothing to do, we return anyway */
-        }
-        NPY_DISABLE_C_API;
+        *((npy_bool *)op1) = (in1 @OP@ in2 &&
+                              in1 != NPY_DATETIME_NAT &&
+                              in2 != NPY_DATETIME_NAT);
     }
 }
 /**end repeat1**/
@@ -1355,26 +1340,12 @@ NPY_NO_EXPORT void
 NPY_NO_EXPORT void
 @TYPE@_not_equal(char **args, npy_intp *dimensions, npy_intp *steps, void *NPY_UNUSED(func))
 {
-    npy_bool give_future_warning = 0;
     BINARY_LOOP {
         const @type@ in1 = *(@type@ *)ip1;
         const @type@ in2 = *(@type@ *)ip2;
-        *((npy_bool *)op1) = in1 != in2;
-
-        if (in1 == NPY_DATETIME_NAT && in2 == NPY_DATETIME_NAT) {
-            give_future_warning = 1;
-        }
-    }
-    if (give_future_warning) {
-        NPY_ALLOW_C_API_DEF
-        NPY_ALLOW_C_API;
-        /* 2016-01-18, 1.11 */
-        if (DEPRECATE_FUTUREWARNING(
-                "In the future, NAT != NAT will be True "
-                "rather than False.") < 0) {
-            /* nothing to do, we return anyway */
-        }
-        NPY_DISABLE_C_API;
+        *((npy_bool *)op1) = (in1 != in2 ||
+                              in1 == NPY_DATETIME_NAT ||
+                              in2 == NPY_DATETIME_NAT);
     }
 }
 
diff --git a/numpy/core/tests/test_datetime.py b/numpy/core/tests/test_datetime.py
index a5e1f73ce..c4918f955 100644
--- a/numpy/core/tests/test_datetime.py
+++ b/numpy/core/tests/test_datetime.py
@@ -7,7 +7,7 @@ import numpy as np
 import datetime
 import pytest
 from numpy.testing import (
-    assert_, assert_equal, assert_raises, assert_warns, suppress_warnings
+    assert_, assert_equal, assert_raises, assert_warns, suppress_warnings,
     )
 
 # Use pytz to test out various time zones if available
@@ -130,13 +130,10 @@ class TestDateTime(object):
 
     def test_compare_generic_nat(self):
         # regression tests for gh-6452
-        assert_equal(np.datetime64('NaT'),
-                     np.datetime64('2000') + np.timedelta64('NaT'))
-        # nb. we may want to make NaT != NaT true in the future
-        with suppress_warnings() as sup:
-            sup.filter(FutureWarning, ".*NAT ==")
-            assert_(np.datetime64('NaT') == np.datetime64('NaT', 'us'))
-            assert_(np.datetime64('NaT', 'us') == np.datetime64('NaT'))
+        assert_(np.datetime64('NaT') !=
+                np.datetime64('2000') + np.timedelta64('NaT'))
+        assert_(np.datetime64('NaT') != np.datetime64('NaT', 'us'))
+        assert_(np.datetime64('NaT', 'us') != np.datetime64('NaT'))
 
     def test_datetime_scalar_construction(self):
         # Construct with different units
@@ -1154,47 +1151,23 @@ class TestDateTime(object):
         td_nat = np.timedelta64('NaT', 'h')
         td_other = np.timedelta64(1, 'h')
 
-        with suppress_warnings() as sup:
-            # The assert warns contexts will again see the warning:
-            sup.filter(FutureWarning, ".*NAT")
-
-            for op in [np.equal, np.less, np.less_equal,
-                       np.greater, np.greater_equal]:
-                if op(dt_nat, dt_nat):
-                    assert_warns(FutureWarning, op, dt_nat, dt_nat)
-                if op(dt_nat, dt_other):
-                    assert_warns(FutureWarning, op, dt_nat, dt_other)
-                if op(dt_other, dt_nat):
-                    assert_warns(FutureWarning, op, dt_other, dt_nat)
-                if op(td_nat, td_nat):
-                    assert_warns(FutureWarning, op, td_nat, td_nat)
-                if op(td_nat, td_other):
-                    assert_warns(FutureWarning, op, td_nat, td_other)
-                if op(td_other, td_nat):
-                    assert_warns(FutureWarning, op, td_other, td_nat)
-
-            assert_warns(FutureWarning, np.not_equal, dt_nat, dt_nat)
-            assert_warns(FutureWarning, np.not_equal, td_nat, td_nat)
-
-        with suppress_warnings() as sup:
-            sup.record(FutureWarning)
-            assert_(np.not_equal(dt_nat, dt_other))
-            assert_(np.not_equal(dt_other, dt_nat))
-            assert_(np.not_equal(td_nat, td_other))
-            assert_(np.not_equal(td_other, td_nat))
-            assert_equal(len(sup.log), 0)
-
-    def test_datetime_futurewarning_once_nat(self):
-        # Test that the futurewarning is only given once per inner loop
-        arr1 = np.array(['NaT', 'NaT', '2000-01-01'] * 2, dtype='M8[s]')
-        arr2 = np.array(['NaT', '2000-01-01', 'NaT'] * 2, dtype='M8[s]')
-        # All except less, because for less it can't be wrong (NaT is min)
         for op in [np.equal, np.less, np.less_equal,
                    np.greater, np.greater_equal]:
-            with suppress_warnings() as sup:
-                rec = sup.record(FutureWarning, ".*NAT")
-                op(arr1, arr2)
-                assert_(len(rec) == 1, "failed for {}".format(op))
+            assert_(not op(dt_nat, dt_nat))
+            assert_(not op(dt_nat, dt_other))
+            assert_(not op(dt_other, dt_nat))
+
+            assert_(not op(td_nat, td_nat))
+            assert_(not op(td_nat, td_other))
+            assert_(not op(td_other, td_nat))
+
+        assert_(np.not_equal(dt_nat, dt_nat))
+        assert_(np.not_equal(dt_nat, dt_other))
+        assert_(np.not_equal(dt_other, dt_nat))
+
+        assert_(np.not_equal(td_nat, td_nat))
+        assert_(np.not_equal(td_nat, td_other))
+        assert_(np.not_equal(td_other, td_nat))
 
     def test_datetime_minmax(self):
         # The metadata of the result should become the GCD