bpo-39684: Combine two if/thens

Doc/library/functions.rst

@@ -1829,9 +1829,6 @@ are always available.  They are listed here in alphabetical order.
       Negative values for *level* are no longer supported (which also changes
       the default value to 0).
 
-   .. versionchanged:: 3.9
-      When the command line options :option:`-E` or :option:`-I` are being used,
-      the environment variable :envvar:`PYTHONCASEOK` is now ignored.
 
 .. rubric:: Footnotes
 

Doc/library/math.rst

@@ -136,6 +136,15 @@ Number-theoretic and representation functions
    .. versionadded:: 3.5
 
 
+.. function:: lcm(a, b)
+
+   Return the least common multiple of integers *a* and *b*.  The value of
+   ``lcm(a, b)`` is the smallest nonnegative integer that is a multiple of
+   both *a* and *b*.  If either *a* or *b* is zero then ``lcm(a, b)`` is zero.
+
+   .. versionadded:: 3.9
+
+
 .. function:: isclose(a, b, *, rel_tol=1e-09, abs_tol=0.0)
 
    Return ``True`` if the values *a* and *b* are close to each other and

Doc/library/typing.rst

@@ -996,8 +996,20 @@ The module defines the following classes, functions and decorators:
       Point2D = TypedDict('Point2D', x=int, y=int, label=str)
       Point2D = TypedDict('Point2D', {'x': int, 'y': int, 'label': str})
 
-   See :pep:`589` for more examples and detailed rules of using ``TypedDict``
-   with type checkers.
+   By default, all keys must be present in a TypedDict. It is possible
+   to override this by specifying totality.
+   Usage::
+
+      class point2D(TypedDict, total=False):
+          x: int
+          y: int
+
+   This means that a point2D TypedDict can have any of the keys omitted.A type
+   checker is only expected to support a literal False or True as the value of
+   the total argument. True is the default, and makes all items defined in the
+   class body be required.
+
+   See :pep:`589` for more examples and detailed rules of using ``TypedDict``.
 
    .. versionadded:: 3.8
 

Doc/whatsnew/3.9.rst

@@ -216,6 +216,9 @@ import attempts.
 math
 ----
 
+Add :func:`math.lcm`: return the least common multiple of *a* and *b*.
+(Contributed by Ananthakrishnan in :issue:`39479`.)
+
 Add :func:`math.nextafter`: return the next floating-point value after *x*
 towards *y*.
 (Contributed by Victor Stinner in :issue:`39288`.)
@@ -584,9 +587,6 @@ Changes in the Python API
   since the *buffering* parameter has been removed.
   (Contributed by Victor Stinner in :issue:`39357`.)
 
-* The :mod:`importlib` module now ignores the :envvar:`PYTHONCASEOK`
-  environment variable when the :option:`-E` or :option:`-I` command line
-  options are being used.
 
 CPython bytecode changes
 ------------------------

Lib/importlib/_bootstrap_external.py

@@ -35,7 +35,7 @@ def _make_relax_case():
 
         def _relax_case():
             """True if filenames must be checked case-insensitively."""
-            return not sys.flags.ignore_environment and key in _os.environ
+            return key in _os.environ
     else:
         def _relax_case():
             """True if filenames must be checked case-insensitively."""

Lib/test/test_math.py

@@ -974,6 +974,41 @@ def __index__(self):
                 with self.assertRaises(TypeError):
                     math.isqrt(value)
 
+    def test_lcm(self):
+        lcm = math.lcm
+        self.assertEqual(lcm(0, 0), 0)
+        self.assertEqual(lcm(1, 0), 0)
+        self.assertEqual(lcm(-1, 0), 0)
+        self.assertEqual(lcm(0, 1), 0)
+        self.assertEqual(lcm(0, -1), 0)
+        self.assertEqual(lcm(7, 1), 7)
+        self.assertEqual(lcm(7, -1), 7)
+        self.assertEqual(lcm(-23, 15), 345)
+        self.assertEqual(lcm(120, 84), 840)
+        self.assertEqual(lcm(84, -120), 840)
+        self.assertEqual(lcm(1216342683557601535506311712,
+                             436522681849110124616458784),
+                             16592536571065866494401400422922201534178938447014944)
+        x = 43461045657039990237
+        y = 10645022458251153277
+
+        for c in (652560,
+                  57655923087165495981):
+            a = x * c
+            b = y * c
+            d = x * y * c
+            self.assertEqual(lcm(a, b), d)
+            self.assertEqual(lcm(b, a), d)
+            self.assertEqual(lcm(-a, b), d)
+            self.assertEqual(lcm(b, -a), d)
+            self.assertEqual(lcm(a, -b), d)
+            self.assertEqual(lcm(-b, a), d)
+            self.assertEqual(lcm(-a, -b), d)
+            self.assertEqual(lcm(-b, -a), d)
+        self.assertEqual(lcm(MyIndexable(120), MyIndexable(84)), 840)
+        self.assertRaises(TypeError, lcm, 120.0, 84)
+        self.assertRaises(TypeError, lcm, 120, 84.0)
+
     def testLdexp(self):
         self.assertRaises(TypeError, math.ldexp)
         self.ftest('ldexp(0,1)', math.ldexp(0,1), 0)

Lib/typing.py

@@ -13,7 +13,7 @@
 * Public helper functions: get_type_hints, overload, cast, no_type_check,
   no_type_check_decorator.
 * Generic aliases for collections.abc ABCs and few additional protocols.
-* Special types: NewType, NamedTuple, TypedDict (may be added soon).
+* Special types: NewType, NamedTuple, TypedDict.
 * Wrapper submodules for re and io related types.
 """
 
@@ -1885,6 +1885,19 @@ class Point2D(TypedDict):
         Point2D = TypedDict('Point2D', x=int, y=int, label=str)
         Point2D = TypedDict('Point2D', {'x': int, 'y': int, 'label': str})
 
+    By default, all keys must be present in a TypedDict. It is possible
+    to override this by specifying totality.
+    Usage::
+
+        class point2D(TypedDict, total=False):
+            x: int
+            y: int
+
+    This means that a point2D TypedDict can have any of the keys omitted.A type
+    checker is only expected to support a literal False or True as the value of
+    the total argument. True is the default, and makes all items defined in the
+    class body be required.
+
     The class syntax is only supported in Python 3.6+, while two other
     syntax forms work for Python 2.7 and 3.2+
     """

Misc/ACKS

@@ -45,6 +45,7 @@ Rose Ames
 A. Amoroso
 Mark Anacker
 Shashwat Anand
+Ananthakrishnan
 Anders Andersen
 Tycho Andersen
 John Anderson

Misc/NEWS.d/next/Documentation/2020-02-18-18-37-07.bpo-39572.CCtzy1.rst

@@ -0,0 +1 @@
+Updated documentation of ``total`` flag of TypeDict.

Misc/NEWS.d/next/Library/2020-02-18-12-37-16.bpo-39479.j3UcCq.rst

@@ -0,0 +1 @@
+Add :func:`math.lcm` function: least common multiple.

Modules/mathmodule.c

@@ -2017,6 +2017,59 @@ math_factorial(PyObject *module, PyObject *arg)
 }
 
 
+/*[clinic input]
+math.lcm
+    x as a: object
+    y as b: object
+    /
+least common multiple of x and y
+[clinic start generated code]*/
+
+static PyObject *
+math_lcm_impl(PyObject *module, PyObject *a, PyObject *b)
+/*[clinic end generated code: output=6f83fb6d671074ba input=efb3d7b7334b7118]*/
+{
+    PyObject *g, *m, *f, *ab;
+
+    a = PyNumber_Index(a);
+    if (a == NULL) {
+        return NULL;
+    }
+    b = PyNumber_Index(b);
+    if (b == NULL) {
+        Py_DECREF(a);
+        return NULL;
+    }
+    if (_PyLong_Sign(a) == 0 || _PyLong_Sign(b) == 0) {
+        Py_DECREF(a);
+        Py_DECREF(b);
+        return PyLong_FromLong(0);
+    }
+    g = _PyLong_GCD(a, b);
+    if (g == NULL) {
+        Py_DECREF(a);
+        Py_DECREF(b);
+        return NULL;
+    }
+    f = PyNumber_FloorDivide(a, g);
+    Py_DECREF(g);
+    Py_DECREF(a);
+    if (f == NULL) {
+        Py_DECREF(b);
+        return NULL;
+    }
+    m = PyNumber_Multiply(f, b);
+    Py_DECREF(f);
+    Py_DECREF(b);
+    if (m == NULL) {
+        return NULL;
+    }
+    ab = PyNumber_Absolute(m);
+    Py_DECREF(m);
+    return ab;
+}
+
+
 /*[clinic input]
 math.trunc
 
@@ -3362,6 +3415,7 @@ static PyMethodDef math_methods[] = {
     MATH_ISINF_METHODDEF
     MATH_ISNAN_METHODDEF
     MATH_ISQRT_METHODDEF
+    MATH_LCM_METHODDEF
     MATH_LDEXP_METHODDEF
     {"lgamma",          math_lgamma,    METH_O,         math_lgamma_doc},
     MATH_LOG_METHODDEF

Objects/unicodeobject.c

@@ -12209,20 +12209,15 @@ PyUnicode_IsIdentifier(PyObject *self)
 
     int kind = 0;
     void *data = NULL;
-    wchar_t *wstr;
+    const wchar_t *wstr = NULL;
+    Py_UCS4 ch;
     if (ready) {
         kind = PyUnicode_KIND(self);
         data = PyUnicode_DATA(self);
-    }
-    else {
-        wstr = _PyUnicode_WSTR(self);
-    }
-
-    Py_UCS4 ch;
-    if (ready) {
         ch = PyUnicode_READ(kind, data, 0);
     }
     else {
+        wstr = _PyUnicode_WSTR(self);
         ch = wstr[0];
     }
     /* PEP 3131 says that the first character must be in