Trac #30184: Support Python 3.9

We should support Python 3.9 (expected to be released 2020-10-05) in Sage 9.2. The present ticket is for the patches necessary to support Python 3.9 in addition to 3.7 and 3.8. It does not include the actual upgrade to Python 3.9 - to test, merge #30589. - [https://www.python.org/dev/peps/pep-0596/ Python 3.9 release schedule] - [https://docs.python.org/3.9/whatsnew/3.9.html What's new in Python 3.9] - #30384 Adopt the “time window-based” policy for support of Python versions from NEP 29 URL: https://trac.sagemath.org/30184 Reported by: slelievre Ticket author(s): Matthias Koeppe Reviewer(s): John Palmieri, Dima Pasechnik
sagemath · Oct 3, 2020 · 91eac29 · 91eac29
2 parents a1810d5 + 9d06080
commit 91eac29
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diff --git a/build/pkgs/configure/checksums.ini b/build/pkgs/configure/checksums.ini
@@ -1,4 +1,4 @@
 tarball=configure-VERSION.tar.gz
-sha1=2d1d5ab6f12d7181f246eacec7b2fb1e1338b9ed
-md5=4c9d6a5ed4f1b2494187fe043a15214b
-cksum=3219488233
+sha1=855a9093485a5f2c04054f4d30251b5bb4e92306
+md5=e4b0af774d072208429fefcb2d367123
+cksum=4201841578
diff --git a/build/pkgs/configure/package-version.txt b/build/pkgs/configure/package-version.txt
@@ -1 +1 @@
-be1a62b3bc99666c909f3672a8bf7baf32a15404
+68799277f8eeb04a1201472378e1f71f4f016d71
diff --git a/build/pkgs/python3/spkg-configure.m4 b/build/pkgs/python3/spkg-configure.m4
@@ -16,7 +16,7 @@ SAGE_SPKG_CONFIGURE([python3], [
       dnl instead of building our own copy.
       check_modules="sqlite3, ctypes, math, hashlib, crypt, readline, socket, zlib, distutils.core"
       m4_pushdef([MIN_VERSION], [3.6.0])
-      m4_pushdef([LT_VERSION],  [3.9.0])
+      m4_pushdef([LT_VERSION],  [3.10.0])
       AC_CACHE_CHECK([for python3 >= ]MIN_VERSION[, < ]LT_VERSION[ with modules $check_modules], [ac_cv_path_PYTHON3], [
         AS_IF([test x"$ac_path_PYTHON3" != x], [dnl checking explicitly specified $with_python
            AC_MSG_RESULT([])

diff --git a/src/sage/all.py b/src/sage/all.py
@@ -102,6 +102,11 @@
 # However, be sure to keep OUR deprecation warnings
 warnings.filterwarnings('default', category=DeprecationWarning,
     message=r'[\s\S]*See https\?://trac\.sagemath\.org/[0-9]* for details.')
+
+# Ignore Python 3.9 deprecation warnings
+warnings.filterwarnings('ignore', category=DeprecationWarning,
+    module='.*ast')
+
 ################ end setup warnings ###############################
 
 

diff --git a/src/sage/combinat/root_system/pieri_factors.py b/src/sage/combinat/root_system/pieri_factors.py
@@ -147,8 +147,8 @@ def elements(self):
         EXAMPLES::
 
             sage: PF = WeylGroup(['A',3]).pieri_factors()
-            sage: [w.reduced_word() for w in PF.elements()]
-            [[3, 2, 1], [2, 1], [3, 1], [3, 2], [2], [1], [3], []]
+            sage: sorted(w.reduced_word() for w in PF.elements())
+            [[], [1], [2], [2, 1], [3], [3, 1], [3, 2], [3, 2, 1]]
 
         .. SEEALSO:: :meth:`maximal_elements`
 

diff --git a/src/sage/cpython/debugimpl.c b/src/sage/cpython/debugimpl.c
@@ -1,5 +1,13 @@
 #include <stdio.h>
 
+#if PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION >= 9
+
+static void _type_debug(PyTypeObject* tp)
+{
+    printf("Not implemented for CPython >= 3.9\n");
+}
+
+#else
 
 #define HAVE_WEAKREFS(tp) (1)
 #define HAVE_CLASS(tp) (1)
@@ -340,3 +348,5 @@ static void _type_debug(PyTypeObject* tp)
         printf("  tp_version_tag: %lu\n", (unsigned long)tp->tp_version_tag);
     }
 }
+
+#endif
diff --git a/src/sage/geometry/polyhedron/palp_database.py b/src/sage/geometry/polyhedron/palp_database.py
@@ -131,7 +131,7 @@ def _palp_Popen(self):
             sage: from sage.geometry.polyhedron.palp_database import PALPreader
             sage: polygons = PALPreader(2)
             sage: polygons._palp_Popen()
-            <subprocess.Popen object at 0x...>
+            <...Popen...>
         """
 
         return Popen(["class.x", "-b2a", "-di", self._data_basename],
@@ -458,7 +458,7 @@ def _palp_Popen(self):
             sage: from sage.geometry.polyhedron.palp_database import Reflexive4dHodge
             sage: polygons = Reflexive4dHodge(1, 101)   # optional - polytopes_db_4d
             sage: polygons._palp_Popen()                # optional - polytopes_db_4d
-            <subprocess.Popen object at 0x...>
+            <...Popen...>
         """
 
         return Popen(['class-4d.x', '-He',

diff --git a/src/sage/misc/latex.py b/src/sage/misc/latex.py
@@ -556,7 +556,7 @@ def has_latex_attr(x):
         sage: T._latex_()
         Traceback (most recent call last):
         ...
-        TypeError: descriptor '_latex_' of 'sage.matrix.matrix0.Matrix' object needs an argument
+        TypeError: ..._latex_... needs an argument
         sage: has_latex_attr(T)
         False
     """

diff --git a/src/sage/misc/sageinspect.py b/src/sage/misc/sageinspect.py
@@ -426,7 +426,7 @@ class SageArgSpecVisitor(ast.NodeVisitor):
         sage: sorted(v.items(), key=lambda x: str(x[0]))
         [(37.0, 'temp'), ('a', ('e', 2, [None, ({False: True}, 'pi')]))]
         sage: v = ast.parse("jc = ['veni', 'vidi', 'vici']").body[0]; v
-        <_ast.Assign object at ...>
+        <...ast.Assign object at ...>
         sage: attrs = [x for x in dir(v) if not x.startswith('__')]
         sage: '_attributes' in attrs and '_fields' in attrs and 'col_offset' in attrs
         True
@@ -2273,7 +2273,7 @@ def sage_getsourcelines(obj):
           '    def __cinit__(self):\n',
         ...)
         sage: sage_getsourcelines(I)
-        (['class MPolynomialIdeal( MPolynomialIdeal_singular_repr, \\\n',
+        ([...'class MPolynomialIdeal( MPolynomialIdeal_singular_repr, \\\n',
         ...)
         sage: x = var('x')
         sage: sage_getsourcelines(x)
@@ -2318,7 +2318,7 @@ class Element(object):
         sage: P.<x,y> = QQ[]
         sage: I = P*[x,y]
         sage: sage_getsourcelines(I)
-        (['class MPolynomialIdeal( MPolynomialIdeal_singular_repr, \\\n',
+        ([...'class MPolynomialIdeal( MPolynomialIdeal_singular_repr, \\\n',
           '                        MPolynomialIdeal_macaulay2_repr, \\\n',
           '                        MPolynomialIdeal_magma_repr, \\\n',
           '                        Ideal_generic ):\n',

diff --git a/src/sage/symbolic/ring.pyx b/src/sage/symbolic/ring.pyx
@@ -33,7 +33,6 @@ from sage.rings.all import RR, CC, ZZ
 
 import keyword
 import operator
-import parser
 
 # Do not allow any of these keywords as identifiers for symbolic variables
 KEYWORDS = set(keyword.kwlist).union(['exec', 'print', 'None', 'True',
@@ -1380,7 +1379,7 @@ def isidentifier(x):
     Boolean. Whether the string ``x`` can be used as a variable name.
 
     This function should return ``False`` for keywords, so we can not
-    just use the ``isidentifier`` method of strings (in Python 3),
+    just use the ``isidentifier`` method of strings,
     because, for example, it returns ``True`` for "def" and for "None".
 
     EXAMPLES::
@@ -1409,15 +1408,4 @@ def isidentifier(x):
     """
     if x in KEYWORDS:
         return False
-    try:
-        if not x.isidentifier():  # py3
-            return False
-    except AttributeError:
-        pass  # py2
-
-    try:
-        code = parser.expr(x).compile()
-    except (MemoryError, OverflowError, SyntaxError,
-            SystemError, parser.ParserError):
-        return False
-    return len(code.co_names) == 1 and code.co_names[0] == x
+    return x.isidentifier()