Add support for Python 3.10

Fixs #236 and fixes #237

Locally, the python.org installer for macOS 3.10.0b1 is crashing on the test suite, but versions I've built myself are fine. I'm still trying to figure out what's going on.

Author: jamadden

.github/workflows/tests.yml

@@ -23,7 +23,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9]
+        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9, 3.10.0-beta.1]
         os: [ubuntu-latest, macos-latest]
     steps:
     - uses: actions/checkout@v2
@@ -95,10 +95,17 @@ jobs:
         #run: |
         #  docker run --rm --privileged multiarch/qemu-user-static:register --reset
       - name: Build and test greenlet
+        if: matrix.image == 'manylinux2010_x86_64'
         # An alternate way to do this is to run the container directly with a uses:
         # and then the script runs inside it. That may work better with caching.
         # See https://github.com/pyca/bcrypt/blob/f6b5ee2eda76d077c531362ac65e16f045cf1f29/.github/workflows/wheel-builder.yml
-        # The 2010 image is the last one that comes with Python 2.7.
+        # The 2010 image is the last one that comes with Python 2.7,
+        # and only up through the tag 2021-02-06-3d322a5
+        env:
+          DOCKER_IMAGE: quay.io/pypa/${{ matrix.image }}:2021-02-06-3d322a5
+        run: bash ./make-manylinux
+      - name: Build and test greenlet (other)
+        if: matrix.image != 'manylinux2010_x86_64'
         env:
           DOCKER_IMAGE: quay.io/pypa/${{ matrix.image }}
         run: bash ./make-manylinux

CHANGES.rst

@@ -2,10 +2,11 @@
  Changes
 =========
 
-1.0.1 (unreleased)
+1.1.0 (unreleased)
 ==================
 
-- Nothing changed yet.
+- Add support for Python 3.10. Pre-built binary wheels are not
+  currently available for 3.10.
 
 
 1.0.0 (2021-01-13)

setup.py

@@ -138,6 +138,7 @@ def get_greenlet_version():
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
+        'Programming Language :: Python :: 3.10',
         'Operating System :: OS Independent',
         'Topic :: Software Development :: Libraries :: Python Modules'
     ],

src/greenlet/greenlet.c

@@ -96,6 +96,16 @@ extern PyTypeObject PyGreenlet_Type;
 #    define GREENLET_PY37 0
 #endif
 
+#if PY_VERSION_HEX >= 0x30A00B1
+/*
+Python 3.10 beta 1 changed tstate->use_tracing to a nested cframe member.
+See https://github.com/python/cpython/pull/25276
+*/
+#define TSTATE_USE_TRACING(tstate) (tstate->cframe->use_tracing)
+#else
+#define TSTATE_USE_TRACING(tstate) (tstate->use_tracing)
+#endif
+
 #ifndef Py_SET_REFCNT
 /* Py_REFCNT and Py_SIZE macros are converted to functions
 https://bugs.python.org/issue39573 */
@@ -567,10 +577,10 @@ g_calltrace(PyObject* tracefunc, PyObject* event, PyGreenlet* origin,
     PyErr_Fetch(&exc_type, &exc_val, &exc_tb);
     tstate = PyThreadState_GET();
     tstate->tracing++;
-    tstate->use_tracing = 0;
+    TSTATE_USE_TRACING(tstate) = 0;
     retval = PyObject_CallFunction(tracefunc, "O(OO)", event, origin, target);
     tstate->tracing--;
-    tstate->use_tracing =
+    TSTATE_USE_TRACING(tstate) =
         (tstate->tracing <= 0 &&
          ((tstate->c_tracefunc != NULL) || (tstate->c_profilefunc != NULL)));
     if (retval == NULL) {

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py27,py35,py36,py37,py38,py39,docs
+    py27,py35,py36,py37,py38,py39,py310,docs
 
 [testenv]
 commands =