Fix #385

CHANGES.rst

@@ -5,7 +5,9 @@
 3.0.2 (unreleased)
 ==================
 
-- Nothing changed yet.
+- Fix a test case on Arm32. Note that this is not a supported platform
+  (there is no CI for it) and support is best effort; there may be
+  other issues lurking. See `issue 385 <https://github.com/python-greenlet/greenlet/issues/385>`_
 
 
 3.0.1 (2023-10-25)

src/greenlet/TUserGreenlet.cpp

@@ -314,7 +314,11 @@ UserGreenlet::g_initialstub(void* mark)
         // Getting a C++ exception here isn't good. It's probably a
         // bug in the underlying greenlet, meaning it's probably a
         // C++ extension. We're going to abort anyway, but try to
-        // display some nice information if possible.
+        // display some nice information *if* possible. Some obscure
+        // platforms don't properly support this (old 32-bit Arm, see see
+        // https://github.com/python-greenlet/greenlet/issues/385); that's not
+        // great, but should usually be OK because, as mentioned above, we're
+        // terminating anyway.
         //
         // The catching is tested by
         // ``test_cpp.CPPTests.test_unhandled_exception_in_greenlet_aborts``.

src/greenlet/tests/test_cpp.py

@@ -56,7 +56,11 @@ def test_unhandled_std_exception_as_greenlet_function_aborts(self):
         # verify that plain unhandled throw aborts
         output = self._do_test_unhandled_exception('run_as_greenlet_target')
         self.assertIn(
-            'greenlet: Unhandled C++ exception: Thrown from an extension.',
+            # We really expect this to be prefixed with "greenlet: Unhandled C++ exception:"
+            # as added by our handler for std::exception (see TUserGreenlet.cpp), but
+            # that's not correct everywhere --- our handler never runs before std::terminate
+            # gets called (for example, on arm32).
+            'Thrown from an extension.',
             output
         )