gh-76785: Return an "excinfo" Object From Interpreter.run() (gh-111573)

Author: ericsnowcurrently

Include/internal/pycore_crossinterp.h

@@ -170,9 +170,14 @@ extern void _PyXI_Fini(PyInterpreterState *interp);
 // of the exception in the calling interpreter.
 
 typedef struct _excinfo {
-    const char *type;
+    struct _excinfo_type {
+        PyTypeObject *builtin;
+        const char *name;
+        const char *qualname;
+        const char *module;
+    } type;
     const char *msg;
-} _Py_excinfo;
+} _PyXI_excinfo;
 
 
 typedef enum error_code {
@@ -193,13 +198,13 @@ typedef struct _sharedexception {
     // The kind of error to propagate.
     _PyXI_errcode code;
     // The exception information to propagate, if applicable.
-    // This is populated only for _PyXI_ERR_UNCAUGHT_EXCEPTION.
-    _Py_excinfo uncaught;
-} _PyXI_exception_info;
+    // This is populated only for some error codes,
+    // but always for _PyXI_ERR_UNCAUGHT_EXCEPTION.
+    _PyXI_excinfo uncaught;
+} _PyXI_error;
+
+PyAPI_FUNC(PyObject *) _PyXI_ApplyError(_PyXI_error *err);
 
-PyAPI_FUNC(void) _PyXI_ApplyExceptionInfo(
-    _PyXI_exception_info *info,
-    PyObject *exctype);
 
 typedef struct xi_session _PyXI_session;
 typedef struct _sharedns _PyXI_namespace;
@@ -251,13 +256,13 @@ struct xi_session {
 
     // This is set if the interpreter is entered and raised an exception
     // that needs to be handled in some special way during exit.
-    _PyXI_errcode *exc_override;
+    _PyXI_errcode *error_override;
     // This is set if exit captured an exception to propagate.
-    _PyXI_exception_info *exc;
+    _PyXI_error *error;
 
     // -- pre-allocated memory --
-    _PyXI_exception_info _exc;
-    _PyXI_errcode _exc_override;
+    _PyXI_error _error;
+    _PyXI_errcode _error_override;
 };
 
 PyAPI_FUNC(int) _PyXI_Enter(
@@ -266,9 +271,7 @@ PyAPI_FUNC(int) _PyXI_Enter(
     PyObject *nsupdates);
 PyAPI_FUNC(void) _PyXI_Exit(_PyXI_session *session);
 
-PyAPI_FUNC(void) _PyXI_ApplyCapturedException(
-    _PyXI_session *session,
-    PyObject *excwrapper);
+PyAPI_FUNC(PyObject *) _PyXI_ApplyCapturedException(_PyXI_session *session);
 PyAPI_FUNC(int) _PyXI_HasCapturedException(_PyXI_session *session);
 
 

Lib/test/support/interpreters.py

@@ -14,13 +14,27 @@
 
 __all__ = [
     'Interpreter', 'get_current', 'get_main', 'create', 'list_all',
+    'RunFailedError',
     'SendChannel', 'RecvChannel',
     'create_channel', 'list_all_channels', 'is_shareable',
     'ChannelError', 'ChannelNotFoundError',
     'ChannelEmptyError',
     ]
 
 
+class RunFailedError(RuntimeError):
+
+    def __init__(self, excinfo):
+        msg = excinfo.formatted
+        if not msg:
+            if excinfo.type and snapshot.msg:
+                msg = f'{snapshot.type.__name__}: {snapshot.msg}'
+            else:
+                msg = snapshot.type.__name__ or snapshot.msg
+        super().__init__(msg)
+        self.snapshot = excinfo
+
+
 def create(*, isolated=True):
     """Return a new (idle) Python interpreter."""
     id = _interpreters.create(isolated=isolated)
@@ -110,7 +124,9 @@ def run(self, src_str, /, channels=None):
         that time, the previous interpreter is allowed to run
         in other threads.
         """
-        _interpreters.exec(self._id, src_str, channels)
+        excinfo = _interpreters.exec(self._id, src_str, channels)
+        if excinfo is not None:
+            raise RunFailedError(excinfo)
 
 
 def create_channel():

Lib/test/test__xxinterpchannels.py

@@ -1017,16 +1017,16 @@ def test_close_multiple_users(self):
             _channels.recv({cid})
             """))
         channels.close(cid)
-        with self.assertRaises(interpreters.RunFailedError) as cm:
-            interpreters.run_string(id1, dedent(f"""
+
+        excsnap = interpreters.run_string(id1, dedent(f"""
                 _channels.send({cid}, b'spam')
                 """))
-        self.assertIn('ChannelClosedError', str(cm.exception))
-        with self.assertRaises(interpreters.RunFailedError) as cm:
-            interpreters.run_string(id2, dedent(f"""
+        self.assertEqual(excsnap.type.__name__, 'ChannelClosedError')
+
+        excsnap = interpreters.run_string(id2, dedent(f"""
                 _channels.send({cid}, b'spam')
                 """))
-        self.assertIn('ChannelClosedError', str(cm.exception))
+        self.assertEqual(excsnap.type.__name__, 'ChannelClosedError')
 
     def test_close_multiple_times(self):
         cid = channels.create()

Lib/test/test__xxsubinterpreters.py

@@ -940,7 +940,6 @@ def add_module(self, modname, text):
         return script_helper.make_script(tempdir, modname, text)
 
     def run_script(self, text, *, fails=False):
-        excwrapper = interpreters.RunFailedError
         r, w = os.pipe()
         try:
             script = dedent(f"""
@@ -956,11 +955,12 @@ class NeverError(Exception): pass
                 raise NeverError  # never raised
                 """).format(dedent(text))
             if fails:
-                with self.assertRaises(excwrapper) as caught:
-                    interpreters.run_string(self.id, script)
-                return caught.exception
+                err = interpreters.run_string(self.id, script)
+                self.assertIsNot(err, None)
+                return err
             else:
-                interpreters.run_string(self.id, script)
+                err = interpreters.run_string(self.id, script)
+                self.assertIs(err, None)
                 return None
         except:
             raise  # re-raise
@@ -979,17 +979,18 @@ def _assert_run_failed(self, exctype, msg, script):
             exctype_name = exctype.__name__
 
         # Run the script.
-        exc = self.run_script(script, fails=True)
+        excinfo = self.run_script(script, fails=True)
 
         # Check the wrapper exception.
+        self.assertEqual(excinfo.type.__name__, exctype_name)
         if msg is None:
-            self.assertEqual(str(exc).split(':')[0],
+            self.assertEqual(excinfo.formatted.split(':')[0],
                              exctype_name)
         else:
-            self.assertEqual(str(exc),
+            self.assertEqual(excinfo.formatted,
                              '{}: {}'.format(exctype_name, msg))
 
-        return exc
+        return excinfo
 
     def assert_run_failed(self, exctype, script):
         self._assert_run_failed(exctype, None, script)

Lib/test/test_import/__init__.py

@@ -1968,10 +1968,12 @@ def test_disallowed_reimport(self):
             print(_testsinglephase)
             ''')
         interpid = _interpreters.create()
-        with self.assertRaises(_interpreters.RunFailedError):
-            _interpreters.run_string(interpid, script)
-        with self.assertRaises(_interpreters.RunFailedError):
-            _interpreters.run_string(interpid, script)
+
+        excsnap = _interpreters.run_string(interpid, script)
+        self.assertIsNot(excsnap, None)
+
+        excsnap = _interpreters.run_string(interpid, script)
+        self.assertIsNot(excsnap, None)
 
 
 class TestSinglePhaseSnapshot(ModuleSnapshot):

Lib/test/test_importlib/test_util.py

@@ -655,25 +655,19 @@ def test_magic_number(self):
 @unittest.skipIf(_interpreters is None, 'subinterpreters required')
 class IncompatibleExtensionModuleRestrictionsTests(unittest.TestCase):
 
-    ERROR = re.compile("^ImportError: module (.*) does not support loading in subinterpreters")
-
     def run_with_own_gil(self, script):
         interpid = _interpreters.create(isolated=True)
-        try:
-            _interpreters.run_string(interpid, script)
-        except _interpreters.RunFailedError as exc:
-            if m := self.ERROR.match(str(exc)):
-                modname, = m.groups()
-                raise ImportError(modname)
+        excsnap = _interpreters.run_string(interpid, script)
+        if excsnap is not None:
+            if excsnap.type.__name__ == 'ImportError':
+                raise ImportError(excsnap.msg)
 
     def run_with_shared_gil(self, script):
         interpid = _interpreters.create(isolated=False)
-        try:
-            _interpreters.run_string(interpid, script)
-        except _interpreters.RunFailedError as exc:
-            if m := self.ERROR.match(str(exc)):
-                modname, = m.groups()
-                raise ImportError(modname)
+        excsnap = _interpreters.run_string(interpid, script)
+        if excsnap is not None:
+            if excsnap.type.__name__ == 'ImportError':
+                raise ImportError(excsnap.msg)
 
     @unittest.skipIf(_testsinglephase is None, "test requires _testsinglephase module")
     def test_single_phase_init_module(self):

Lib/test/test_interpreters.py

@@ -478,6 +478,11 @@ def test_success(self):
 
         self.assertEqual(out, 'it worked!')
 
+    def test_failure(self):
+        interp = interpreters.create()
+        with self.assertRaises(interpreters.RunFailedError):
+            interp.run('raise Exception')
+
     def test_in_thread(self):
         interp = interpreters.create()
         script, file = _captured_script('print("it worked!", end="")')