Merge pull request #4107 from robertwb/cdef-mixin

Allow inheriting from cimported multiply inherited class.

3 files changed, 74 insertions, 25 deletions

diff --git a/Cython/Compiler/Nodes.py b/Cython/Compiler/Nodes.py
index a095b2a72..5f935360f 100644
--- a/Cython/Compiler/Nodes.py
+++ b/Cython/Compiler/Nodes.py
@@ -5248,13 +5248,13 @@ class CClassDefNode(ClassDefNode):
                 self.type_init_args.generate_disposal_code(code)
                 self.type_init_args.free_temps(code)
 
-            self.generate_type_ready_code(self.entry, code, True)
+            self.generate_type_ready_code(self.entry, code)
         if self.body:
             self.body.generate_execution_code(code)
 
     # Also called from ModuleNode for early init types.
     @staticmethod
-    def generate_type_ready_code(entry, code, heap_type_bases=False):
+    def generate_type_ready_code(entry, code):
         # Generate a call to PyType_Ready for an extension
         # type defined in this module.
         type = entry.type
@@ -5290,15 +5290,10 @@ class CClassDefNode(ClassDefNode):
             code.putln("#else")
             for slot in TypeSlots.slot_table:
                 slot.generate_dynamic_init_code(scope, code)
-            if heap_type_bases:
-                code.globalstate.use_utility_code(
-                    UtilityCode.load_cached('PyType_Ready', 'ExtensionTypes.c'))
-                readyfunc = "__Pyx_PyType_Ready"
-            else:
-                readyfunc = "PyType_Ready"
+            code.globalstate.use_utility_code(
+                UtilityCode.load_cached('PyType_Ready', 'ExtensionTypes.c'))
             code.putln(
-                "if (%s(&%s) < 0) %s" % (
-                    readyfunc,
+                "if (__Pyx_PyType_Ready(&%s) < 0) %s" % (
                     typeobj_cname,
                     code.error_goto(entry.pos)))
             # Don't inherit tp_print from builtin types in Python 2, restoring the
@@ -5377,12 +5372,11 @@ class CClassDefNode(ClassDefNode):
                         type.vtabptr_cname,
                         code.error_goto(entry.pos)))
                 code.putln("#endif")
-                if heap_type_bases:
-                    code.globalstate.use_utility_code(
-                        UtilityCode.load_cached('MergeVTables', 'ImportExport.c'))
-                    code.putln("if (__Pyx_MergeVtables(&%s) < 0) %s" % (
-                        typeobj_cname,
-                        code.error_goto(entry.pos)))
+                code.globalstate.use_utility_code(
+                    UtilityCode.load_cached('MergeVTables', 'ImportExport.c'))
+                code.putln("if (__Pyx_MergeVtables(&%s) < 0) %s" % (
+                    typeobj_cname,
+                    code.error_goto(entry.pos)))
             if not type.scope.is_internal and not type.scope.directives.get('internal'):
                 # scope.is_internal is set for types defined by
                 # Cython (such as closures), the 'internal'
diff --git a/Cython/Utility/ExtensionTypes.c b/Cython/Utility/ExtensionTypes.c
index d8b8353cb..26bc2d9d9 100644
--- a/Cython/Utility/ExtensionTypes.c
+++ b/Cython/Utility/ExtensionTypes.c
@@ -3,6 +3,7 @@
 static int __Pyx_PyType_Ready(PyTypeObject *t);
 
 /////////////// PyType_Ready ///////////////
+//@requires: ObjectHandling.c::PyObjectCallNoArg
 
 // Wrapper around PyType_Ready() with some runtime checks and fixes
 // to deal with multiple inheritance.
@@ -67,24 +68,35 @@ static int __Pyx_PyType_Ready(PyTypeObject *t) {
         // For details, see https://github.com/cython/cython/issues/3603
         PyObject *ret, *py_status;
         int gc_was_enabled;
-        PyObject *gc = PyImport_Import(PYUNICODE("gc"));
-        if (unlikely(!gc)) return -1;
-        py_status = PyObject_CallMethodObjArgs(gc, PYUNICODE("isenabled"), NULL);
+        static PyObject *gc = NULL;
+        static PyObject *gc_isenabled = NULL, *gc_enable = NULL, *gc_disable = NULL;
+        if (unlikely(!gc)) {
+            gc = PyImport_Import(PYUNICODE("gc"));
+            if (unlikely(!gc)) return -1;
+            gc_isenabled = PyObject_GetAttr(gc, PYUNICODE("isenabled"));
+            gc_enable = PyObject_GetAttr(gc, PYUNICODE("enable"));
+            gc_disable = PyObject_GetAttr(gc, PYUNICODE("disable"));
+            if (unlikely(!gc_isenabled || !gc_enable || !gc_disable)) {
+              Py_XDECREF(gc_isenabled);  gc_isenabled = NULL;
+              Py_XDECREF(gc_enable);  gc_enable = NULL;
+              Py_XDECREF(gc_disable);  gc_disable = NULL;
+              Py_XDECREF(gc); gc = NULL;
+              return -1;
+            }
+        }
+        py_status = __Pyx_PyObject_CallNoArg(gc_isenabled);
         if (unlikely(!py_status)) {
-            Py_DECREF(gc);
             return -1;
         }
         gc_was_enabled = __Pyx_PyObject_IsTrue(py_status);
         Py_DECREF(py_status);
         if (gc_was_enabled > 0) {
-            ret = PyObject_CallMethodObjArgs(gc, PYUNICODE("disable"), NULL);
+            ret = __Pyx_PyObject_CallNoArg(gc_disable);
             if (unlikely(!ret)) {
-                Py_DECREF(gc);
                 return -1;
             }
             Py_DECREF(ret);
         } else if (unlikely(gc_was_enabled == -1)) {
-            Py_DECREF(gc);
             return -1;
         }
 
@@ -106,7 +118,7 @@ static int __Pyx_PyType_Ready(PyTypeObject *t) {
         if (gc_was_enabled) {
             PyObject *t, *v, *tb;
             PyErr_Fetch(&t, &v, &tb);
-            ret = PyObject_CallMethodObjArgs(gc, PYUNICODE("enable"), NULL);
+            ret = __Pyx_PyObject_CallNoArg(gc_enable);
             if (likely(ret || r == -1)) {
                 Py_XDECREF(ret);
                 // do not overwrite exceptions raised by PyType_Ready() above
@@ -119,7 +131,6 @@ static int __Pyx_PyType_Ready(PyTypeObject *t) {
                 r = -1;
             }
         }
-        Py_DECREF(gc);
     }
 #endif
 
diff --git a/tests/run/cdef_multiple_inheritance_cimport.srctree b/tests/run/cdef_multiple_inheritance_cimport.srctree
new file mode 100644
index 000000000..dd56b3e30
--- /dev/null
+++ b/tests/run/cdef_multiple_inheritance_cimport.srctree
@@ -0,0 +1,44 @@
+# Test for https://github.com/cython/cython/issues/4106
+
+PYTHON setup.py build_ext --inplace
+PYTHON -c "import sub"
+
+######## setup.py ########
+
+from Cython.Build import cythonize
+from distutils.core import setup
+
+setup(
+  ext_modules = cythonize("*.pyx"),
+)
+
+######## base.pxd ########
+
+cdef class A:
+  cdef dict __dict__
+  cdef int a(self)
+
+cdef class B(A):
+  cdef int b(self)
+
+######## base.pyx ########
+
+cdef class A:
+  cdef int a(self):
+    return 1
+
+class PyA:
+  pass
+
+cdef class B(A, PyA):
+  cdef int b(self):
+    return 2
+
+######## sub.pyx ########
+
+from base cimport B
+print(B)
+
+cdef class C(B):
+  cdef int c(self):
+    return 3