prevent simple builtin typed exttype attributes from triggering GC support

Cython/Compiler/PyrexTypes.py

@@ -859,6 +859,7 @@ class PyObjectType(PyrexType):
     buffer_defaults = None
     is_extern = False
     is_subclassed = False
+    is_gc_simple = False
 
     def __str__(self):
         return "Python object"
@@ -909,6 +910,12 @@ class PyObjectType(PyrexType):
         return cname
 
 
+builtin_types_that_cannot_create_refcycles = set([
+    'bool', 'int', 'long', 'float', 'complex',
+    'bytearray', 'bytes', 'unicode', 'str', 'basestring'
+])
+
+
 class BuiltinObjectType(PyObjectType):
     #  objstruct_cname  string           Name of PyObject struct
 
@@ -929,6 +936,7 @@ class BuiltinObjectType(PyObjectType):
         self.cname = cname
         self.typeptr_cname = "(&%s)" % cname
         self.objstruct_cname = objstruct_cname
+        self.is_gc_simple = name in builtin_types_that_cannot_create_refcycles
 
     def set_scope(self, scope):
         self.scope = scope

Cython/Compiler/Symtab.py

@@ -1769,6 +1769,7 @@ class CClassScope(ClassScope):
     #  method_table_cname    string
     #  getset_table_cname    string
     #  has_pyobject_attrs    boolean  Any PyObject attributes?
+    #  has_cyclic_pyobject_attrs    boolean  Any PyObject attributes that may need GC?
     #  property_entries      [Entry]
     #  defined               boolean  Defined in .pxd file
     #  implemented           boolean  Defined in .pyx file
@@ -1776,24 +1777,30 @@ class CClassScope(ClassScope):
 
     is_c_class_scope = 1
 
+    has_pyobject_attrs = False
+    has_cyclic_pyobject_attrs = False
+    defined = False
+    implemented = False
+
     def __init__(self, name, outer_scope, visibility):
         ClassScope.__init__(self, name, outer_scope)
         if visibility != 'extern':
             self.method_table_cname = outer_scope.mangle(Naming.methtab_prefix, name)
             self.getset_table_cname = outer_scope.mangle(Naming.gstab_prefix, name)
-        self.has_pyobject_attrs = 0
         self.property_entries = []
         self.inherited_var_entries = []
-        self.defined = 0
-        self.implemented = 0
 
     def needs_gc(self):
         # If the type or any of its base types have Python-valued
         # C attributes, then it needs to participate in GC.
-        return self.has_pyobject_attrs or \
-            (self.parent_type.base_type and
-                self.parent_type.base_type.scope is not None and
-                self.parent_type.base_type.scope.needs_gc())
+        if self.has_cyclic_pyobject_attrs:
+            return True
+        base_type = self.parent_type.base_type
+        if base_type and base_type.scope is not None:
+            return base_type.scope.needs_gc()
+        elif self.parent_type.is_builtin_type:
+            return not self.parent_type.is_gc_simple
+        return False
 
     def declare_var(self, name, type, pos,
                     cname = None, visibility = 'private',
@@ -1819,7 +1826,10 @@ class CClassScope(ClassScope):
             entry.is_variable = 1
             self.var_entries.append(entry)
             if type.is_pyobject and name != '__weakref__':
-                self.has_pyobject_attrs = 1
+                self.has_pyobject_attrs = True
+                if (not type.is_builtin_type
+                        or not type.scope or type.scope.needs_gc()):
+                    self.has_cyclic_pyobject_attrs = True
             if visibility not in ('private', 'public', 'readonly'):
                 error(pos,
                     "Attribute of extension type cannot be declared %s" % visibility)

Cython/Compiler/TypeSlots.py

@@ -319,10 +319,10 @@ class GCDependentSlot(InternalMethodSlot):
     def slot_code(self, scope):
         if not scope.needs_gc():
             return "0"
-        if not scope.has_pyobject_attrs:
-            # if the type does not have object attributes, it can
-            # delegate GC methods to its parent - iff the parent
-            # functions are defined in the same module
+        if not scope.has_cyclic_pyobject_attrs:
+            # if the type does not have GC relevant object attributes, it can
+            # delegate GC methods to its parent - iff the parent functions
+            # are defined in the same module
             parent_type_scope = scope.parent_type.base_type.scope
             if scope.parent_scope is parent_type_scope.parent_scope:
                 entry = scope.parent_scope.lookup_here(scope.parent_type.base_type.name)
@@ -339,10 +339,10 @@ class ConstructorSlot(InternalMethodSlot):
         self.method = method
 
     def slot_code(self, scope):
-        if self.slot_name != 'tp_new' \
-            and scope.parent_type.base_type \
-            and not scope.has_pyobject_attrs \
-            and not scope.lookup_here(self.method):
+        if (self.slot_name != 'tp_new'
+                and scope.parent_type.base_type
+                and not scope.has_pyobject_attrs
+                and not scope.lookup_here(self.method)):
             # if the type does not have object attributes, it can
             # delegate GC methods to its parent - iff the parent
             # functions are defined in the same module

tests/run/cyclic_gc.pyx

+# mode: run
+# tag: cyclicgc
+
+
+cimport cython
+
+@cython.test_fail_if_path_exists('//CClassDefNode[@scope.has_cyclic_pyobject_attrs = True]')
+@cython.test_assert_path_exists('//CClassDefNode',
+                                '//CClassDefNode[@scope]',
+                                '//CClassDefNode[@scope.has_cyclic_pyobject_attrs = False]')
+cdef class ExtTypeNoGC:
+    """
+    >>> obj = ExtTypeNoGC()
+    >>> obj = ExtTypeNoGC()
+    >>> obj = ExtTypeNoGC()
+    >>> obj = ExtTypeNoGC()
+    >>> obj = ExtTypeNoGC()
+    >>> obj = ExtTypeNoGC()
+    """
+
+
+@cython.test_fail_if_path_exists('//CClassDefNode[@scope.has_cyclic_pyobject_attrs = True]')
+@cython.test_assert_path_exists('//CClassDefNode',
+                                '//CClassDefNode[@scope]',
+                                '//CClassDefNode[@scope.has_cyclic_pyobject_attrs = False]')
+cdef class ExtSubTypeNoGC(ExtTypeNoGC):
+    """
+    >>> obj = ExtSubTypeNoGC()
+    >>> obj = ExtSubTypeNoGC()
+    >>> obj = ExtSubTypeNoGC()
+    >>> obj = ExtSubTypeNoGC()
+    >>> obj = ExtSubTypeNoGC()
+    >>> obj = ExtSubTypeNoGC()
+    """
+
+
+@cython.test_fail_if_path_exists('//CClassDefNode[@scope.has_cyclic_pyobject_attrs = True]')
+@cython.test_assert_path_exists('//CClassDefNode',
+                                '//CClassDefNode[@scope]',
+                                '//CClassDefNode[@scope.has_cyclic_pyobject_attrs = False]')
+cdef class ExtTypePyArgsNoGC:
+    """
+    >>> obj = ExtTypePyArgsNoGC()
+    >>> obj = ExtTypePyArgsNoGC()
+    >>> obj = ExtTypePyArgsNoGC()
+    >>> obj = ExtTypePyArgsNoGC()
+    >>> obj = ExtTypePyArgsNoGC()
+    >>> obj = ExtTypePyArgsNoGC()
+    """
+    cdef bytes b
+    cdef str s
+    cdef unicode u
+
+
+@cython.test_fail_if_path_exists('//CClassDefNode[@scope.has_cyclic_pyobject_attrs = True]')
+@cython.test_assert_path_exists('//CClassDefNode',
+                                '//CClassDefNode[@scope]',
+                                '//CClassDefNode[@scope.has_cyclic_pyobject_attrs = False]')
+cdef class ExtSubTypePyArgsNoGC(ExtTypePyArgsNoGC):
+    """
+    >>> obj = ExtSubTypePyArgsNoGC()
+    >>> obj = ExtSubTypePyArgsNoGC()
+    >>> obj = ExtSubTypePyArgsNoGC()
+    >>> obj = ExtSubTypePyArgsNoGC()
+    >>> obj = ExtSubTypePyArgsNoGC()
+    >>> obj = ExtSubTypePyArgsNoGC()
+    """
+
+
+@cython.test_fail_if_path_exists('//CClassDefNode[@scope.has_cyclic_pyobject_attrs = False]')
+@cython.test_assert_path_exists('//CClassDefNode',
+                                '//CClassDefNode[@scope]',
+                                '//CClassDefNode[@scope.has_cyclic_pyobject_attrs = True]')
+cdef class ExtTypePyArgsWithGC:
+    """
+    >>> obj = ExtTypePyArgsWithGC()
+    >>> obj = ExtTypePyArgsWithGC()
+    >>> obj = ExtTypePyArgsWithGC()
+    >>> obj = ExtTypePyArgsWithGC()
+    >>> obj = ExtTypePyArgsWithGC()
+    >>> obj = ExtTypePyArgsWithGC()
+    """
+    cdef bytes b
+    cdef str s
+    cdef unicode u
+    cdef list l
+
+
+@cython.test_fail_if_path_exists('//CClassDefNode[@scope.has_cyclic_pyobject_attrs = True]')
+@cython.test_assert_path_exists('//CClassDefNode',
+                                '//CClassDefNode[@scope]',
+                                '//CClassDefNode[@scope.has_cyclic_pyobject_attrs = False]')
+cdef class ExtSubTypePyArgsWithGC(ExtTypePyArgsWithGC):
+    """
+    >>> obj = ExtSubTypePyArgsWithGC()
+    >>> obj = ExtSubTypePyArgsWithGC()
+    >>> obj = ExtSubTypePyArgsWithGC()
+    >>> obj = ExtSubTypePyArgsWithGC()
+    >>> obj = ExtSubTypePyArgsWithGC()
+    >>> obj = ExtSubTypePyArgsWithGC()
+    """