Merge pull request #1802 from scoder/_pep525_async_gen

PEP 525: asynchronous generators

.travis.yml

@@ -35,6 +35,7 @@ branches:
     - master
 
 install:
+  - python -c 'import sys; print("Python %s" % (sys.version,))'
   - CFLAGS="-O2 -ggdb -Wall -Wextra $(python -c 'import sys; print("-fno-strict-aliasing" if sys.version_info[0] == 2 else "")')" python setup.py build
 
 before_script: ccache -s

Cython/Compiler/Code.py

@@ -632,8 +632,8 @@ class FunctionState(object):
             label += '_' + name
         return label
 
-    def new_yield_label(self):
-        label = self.new_label('resume_from_yield')
+    def new_yield_label(self, expr_type='yield'):
+        label = self.new_label('resume_from_%s' % expr_type)
         num_and_label = (len(self.yield_labels) + 1, label)
         self.yield_labels.append(num_and_label)
         return num_and_label
@@ -1628,7 +1628,7 @@ class CCodeWriter(object):
     # Functions delegated to function scope
     def new_label(self, name=None):    return self.funcstate.new_label(name)
     def new_error_label(self):         return self.funcstate.new_error_label()
-    def new_yield_label(self):         return self.funcstate.new_yield_label()
+    def new_yield_label(self, *args):  return self.funcstate.new_yield_label(*args)
     def get_loop_labels(self):         return self.funcstate.get_loop_labels()
     def set_loop_labels(self, labels): return self.funcstate.set_loop_labels(labels)
     def new_loop_labels(self):         return self.funcstate.new_loop_labels()

Cython/Compiler/ExprNodes.py

@@ -2700,8 +2700,7 @@ class IteratorNode(ExprNode):
         code.putln("if (unlikely(!%s)) {" % result_name)
         code.putln("PyObject* exc_type = PyErr_Occurred();")
         code.putln("if (exc_type) {")
-        code.putln("if (likely(exc_type == PyExc_StopIteration ||"
-                   " PyErr_GivenExceptionMatches(exc_type, PyExc_StopIteration))) PyErr_Clear();")
+        code.putln("if (likely(__Pyx_PyErr_GivenExceptionMatches(exc_type, PyExc_StopIteration))) PyErr_Clear();")
         code.putln("else %s" % code.error_goto(self.pos))
         code.putln("}")
         code.putln("break;")
@@ -7883,9 +7882,8 @@ class ScopedExprNode(ExprNode):
 
         code.putln('{ /* enter inner scope */')
         py_entries = []
-        for entry in self.expr_scope.var_entries:
+        for _, entry in sorted(item for item in self.expr_scope.entries.items() if item[0]):
             if not entry.in_closure:
-                code.put_var_declaration(entry)
                 if entry.type.is_pyobject and entry.used:
                     py_entries.append(entry)
         if not py_entries:
@@ -7895,14 +7893,14 @@ class ScopedExprNode(ExprNode):
             return
 
         # must free all local Python references at each exit point
-        old_loop_labels = tuple(code.new_loop_labels())
+        old_loop_labels = code.new_loop_labels()
         old_error_label = code.new_error_label()
 
         generate_inner_evaluation_code(code)
 
         # normal (non-error) exit
         for entry in py_entries:
-            code.put_var_decref(entry)
+            code.put_var_xdecref_clear(entry)
 
         # error/loop body exit points
         exit_scope = code.new_label('exit_scope')
@@ -7912,7 +7910,7 @@ class ScopedExprNode(ExprNode):
             if code.label_used(label):
                 code.put_label(label)
                 for entry in py_entries:
-                    code.put_var_decref(entry)
+                    code.put_var_xdecref_clear(entry)
                 code.put_goto(old_label)
         code.put_label(exit_scope)
         code.putln('} /* exit inner scope */')
@@ -9415,10 +9413,11 @@ class YieldExprNode(ExprNode):
     label_num = 0
     is_yield_from = False
     is_await = False
+    in_async_gen = False
     expr_keyword = 'yield'
 
     def analyse_types(self, env):
-        if not self.label_num:
+        if not self.label_num or (self.is_yield_from and self.in_async_gen):
             error(self.pos, "'%s' not supported here" % self.expr_keyword)
         self.is_temp = 1
         if self.arg is not None:
@@ -9449,7 +9448,8 @@ class YieldExprNode(ExprNode):
         Generate the code to return the argument in 'Naming.retval_cname'
         and to continue at the yield label.
         """
-        label_num, label_name = code.new_yield_label()
+        label_num, label_name = code.new_yield_label(
+            self.expr_keyword.replace(' ', '_'))
         code.use_label(label_name)
 
         saved = []
@@ -9469,9 +9469,15 @@ class YieldExprNode(ExprNode):
                                   nogil=not code.funcstate.gil_owned)
         code.put_finish_refcount_context()
 
-        code.putln("/* return from generator, yielding value */")
+        code.putln("/* return from %sgenerator, %sing value */" % (
+            'async ' if self.in_async_gen else '',
+            'await' if self.is_await else 'yield'))
         code.putln("%s->resume_label = %d;" % (
             Naming.generator_cname, label_num))
+        if self.in_async_gen and not self.is_await:
+            # __Pyx__PyAsyncGenValueWrapperNew() steals a reference to the return value
+            code.putln("return __Pyx__PyAsyncGenValueWrapperNew(%s);" % Naming.retval_cname)
+        else:
             code.putln("return %s;" % Naming.retval_cname)
 
         code.put_label(label_name)
@@ -9480,27 +9486,19 @@ class YieldExprNode(ExprNode):
             if type.is_pyobject:
                 code.putln('%s->%s = 0;' % (Naming.cur_scope_cname, save_cname))
                 code.put_xgotref(cname)
-        code.putln(code.error_goto_if_null(Naming.sent_value_cname, self.pos))
+        self.generate_sent_value_handling_code(code, Naming.sent_value_cname)
         if self.result_is_used:
             self.allocate_temp_result(code)
             code.put('%s = %s; ' % (self.result(), Naming.sent_value_cname))
             code.put_incref(self.result(), py_object_type)
 
+    def generate_sent_value_handling_code(self, code, value_cname):
+        code.putln(code.error_goto_if_null(value_cname, self.pos))
 
-class YieldFromExprNode(YieldExprNode):
-    # "yield from GEN" expression
-    is_yield_from = True
-    expr_keyword = 'yield from'
-
-    def coerce_yield_argument(self, env):
-        if not self.arg.type.is_string:
-            # FIXME: support C arrays and C++ iterators?
-            error(self.pos, "yielding from non-Python object not supported")
-        self.arg = self.arg.coerce_to_pyobject(env)
 
+class _YieldDelegationExprNode(YieldExprNode):
     def yield_from_func(self, code):
-        code.globalstate.use_utility_code(UtilityCode.load_cached("GeneratorYieldFrom", "Coroutine.c"))
-        return "__Pyx_Generator_Yield_From"
+        raise NotImplementedError()
 
     def generate_evaluation_code(self, code, source_cname=None, decref_source=False):
         if source_cname is None:
@@ -9536,13 +9534,29 @@ class YieldFromExprNode(YieldExprNode):
     def handle_iteration_exception(self, code):
         code.putln("PyObject* exc_type = PyErr_Occurred();")
         code.putln("if (exc_type) {")
-        code.putln("if (likely(exc_type == PyExc_StopIteration ||"
-                   " PyErr_GivenExceptionMatches(exc_type, PyExc_StopIteration))) PyErr_Clear();")
+        code.putln("if (likely(exc_type == PyExc_StopIteration || (exc_type != PyExc_GeneratorExit &&"
+                   " __Pyx_PyErr_GivenExceptionMatches(exc_type, PyExc_StopIteration)))) PyErr_Clear();")
         code.putln("else %s" % code.error_goto(self.pos))
         code.putln("}")
 
 
-class AwaitExprNode(YieldFromExprNode):
+class YieldFromExprNode(_YieldDelegationExprNode):
+    # "yield from GEN" expression
+    is_yield_from = True
+    expr_keyword = 'yield from'
+
+    def coerce_yield_argument(self, env):
+        if not self.arg.type.is_string:
+            # FIXME: support C arrays and C++ iterators?
+            error(self.pos, "yielding from non-Python object not supported")
+        self.arg = self.arg.coerce_to_pyobject(env)
+
+    def yield_from_func(self, code):
+        code.globalstate.use_utility_code(UtilityCode.load_cached("GeneratorYieldFrom", "Coroutine.c"))
+        return "__Pyx_Generator_Yield_From"
+
+
+class AwaitExprNode(_YieldDelegationExprNode):
     # 'await' expression node
     #
     # arg         ExprNode   the Awaitable value to await
@@ -9561,29 +9575,34 @@ class AwaitExprNode(YieldFromExprNode):
         return "__Pyx_Coroutine_Yield_From"
 
 
-class AIterAwaitExprNode(AwaitExprNode):
-    # 'await' expression node used in async-for loops to support the pre-Py3.5.2 'aiter' protocol
-    def yield_from_func(self, code):
-        code.globalstate.use_utility_code(UtilityCode.load_cached("CoroutineAIterYieldFrom", "Coroutine.c"))
-        return "__Pyx_Coroutine_AIter_Yield_From"
-
-
 class AwaitIterNextExprNode(AwaitExprNode):
     # 'await' expression node as part of 'async for' iteration
     #
     # Breaks out of loop on StopAsyncIteration exception.
 
-    def fetch_iteration_result(self, code):
-        assert code.break_label, "AwaitIterNextExprNode outside of 'async for' loop"
+    def _generate_break(self, code):
         code.globalstate.use_utility_code(UtilityCode.load_cached("StopAsyncIteration", "Coroutine.c"))
         code.putln("PyObject* exc_type = PyErr_Occurred();")
-        code.putln("if (exc_type && likely(exc_type == __Pyx_PyExc_StopAsyncIteration ||"
-                   " PyErr_GivenExceptionMatches(exc_type, __Pyx_PyExc_StopAsyncIteration))) {")
+        code.putln("if (unlikely(exc_type && (exc_type == __Pyx_PyExc_StopAsyncIteration || ("
+                   " exc_type != PyExc_StopIteration && exc_type != PyExc_GeneratorExit &&"
+                   " __Pyx_PyErr_GivenExceptionMatches(exc_type, __Pyx_PyExc_StopAsyncIteration))))) {")
         code.putln("PyErr_Clear();")
         code.putln("break;")
         code.putln("}")
+
+    def fetch_iteration_result(self, code):
+        assert code.break_label, "AwaitIterNextExprNode outside of 'async for' loop"
+        self._generate_break(code)
         super(AwaitIterNextExprNode, self).fetch_iteration_result(code)
 
+    def generate_sent_value_handling_code(self, code, value_cname):
+        assert code.break_label, "AwaitIterNextExprNode outside of 'async for' loop"
+        code.putln("if (unlikely(!%s)) {" % value_cname)
+        self._generate_break(code)
+        # all non-break exceptions are errors, as in parent class
+        code.putln(code.error_goto(self.pos))
+        code.putln("}")
+
 
 class GlobalsExprNode(AtomicExprNode):
     type = dict_type

Cython/Compiler/ModuleNode.py

@@ -717,6 +717,7 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         code.putln('static const char * %s= %s;' % (Naming.cfilenm_cname, Naming.file_c_macro))
         code.putln('static const char *%s;' % Naming.filename_cname)
 
+        env.use_utility_code(UtilityCode.load_cached("FastTypeChecks", "ModuleSetupCode.c"))
         if has_np_pythran(env):
             env.use_utility_code(UtilityCode.load_cached("PythranConversion", "CppSupport.cpp"))
 
@@ -2151,7 +2152,7 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         code.putln("%s = PyUnicode_FromStringAndSize(\"\", 0); %s" % (
             Naming.empty_unicode, code.error_goto_if_null(Naming.empty_unicode, self.pos)))
 
-        for ext_type in ('CyFunction', 'FusedFunction', 'Coroutine', 'Generator', 'StopAsyncIteration'):
+        for ext_type in ('CyFunction', 'FusedFunction', 'Coroutine', 'Generator', 'AsyncGen', 'StopAsyncIteration'):
             code.putln("#ifdef __Pyx_%s_USED" % ext_type)
             code.put_error_if_neg(self.pos, "__pyx_%s_init()" % ext_type)
             code.putln("#endif")

Cython/Compiler/ParseTreeTransforms.pxd

@@ -51,7 +51,10 @@ cdef class AlignFunctionDefinitions(CythonTransform):
 cdef class YieldNodeCollector(TreeVisitor):
     cdef public list yields
     cdef public list returns
+    cdef public list finallys
     cdef public bint has_return_value
+    cdef public bint has_yield
+    cdef public bint has_await
 
 cdef class MarkClosureVisitor(CythonTransform):
     cdef bint needs_closure

Cython/Compiler/ParseTreeTransforms.py

@@ -192,7 +192,7 @@ class PostParse(ScopeTrackingTransform):
         # unpack a lambda expression into the corresponding DefNode
         collector = YieldNodeCollector()
         collector.visitchildren(node.result_expr)
-        if collector.yields or collector.awaits or isinstance(node.result_expr, ExprNodes.YieldExprNode):
+        if collector.has_yield or collector.has_await or isinstance(node.result_expr, ExprNodes.YieldExprNode):
             body = Nodes.ExprStatNode(
                 node.result_expr.pos, expr=node.result_expr)
         else:
@@ -208,11 +208,22 @@ class PostParse(ScopeTrackingTransform):
 
     def visit_GeneratorExpressionNode(self, node):
         # unpack a generator expression into the corresponding DefNode
-        node.def_node = Nodes.DefNode(node.pos, name=node.name,
-                                      doc=None,
-                                      args=[], star_arg=None,
-                                      starstar_arg=None,
-                                      body=node.loop)
+        collector = YieldNodeCollector()
+        collector.visitchildren(node.loop)
+        node.def_node = Nodes.DefNode(
+            node.pos, name=node.name, doc=None,
+            args=[], star_arg=None, starstar_arg=None,
+            body=node.loop, is_async_def=collector.has_await)
+        self.visitchildren(node)
+        return node
+
+    def visit_ComprehensionNode(self, node):
+        # enforce local scope also in Py2 for async generators (seriously, that's a Py3.6 feature...)
+        if not node.has_local_scope:
+            collector = YieldNodeCollector()
+            collector.visitchildren(node.loop)
+            if collector.has_await:
+                node.has_local_scope = True
         self.visitchildren(node)
         return node
 
@@ -2457,19 +2468,23 @@ class YieldNodeCollector(TreeVisitor):
     def __init__(self):
         super(YieldNodeCollector, self).__init__()
         self.yields = []
-        self.awaits = []
         self.returns = []
+        self.finallys = []
         self.has_return_value = False
+        self.has_yield = False
+        self.has_await = False
 
     def visit_Node(self, node):
         self.visitchildren(node)
 
     def visit_YieldExprNode(self, node):
         self.yields.append(node)
+        self.has_yield = True
         self.visitchildren(node)
 
     def visit_AwaitExprNode(self, node):
-        self.awaits.append(node)
+        self.yields.append(node)
+        self.has_await = True
         self.visitchildren(node)
 
     def visit_ReturnStatNode(self, node):
@@ -2478,6 +2493,10 @@ class YieldNodeCollector(TreeVisitor):
             self.has_return_value = True
         self.returns.append(node)
 
+    def visit_TryFinallyStatNode(self, node):
+        self.visitchildren(node)
+        self.finallys.append(node)
+
     def visit_ClassDefNode(self, node):
         pass
 
@@ -2513,24 +2532,28 @@ class MarkClosureVisitor(CythonTransform):
         collector.visitchildren(node)
 
         if node.is_async_def:
-            if collector.yields:
-                error(collector.yields[0].pos, "'yield' not allowed in async coroutines (use 'await')")
-            yields = collector.awaits
-        elif collector.yields:
-            if collector.awaits:
-                error(collector.yields[0].pos, "'await' not allowed in generators (use 'yield')")
-            yields = collector.yields
+            coroutine_type = Nodes.AsyncGenNode if collector.has_yield else Nodes.AsyncDefNode
+            if collector.has_yield:
+                for yield_expr in collector.yields + collector.returns:
+                    yield_expr.in_async_gen = True
+        elif collector.has_await:
+            found = next(y for y in collector.yields if y.is_await)
+            error(found.pos, "'await' not allowed in generators (use 'yield')")
+            return node
+        elif collector.has_yield:
+            coroutine_type = Nodes.GeneratorDefNode
         else:
             return node
 
-        for i, yield_expr in enumerate(yields, 1):
+        for i, yield_expr in enumerate(collector.yields, 1):
             yield_expr.label_num = i
-        for retnode in collector.returns:
+        for retnode in collector.returns + collector.finallys:
             retnode.in_generator = True
 
         gbody = Nodes.GeneratorBodyDefNode(
-            pos=node.pos, name=node.name, body=node.body)
-        coroutine = (Nodes.AsyncDefNode if node.is_async_def else Nodes.GeneratorDefNode)(
+            pos=node.pos, name=node.name, body=node.body,
+            is_async_gen_body=node.is_async_def and collector.has_yield)
+        coroutine = coroutine_type(
             pos=node.pos, name=node.name, args=node.args,
             star_arg=node.star_arg, starstar_arg=node.starstar_arg,
             doc=node.doc, decorators=node.decorators,
@@ -2576,7 +2599,10 @@ class CreateClosureClasses(CythonTransform):
     def find_entries_used_in_closures(self, node):
         from_closure = []
         in_closure = []
-        for name, entry in node.local_scope.entries.items():
+        for scope in node.local_scope.iter_local_scopes():
+            for name, entry in scope.entries.items():
+                if not name:
+                    continue
                 if entry.from_closure:
                     from_closure.append((name, entry))
                 elif entry.in_closure:
@@ -2586,14 +2612,15 @@ class CreateClosureClasses(CythonTransform):
     def create_class_from_scope(self, node, target_module_scope, inner_node=None):
         # move local variables into closure
         if node.is_generator:
-            for entry in node.local_scope.entries.values():
+            for scope in node.local_scope.iter_local_scopes():
+                for entry in scope.entries.values():
                     if not entry.from_closure:
                         entry.in_closure = True
 
         from_closure, in_closure = self.find_entries_used_in_closures(node)
         in_closure.sort()
 
-        # Now from the begining
+        # Now from the beginning
         node.needs_closure = False
         node.needs_outer_scope = False
 
@@ -2645,8 +2672,9 @@ class CreateClosureClasses(CythonTransform):
                                     is_cdef=True)
             node.needs_outer_scope = True
         for name, entry in in_closure:
-            closure_entry = class_scope.declare_var(pos=entry.pos,
-                                    name=entry.name,
+            closure_entry = class_scope.declare_var(
+                pos=entry.pos,
+                name=entry.name if not entry.in_subscope else None,
                 cname=entry.cname,
                 type=entry.type,
                 is_cdef=True)

Cython/Compiler/Parsing.py

@@ -501,7 +501,7 @@ def p_call_parse_args(s, allow_genexp=True):
             break
         s.next()
 
-    if s.sy == 'for':
+    if s.sy in ('for', 'async'):
         if not keyword_args and not last_was_tuple_unpack:
             if len(positional_args) == 1 and len(positional_args[0]) == 1:
                 positional_args = [[p_genexp(s, positional_args[0][0])]]
@@ -1196,7 +1196,7 @@ def p_f_string_expr(s, unicode_value, pos, starting_index, is_raw):
 # list_display  ::=     "[" [listmaker] "]"
 # listmaker     ::=     (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] )
 # comp_iter     ::=     comp_for | comp_if
-# comp_for      ::=     "for" expression_list "in" testlist [comp_iter]
+# comp_for      ::=     ["async"] "for" expression_list "in" testlist [comp_iter]
 # comp_if       ::=     "if" test [comp_iter]
 
 def p_list_maker(s):
@@ -1208,7 +1208,7 @@ def p_list_maker(s):
         return ExprNodes.ListNode(pos, args=[])
 
     expr = p_test_or_starred_expr(s)
-    if s.sy == 'for':
+    if s.sy in ('for', 'async'):
         if expr.is_starred:
             s.error("iterable unpacking cannot be used in comprehension")
         append = ExprNodes.ComprehensionAppendNode(pos, expr=expr)
@@ -1230,7 +1230,7 @@ def p_list_maker(s):
 
 
 def p_comp_iter(s, body):
-    if s.sy == 'for':
+    if s.sy in ('for', 'async'):
         return p_comp_for(s, body)
     elif s.sy == 'if':
         return p_comp_if(s, body)
@@ -1239,11 +1239,17 @@ def p_comp_iter(s, body):
         return body
 
 def p_comp_for(s, body):
-    # s.sy == 'for'
     pos = s.position()
+    # [async] for ...
+    is_async = False
+    if s.sy == 'async':
+        is_async = True
         s.next()
-    kw = p_for_bounds(s, allow_testlist=False)
-    kw.update(else_clause = None, body = p_comp_iter(s, body))
+
+    # s.sy == 'for'
+    s.expect('for')
+    kw = p_for_bounds(s, allow_testlist=False, is_async=is_async)
+    kw.update(else_clause=None, body=p_comp_iter(s, body), is_async=is_async)
     return Nodes.ForStatNode(pos, **kw)
 
 def p_comp_if(s, body):
@@ -1311,7 +1317,7 @@ def p_dict_or_set_maker(s):
         else:
             break
 
-    if s.sy == 'for':
+    if s.sy in ('for', 'async'):
         # dict/set comprehension
         if len(parts) == 1 and isinstance(parts[0], list) and len(parts[0]) == 1:
             item = parts[0][0]
@@ -1441,13 +1447,13 @@ def p_testlist_comp(s):
         s.next()
         exprs = p_test_or_starred_expr_list(s, expr)
         return ExprNodes.TupleNode(pos, args = exprs)
-    elif s.sy == 'for':
+    elif s.sy in ('for', 'async'):
         return p_genexp(s, expr)
     else:
         return expr
 
 def p_genexp(s, expr):
-    # s.sy == 'for'
+    # s.sy == 'async' | 'for'
     loop = p_comp_for(s, Nodes.ExprStatNode(
         expr.pos, expr = ExprNodes.YieldExprNode(expr.pos, arg=expr)))
     return ExprNodes.GeneratorExpressionNode(expr.pos, loop=loop)

Cython/Compiler/Symtab.py

@@ -4,8 +4,9 @@
 
 from __future__ import absolute_import
 
-import copy
 import re
+import copy
+import operator
 
 try:
     import __builtin__ as builtins
@@ -88,6 +89,7 @@ class Entry(object):
     # is_arg           boolean    Is the arg of a method
     # is_local         boolean    Is a local variable
     # in_closure       boolean    Is referenced in an inner scope
+    # in_subscope      boolean    Belongs to a generator expression scope
     # is_readonly      boolean    Can't be assigned to
     # func_cname       string     C func implementing Python func
     # func_modifiers   [string]   C function modifiers ('inline')
@@ -163,6 +165,7 @@ class Entry(object):
     is_local = 0
     in_closure = 0
     from_closure = 0
+    in_subscope = 0
     is_declared_generic = 0
     is_readonly = 0
     pyfunc_cname = None
@@ -299,6 +302,7 @@ class Scope(object):
     is_py_class_scope = 0
     is_c_class_scope = 0
     is_closure_scope = 0
+    is_genexpr_scope = 0
     is_passthrough = 0
     is_cpp_class_scope = 0
     is_property_scope = 0
@@ -308,6 +312,7 @@ class Scope(object):
     in_cinclude = 0
     nogil = 0
     fused_to_specific = None
+    return_type = None
 
     def __init__(self, name, outer_scope, parent_scope):
         # The outer_scope is the next scope in the lookup chain.
@@ -324,6 +329,7 @@ class Scope(object):
             self.qualified_name = EncodedString(name)
             self.scope_prefix = mangled_name
         self.entries = {}
+        self.subscopes = set()
         self.const_entries = []
         self.type_entries = []
         self.sue_entries = []
@@ -341,7 +347,6 @@ class Scope(object):
         self.obj_to_entry = {}
         self.buffer_entries = []
         self.lambda_defs = []
-        self.return_type = None
         self.id_counters = {}
 
     def __deepcopy__(self, memo):
@@ -419,6 +424,12 @@ class Scope(object):
         """ Return the module-level scope containing this scope. """
         return self.outer_scope.builtin_scope()
 
+    def iter_local_scopes(self):
+        yield self
+        if self.subscopes:
+            for scope in sorted(self.subscopes, key=operator.attrgetter('scope_prefix')):
+                yield scope
+
     def declare(self, name, cname, type, pos, visibility, shadow = 0, is_type = 0, create_wrapper = 0):
         # Create new entry, and add to dictionary if
         # name is not None. Reports a warning if already
@@ -1690,7 +1701,8 @@ class LocalScope(Scope):
         return entry
 
     def mangle_closure_cnames(self, outer_scope_cname):
-        for entry in self.entries.values():
+        for scope in self.iter_local_scopes():
+            for entry in scope.entries.values():
                 if entry.from_closure:
                     cname = entry.outer_entry.cname
                     if self.is_passthrough:
@@ -1709,12 +1721,19 @@ class GeneratorExpressionScope(Scope):
     to generators, these can be easily inlined in some cases, so all
     we really need is a scope that holds the loop variable(s).
     """
+    is_genexpr_scope = True
+
     def __init__(self, outer_scope):
         name = outer_scope.global_scope().next_id(Naming.genexpr_id_ref)
         Scope.__init__(self, name, outer_scope, outer_scope)
+        self.var_entries = outer_scope.var_entries  # keep declarations outside
         self.directives = outer_scope.directives
         self.genexp_prefix = "%s%d%s" % (Naming.pyrex_prefix, len(name), name)
 
+        while outer_scope.is_genexpr_scope:
+            outer_scope = outer_scope.outer_scope
+        outer_scope.subscopes.add(self)
+
     def mangle(self, prefix, name):
         return '%s%s' % (self.genexp_prefix, self.parent_scope.mangle(prefix, name))
 
@@ -1730,8 +1749,9 @@ class GeneratorExpressionScope(Scope):
         # this scope must hold its name exclusively
         cname = '%s%s' % (self.genexp_prefix, self.parent_scope.mangle(Naming.var_prefix, name or self.next_id()))
         entry = self.declare(name, cname, type, pos, visibility)
-        entry.is_variable = 1
-        entry.is_local = 1
+        entry.is_variable = True
+        entry.is_local = True
+        entry.in_subscope = True
         self.var_entries.append(entry)
         self.entries[name] = entry
         return entry

Cython/Compiler/TypeInference.py

@@ -250,8 +250,7 @@ class MarkParallelAssignments(EnvTransform):
 
     def visit_YieldExprNode(self, node):
         if self.parallel_block_stack:
-            error(node.pos, "Yield not allowed in parallel sections")
-
+            error(node.pos, "'%s' not allowed in parallel sections" % node.expr_keyword)
         return node
 
     def visit_ReturnStatNode(self, node):

Cython/Utility/Buffer.c

@@ -111,7 +111,7 @@ static int __Pyx_GetBuffer(PyObject *obj, Py_buffer *view, int flags) {
 
     {{for type_ptr, getbuffer, releasebuffer in types}}
       {{if getbuffer}}
-        if (PyObject_TypeCheck(obj, {{type_ptr}})) return {{getbuffer}}(obj, view, flags);
+        if (__Pyx_TypeCheck(obj, {{type_ptr}})) return {{getbuffer}}(obj, view, flags);
       {{endif}}
     {{endfor}}
 
@@ -130,7 +130,7 @@ static void __Pyx_ReleaseBuffer(Py_buffer *view) {
 
     {{for type_ptr, getbuffer, releasebuffer in types}}
       {{if releasebuffer}}
-        if (PyObject_TypeCheck(obj, {{type_ptr}})) { {{releasebuffer}}(obj, view); return; }
+        if (__Pyx_TypeCheck(obj, {{type_ptr}})) { {{releasebuffer}}(obj, view); return; }
       {{endif}}
     {{endfor}}
 

Cython/Utility/CythonFunction.c

@@ -1218,7 +1218,7 @@ static PyObject* __Pyx_Method_ClassMethod(PyObject *method) {
        methoddescr_type = Py_TYPE(meth);
        Py_DECREF(meth);
     }
-    if (PyObject_TypeCheck(method, methoddescr_type)) {
+    if (__Pyx_TypeCheck(method, methoddescr_type)) {
 #endif
         // cdef classes
         PyMethodDescrObject *descr = (PyMethodDescrObject *)method;
@@ -1238,7 +1238,7 @@ static PyObject* __Pyx_Method_ClassMethod(PyObject *method) {
         return PyClassMethod_New(method);
     }
 #ifdef __Pyx_CyFunction_USED
-    else if (PyObject_TypeCheck(method, __pyx_CyFunctionType)) {
+    else if (__Pyx_TypeCheck(method, __pyx_CyFunctionType)) {
         return PyClassMethod_New(method);
     }
 #endif

Cython/Utility/Exceptions.c

@@ -11,7 +11,15 @@
 
 #if CYTHON_FAST_THREAD_STATE
 #define __Pyx_PyThreadState_declare  PyThreadState *$local_tstate_cname;
-#define __Pyx_PyThreadState_assign  $local_tstate_cname = PyThreadState_GET();
+#if PY_VERSION_HEX >= 0x03050000
+  #define __Pyx_PyThreadState_assign  $local_tstate_cname = _PyThreadState_UncheckedGet();
+#elif PY_VERSION_HEX >= 0x03000000
+  #define __Pyx_PyThreadState_assign  $local_tstate_cname = PyThreadState_Get();
+#elif PY_VERSION_HEX >= 0x02070000
+  #define __Pyx_PyThreadState_assign  $local_tstate_cname = _PyThreadState_Current;
+#else
+  #define __Pyx_PyThreadState_assign  $local_tstate_cname = PyThreadState_Get();
+#endif
 #else
 #define __Pyx_PyThreadState_declare
 #define __Pyx_PyThreadState_assign
@@ -31,11 +39,28 @@ static CYTHON_INLINE int __Pyx_PyErr_ExceptionMatchesInState(PyThreadState* tsta
 /////////////// PyErrExceptionMatches ///////////////
 
 #if CYTHON_FAST_THREAD_STATE
+static int __Pyx_PyErr_ExceptionMatchesTuple(PyObject *exc_type, PyObject *tuple) {
+    Py_ssize_t i, n;
+    n = PyTuple_GET_SIZE(tuple);
+#if PY_MAJOR_VERSION >= 3
+    // the tighter subtype checking in Py3 allows faster out-of-order comparison
+    for (i=0; i<n; i++) {
+        if (exc_type == PyTuple_GET_ITEM(tuple, i)) return 1;
+    }
+#endif
+    for (i=0; i<n; i++) {
+        if (__Pyx_PyErr_GivenExceptionMatches(exc_type, PyTuple_GET_ITEM(tuple, i))) return 1;
+    }
+    return 0;
+}
+
 static CYTHON_INLINE int __Pyx_PyErr_ExceptionMatchesInState(PyThreadState* tstate, PyObject* err) {
     PyObject *exc_type = tstate->curexc_type;
     if (exc_type == err) return 1;
     if (unlikely(!exc_type)) return 0;
-    return PyErr_GivenExceptionMatches(exc_type, err);
+    if (unlikely(PyTuple_Check(err)))
+        return __Pyx_PyErr_ExceptionMatchesTuple(exc_type, err);
+    return __Pyx_PyErr_GivenExceptionMatches(exc_type, err);
 }
 #endif
 

Cython/Utility/FunctionArguments.c

@@ -26,7 +26,7 @@ static CYTHON_INLINE int __Pyx_ArgTypeTest(PyObject *obj, PyTypeObject *type, in
         #endif
     }
     else {
-        if (likely(PyObject_TypeCheck(obj, type))) return 1;
+        if (likely(__Pyx_TypeCheck(obj, type))) return 1;
     }
     __Pyx_RaiseArgumentTypeInvalid(name, obj, type);
     return 0;

Cython/Utility/ModuleSetupCode.c

@@ -326,7 +326,6 @@
   #define PySet_CheckExact(obj)        (Py_TYPE(obj) == &PySet_Type)
 #endif
 
-#define __Pyx_TypeCheck(obj, type) PyObject_TypeCheck(obj, (PyTypeObject *)type)
 #define __Pyx_PyException_Check(obj) __Pyx_TypeCheck(obj, PyExc_Exception)
 
 #if PY_MAJOR_VERSION >= 3
@@ -387,15 +386,17 @@
     #define __Pyx_PyAsyncMethodsStruct PyAsyncMethods
     #define __Pyx_PyType_AsAsync(obj) (Py_TYPE(obj)->tp_as_async)
   #else
+    #define __Pyx_PyType_AsAsync(obj) ((__Pyx_PyAsyncMethodsStruct*) (Py_TYPE(obj)->tp_reserved))
+  #endif
+#else
+  #define __Pyx_PyType_AsAsync(obj) NULL
+#endif
+#ifndef __Pyx_PyAsyncMethodsStruct
     typedef struct {
         unaryfunc am_await;
         unaryfunc am_aiter;
         unaryfunc am_anext;
     } __Pyx_PyAsyncMethodsStruct;
-    #define __Pyx_PyType_AsAsync(obj) ((__Pyx_PyAsyncMethodsStruct*) (Py_TYPE(obj)->tp_reserved))
-  #endif
-#else
-  #define __Pyx_PyType_AsAsync(obj) NULL
 #endif
 
 // restrict
@@ -535,6 +536,110 @@ class __Pyx_FakeReference {
 };
 
 
+/////////////// FastTypeChecks.proto ///////////////
+
+#if CYTHON_COMPILING_IN_CPYTHON
+#define __Pyx_TypeCheck(obj, type) __Pyx_IsSubtype(Py_TYPE(obj), (PyTypeObject *)type)
+static CYTHON_INLINE int __Pyx_IsSubtype(PyTypeObject *a, PyTypeObject *b);/*proto*/
+static CYTHON_INLINE int __Pyx_PyErr_GivenExceptionMatches(PyObject *err, PyObject *type);/*proto*/
+static CYTHON_INLINE int __Pyx_PyErr_GivenExceptionMatches2(PyObject *err, PyObject *type1, PyObject *type2);/*proto*/
+#else
+#define __Pyx_TypeCheck(obj, type) PyObject_TypeCheck(obj, (PyTypeObject *)type)
+#define __Pyx_PyErr_GivenExceptionMatches(err, type) PyErr_GivenExceptionMatches(err, type)
+#define __Pyx_PyErr_GivenExceptionMatches2(err, type1, type2) (PyErr_GivenExceptionMatches(err, type1) || PyErr_GivenExceptionMatches(err, type2))
+#endif
+
+/////////////// FastTypeChecks ///////////////
+//@requires: Exceptions.c::PyThreadStateGet
+//@requires: Exceptions.c::PyErrFetchRestore
+
+#if CYTHON_COMPILING_IN_CPYTHON
+static int __Pyx_InBases(PyTypeObject *a, PyTypeObject *b) {
+    while (a) {
+        a = a->tp_base;
+        if (a == b)
+            return 1;
+    }
+    return b == &PyBaseObject_Type;
+}
+
+static CYTHON_INLINE int __Pyx_IsSubtype(PyTypeObject *a, PyTypeObject *b) {
+    PyObject *mro;
+    if (a == b) return 1;
+    mro = a->tp_mro;
+    if (likely(mro)) {
+        Py_ssize_t i, n;
+        n = PyTuple_GET_SIZE(mro);
+        for (i = 0; i < n; i++) {
+            if (PyTuple_GET_ITEM(mro, i) == (PyObject *)b)
+                return 1;
+        }
+        return 0;
+    }
+    // should only get here for incompletely initialised types, i.e. never under normal usage patterns
+    return __Pyx_InBases(a, b);
+}
+
+
+#if PY_MAJOR_VERSION == 2
+static int __Pyx_inner_PyErr_GivenExceptionMatches2(PyObject *err, PyObject* exc_type1, PyObject* exc_type2) {
+    // PyObject_IsSubclass() can recurse and therefore is not safe
+    PyObject *exception, *value, *tb;
+    int res;
+    __Pyx_PyThreadState_declare
+    __Pyx_PyThreadState_assign
+    __Pyx_ErrFetch(&exception, &value, &tb);
+
+    res = exc_type1 ? PyObject_IsSubclass(err, exc_type1) : 0;
+    // This function must not fail, so print the error here (which also clears it)
+    if (unlikely(res == -1)) {
+        PyErr_WriteUnraisable(err);
+        res = 0;
+    }
+    if (!res) {
+        res = PyObject_IsSubclass(err, exc_type2);
+        // This function must not fail, so print the error here (which also clears it)
+        if (unlikely(res == -1)) {
+            PyErr_WriteUnraisable(err);
+            res = 0;
+        }
+    }
+
+    __Pyx_ErrRestore(exception, value, tb);
+    return res;
+}
+#else
+static CYTHON_INLINE int __Pyx_inner_PyErr_GivenExceptionMatches2(PyObject *err, PyObject* exc_type1, PyObject *exc_type2) {
+    int res = exc_type1 ? __Pyx_IsSubtype((PyTypeObject*)err, (PyTypeObject*)exc_type1) : 0;
+    if (!res) {
+        res = __Pyx_IsSubtype((PyTypeObject*)err, (PyTypeObject*)exc_type2);
+    }
+    return res;
+}
+#endif
+
+// so far, we only call PyErr_GivenExceptionMatches() with an exception type (not instance) as first argument
+// => optimise for that case
+
+static CYTHON_INLINE int __Pyx_PyErr_GivenExceptionMatches(PyObject *err, PyObject* exc_type) {
+    if (likely(err == exc_type)) return 1;
+    if (likely(PyExceptionClass_Check(err))) {
+        return __Pyx_inner_PyErr_GivenExceptionMatches2(err, NULL, exc_type);
+    }
+    return PyErr_GivenExceptionMatches(err, exc_type);
+}
+
+static CYTHON_INLINE int __Pyx_PyErr_GivenExceptionMatches2(PyObject *err, PyObject *exc_type1, PyObject *exc_type2) {
+    if (likely(err == exc_type1 || err == exc_type2)) return 1;
+    if (likely(PyExceptionClass_Check(err))) {
+        return __Pyx_inner_PyErr_GivenExceptionMatches2(err, exc_type1, exc_type2);
+    }
+    return (PyErr_GivenExceptionMatches(err, exc_type1) || PyErr_GivenExceptionMatches(err, exc_type2));
+}
+
+#endif
+
+
 /////////////// MathInitCode ///////////////
 
 #if defined(WIN32) || defined(MS_WINDOWS)

Cython/Utility/ObjectHandling.c

@@ -166,8 +166,7 @@ static CYTHON_INLINE PyObject *__Pyx_PyIter_Next2(PyObject* iterator, PyObject*
     if (defval) {
         PyObject* exc_type = PyErr_Occurred();
         if (exc_type) {
-            if (unlikely(exc_type != PyExc_StopIteration) &&
-                    !PyErr_GivenExceptionMatches(exc_type, PyExc_StopIteration))
+            if (unlikely(!__Pyx_PyErr_GivenExceptionMatches(exc_type, PyExc_StopIteration)))
                 return NULL;
             PyErr_Clear();
         }
@@ -194,7 +193,7 @@ static CYTHON_INLINE int __Pyx_IterFinish(void) {
     PyThreadState *tstate = PyThreadState_GET();
     PyObject* exc_type = tstate->curexc_type;
     if (unlikely(exc_type)) {
-        if (likely(exc_type == PyExc_StopIteration) || PyErr_GivenExceptionMatches(exc_type, PyExc_StopIteration)) {
+        if (likely(__Pyx_PyErr_GivenExceptionMatches(exc_type, PyExc_StopIteration))) {
             PyObject *exc_value, *exc_tb;
             exc_value = tstate->curexc_value;
             exc_tb = tstate->curexc_traceback;
@@ -917,7 +916,7 @@ static CYTHON_INLINE int __Pyx_TypeTest(PyObject *obj, PyTypeObject *type) {
         PyErr_SetString(PyExc_SystemError, "Missing type object");
         return 0;
     }
-    if (likely(PyObject_TypeCheck(obj, type)))
+    if (likely(__Pyx_TypeCheck(obj, type)))
         return 1;
     PyErr_Format(PyExc_TypeError, "Cannot convert %.200s to %.200s",
                  Py_TYPE(obj)->tp_name, type->tp_name);
@@ -1123,7 +1122,7 @@ static int __Pyx_TryUnpackUnboundCMethod(__Pyx_CachedCFunction* target) {
 #if CYTHON_COMPILING_IN_CPYTHON
     #if PY_MAJOR_VERSION >= 3
     // method dscriptor type isn't exported in Py2.x, cannot easily check the type there
-    if (likely(PyObject_TypeCheck(method, &PyMethodDescr_Type)))
+    if (likely(__Pyx_TypeCheck(method, &PyMethodDescr_Type)))
     #endif
     {
         PyMethodDescrObject *descr = (PyMethodDescrObject*) method;
@@ -1269,6 +1268,7 @@ bad:
 /////////////// PyObjectCallMethod1.proto ///////////////
 
 static PyObject* __Pyx_PyObject_CallMethod1(PyObject* obj, PyObject* method_name, PyObject* arg); /*proto*/
+static PyObject* __Pyx__PyObject_CallMethod1(PyObject* method, PyObject* arg); /*proto*/
 
 /////////////// PyObjectCallMethod1 ///////////////
 //@requires: PyObjectGetAttrStr
@@ -1276,10 +1276,8 @@ static PyObject* __Pyx_PyObject_CallMethod1(PyObject* obj, PyObject* method_name
 //@requires: PyFunctionFastCall
 //@requires: PyCFunctionFastCall
 
-static PyObject* __Pyx_PyObject_CallMethod1(PyObject* obj, PyObject* method_name, PyObject* arg) {
-    PyObject *method, *result = NULL;
-    method = __Pyx_PyObject_GetAttrStr(obj, method_name);
-    if (unlikely(!method)) goto done;
+static PyObject* __Pyx__PyObject_CallMethod1(PyObject* method, PyObject* arg) {
+    PyObject *result = NULL;
 #if CYTHON_UNPACK_METHODS
     if (likely(PyMethod_Check(method))) {
         PyObject *self = PyMethod_GET_SELF(method);
@@ -1307,7 +1305,6 @@ static PyObject* __Pyx_PyObject_CallMethod1(PyObject* obj, PyObject* method_name
             Py_INCREF(arg);
             PyTuple_SET_ITEM(args, 1, arg);
             Py_INCREF(function);
-            Py_DECREF(method); method = NULL;
             result = __Pyx_PyObject_Call(function, args, NULL);
             Py_DECREF(args);
             Py_DECREF(function);
@@ -1316,6 +1313,15 @@ static PyObject* __Pyx_PyObject_CallMethod1(PyObject* obj, PyObject* method_name
     }
 #endif
     result = __Pyx_PyObject_CallOneArg(method, arg);
+done:
+    return result;
+}
+
+static PyObject* __Pyx_PyObject_CallMethod1(PyObject* obj, PyObject* method_name, PyObject* arg) {
+    PyObject *method, *result = NULL;
+    method = __Pyx_PyObject_GetAttrStr(obj, method_name);
+    if (unlikely(!method)) goto done;
+    result = __Pyx__PyObject_CallMethod1(method, arg);
 done:
     Py_XDECREF(method);
     return result;
@@ -1747,7 +1753,7 @@ static CYTHON_INLINE PyObject* __Pyx_PyObject_CallNoArg(PyObject *func) {
     }
 #endif
 #ifdef __Pyx_CyFunction_USED
-    if (likely(PyCFunction_Check(func) || PyObject_TypeCheck(func, __pyx_CyFunctionType))) {
+    if (likely(PyCFunction_Check(func) || __Pyx_TypeCheck(func, __pyx_CyFunctionType))) {
 #else
     if (likely(PyCFunction_Check(func))) {
 #endif

runtests.py

@@ -1837,6 +1837,9 @@ def main():
     parser.add_option("--exit-ok", dest="exit_ok", default=False,
                       action="store_true",
                       help="exit without error code even on test failures")
+    parser.add_option("--failfast", dest="failfast", default=False,
+                      action="store_true",
+                      help="stop on first failure or error")
     parser.add_option("--root-dir", dest="root_dir", default=os.path.join(DISTDIR, 'tests'),
                       help="working directory")
     parser.add_option("--work-dir", dest="work_dir", default=os.path.join(os.getcwd(), 'TEST_TMP'),
@@ -2137,8 +2140,16 @@ def runtests(options, cmd_args, coverage=None):
             except OSError: pass  # concurrency issue?
         test_runner = XMLTestRunner(output=xml_output_dir,
                                     verbose=options.verbosity > 0)
+        if options.failfast:
+            sys.stderr.write("--failfast not supported with XML runner\n")
+    else:
+        text_runner_options = {}
+        if options.failfast:
+            if sys.version_info < (2, 7):
+                sys.stderr.write("--failfast not supported with Python < 2.7\n")
             else:
-        test_runner = unittest.TextTestRunner(verbosity=options.verbosity)
+                text_runner_options['failfast'] = True
+        test_runner = unittest.TextTestRunner(verbosity=options.verbosity, **text_runner_options)
 
     if options.pyximport_py:
         from pyximport import pyximport

tests/errors/e_cython_parallel.pyx

@@ -168,8 +168,8 @@ e_cython_parallel.pyx:55:9: local variable 'y' referenced before assignment
 e_cython_parallel.pyx:60:6: Reduction operator '*' is inconsistent with previous reduction operator '+'
 e_cython_parallel.pyx:62:36: cython.parallel.parallel() does not take positional arguments
 e_cython_parallel.pyx:65:36: Invalid keyword argument: invalid
-e_cython_parallel.pyx:73:12: Yield not allowed in parallel sections
-e_cython_parallel.pyx:77:16: Yield not allowed in parallel sections
+e_cython_parallel.pyx:73:12: 'yield' not allowed in parallel sections
+e_cython_parallel.pyx:77:16: 'yield' not allowed in parallel sections
 e_cython_parallel.pyx:97:19: Cannot assign to private of outer parallel block
 e_cython_parallel.pyx:98:19: Cannot assign to private of outer parallel block
 e_cython_parallel.pyx:104:6: Reductions not allowed for parallel blocks

tests/errors/pep492_badsyntax_async10.pyx

-# mode: error
-# tag: pep492, async
-
-async def genexpr(it):
-    return (await x for x in it)
-
-
-async def listcomp(it):
-    return [await x for x in it]
-
-
-async def setcomp(it):
-    return {await x for x in it}
-
-
-async def dictcomp(it):
-    return {await x:x+1 for x in it}
-
-
-# NOTE: CPython doesn't allow comprehensions either
-
-
-_ERRORS = """
-5:12: 'await' not allowed in generators (use 'yield')
-5:12: 'await' not supported here
-"""

tests/errors/pep492_badsyntax_async3.pyx

-# mode: error
-# tag: pep492, async
-
-async def foo():
-    [i async for i in els]
-
-_ERRORS = """
-5:7: Expected ']', found 'async'
-"""

tests/errors/pep492_badsyntax_async6.pyx

-# mode: error
-# tag: pep492, async
-
-async def foo():
-    yield
-
-_ERRORS = """
-5:4: 'yield' not allowed in async coroutines (use 'await')
-5:4: 'yield' not supported here
-"""

tests/errors/pep492_badsyntax_async7.pyx

@@ -6,5 +6,4 @@ async def foo():
 
 _ERRORS = """
 5:4: 'yield from' not supported here
-5:4: 'yield' not allowed in async coroutines (use 'await')
 """

tests/run/async_iter_pep492.pyx

@@ -175,7 +175,7 @@ def test_broken_anext():
     >>> testfunc = test_broken_anext()
     >>> try: run_async(testfunc())
     ... except TypeError as exc:
-    ...     assert ' int ' in str(exc)
+    ...     assert ' int' in str(exc)
     ... else:
     ...     print("NOT RAISED!")
     """
@@ -279,9 +279,10 @@ def test_with_for():
     print(I[0])
 
 
-cdef class AI_old:
-    async def __aiter__(self):
-        1/0
+# old-style pre-3.5.2 AIter protocol - no longer supported
+#cdef class AI_old:
+#    async def __aiter__(self):
+#        1/0
 
 
 cdef class AI_new:
@@ -291,9 +292,9 @@ cdef class AI_new:
 
 def test_aiter_raises(AI):
     """
-    >>> test_aiter_raises(AI_old)
-    RAISED
-    0
+    #>>> test_aiter_raises(AI_old)
+    #RAISED
+    #0
     >>> test_aiter_raises(AI_new)
     RAISED
     0

tests/run/cython3.pyx

@@ -329,6 +329,7 @@ def loop_over_unicode_literal():
         assert uchar in 'abcdefg'
     return cython.typeof(uchar)
 
+
 def list_comp():
     """
     >>> list_comp()
@@ -339,6 +340,28 @@ def list_comp():
     assert x == 'abc' # don't leak in Py3 code
     return result
 
+
+def list_comp_iterable(it):
+    """
+    >>> list_comp_iterable([])
+    []
+    >>> list_comp_iterable([0])
+    [0]
+    >>> list_comp_iterable([1])
+    []
+    >>> list_comp_iterable([0, 1])
+    [0]
+    >>> list_comp_iterable([2])
+    [4]
+    >>> list_comp_iterable(range(5))
+    [0, 4, 8]
+    """
+    x = 'abc'
+    result = [x*2 for x in it if x % 2 == 0]
+    assert x == 'abc' # don't leak in Py3 code
+    return result
+
+
 def list_comp_with_lambda():
     """
     >>> list_comp_with_lambda()

tests/run/listcomp.pyx

@@ -97,6 +97,10 @@ def listcomp_as_condition(sequence):
 @cython.test_assert_path_exists("//ComprehensionNode")
 def sorted_listcomp(sequence):
     """
+    >>> sorted_listcomp([])
+    []
+    >>> sorted_listcomp([1])
+    [2]
     >>> sorted_listcomp([3,2,4])
     [3, 4, 5]
     """

tests/run/test_grammar.py

@@ -1177,7 +1177,7 @@ class GrammarTests(unittest.TestCase):
         class Done(Exception): pass
 
         class AIter:
-            async def __aiter__(self):
+            def __aiter__(self):
                 return self
             async def __anext__(self):
                 raise StopAsyncIteration