bpo-33363: raise SyntaxError for async for/with outside async functions (#6616)

Author: zsol

Lib/test/test_coroutines.py

@@ -362,7 +362,22 @@ async def bar(): pass
             """def foo():
                    async def bar():
                         pass\nawait a
-            """]
+            """,
+            """def foo():
+                   async for i in arange(2):
+                       pass
+            """,
+            """def foo():
+                   async with resource:
+                       pass
+            """,
+            """async with resource:
+                   pass
+            """,
+            """async for i in arange(2):
+                   pass
+            """,
+            ]
 
         for code in samples:
             with self.subTest(code=code), self.assertRaises(SyntaxError):

Misc/NEWS.d/next/Core and Builtins/2018-04-26-22-48-28.bpo-33363.8RCnN2.rst

@@ -0,0 +1,2 @@
+Raise a SyntaxError for ``async with`` and ``async for`` statements outside
+of async functions.

Python/compile.c

@@ -2447,6 +2447,10 @@ static int
 compiler_async_for(struct compiler *c, stmt_ty s)
 {
     basicblock *start, *except, *end;
+    if (c->u->u_scope_type != COMPILER_SCOPE_ASYNC_FUNCTION) {
+        return compiler_error(c, "'async for' outside async function");
+    }
+
     start = compiler_new_block(c);
     except = compiler_new_block(c);
     end = compiler_new_block(c);
@@ -4262,6 +4266,9 @@ compiler_async_with(struct compiler *c, stmt_ty s, int pos)
     withitem_ty item = asdl_seq_GET(s->v.AsyncWith.items, pos);
 
     assert(s->kind == AsyncWith_kind);
+    if (c->u->u_scope_type != COMPILER_SCOPE_ASYNC_FUNCTION) {
+        return compiler_error(c, "'async with' outside async function");
+    }
 
     block = compiler_new_block(c);
     finally = compiler_new_block(c);