add coroutine behavior for generators

coroutines don't have __next__; they also call themselves coroutines.
This does not change the fact that `async def` methods are generators,
but it does make them behave more like CPython.

Author: kvc0

mpy-cross/mpconfigport.h

@@ -40,6 +40,7 @@
 
 #define MICROPY_FLOAT_IMPL          (MICROPY_FLOAT_IMPL_DOUBLE)
 #define MICROPY_CPYTHON_COMPAT      (1)
+#define MICROPY_PY_ASYNC_AWAIT      (1)
 #define MICROPY_USE_INTERNAL_PRINTF (0)
 
 #define MICROPY_PY_BUILTINS_STR_UNICODE (1)

py/compile.c

@@ -1890,7 +1890,7 @@ STATIC void compile_async_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
         // async def
         compile_funcdef(comp, pns0);
         scope_t *fscope = (scope_t*)pns0->nodes[4];
-        fscope->scope_flags |= MP_SCOPE_FLAG_GENERATOR;
+        fscope->scope_flags |= MP_SCOPE_FLAG_GENERATOR | MP_SCOPE_FLAG_ASYNC;
     } else if (MP_PARSE_NODE_STRUCT_KIND(pns0) == PN_for_stmt) {
         // async for
         compile_async_for_stmt(comp, pns0);

py/emitglue.c

@@ -152,7 +152,7 @@ mp_obj_t mp_make_function_from_raw_code(const mp_raw_code_t *rc, mp_obj_t def_ar
 
     // check for generator functions and if so wrap in generator object
     if ((rc->scope_flags & MP_SCOPE_FLAG_GENERATOR) != 0) {
-        fun = mp_obj_new_gen_wrap(fun);
+        fun = mp_obj_new_gen_wrap(fun, (rc->scope_flags & MP_SCOPE_FLAG_ASYNC) != 0);
     }
 
     return fun;

py/obj.h

@@ -665,7 +665,7 @@ mp_obj_t mp_obj_new_fun_bc(mp_obj_t def_args, mp_obj_t def_kw_args, const byte *
 mp_obj_t mp_obj_new_fun_native(mp_obj_t def_args_in, mp_obj_t def_kw_args, const void *fun_data, const mp_uint_t *const_table);
 mp_obj_t mp_obj_new_fun_viper(size_t n_args, void *fun_data, mp_uint_t type_sig);
 mp_obj_t mp_obj_new_fun_asm(size_t n_args, void *fun_data, mp_uint_t type_sig);
-mp_obj_t mp_obj_new_gen_wrap(mp_obj_t fun);
+mp_obj_t mp_obj_new_gen_wrap(mp_obj_t fun, bool is_coroutine);
 mp_obj_t mp_obj_new_closure(mp_obj_t fun, size_t n_closed, const mp_obj_t *closed);
 mp_obj_t mp_obj_new_tuple(size_t n, const mp_obj_t *items);
 mp_obj_t mp_obj_new_list(size_t n, mp_obj_t *items);

py/objgenerator.c

@@ -42,11 +42,13 @@
 typedef struct _mp_obj_gen_wrap_t {
     mp_obj_base_t base;
     mp_obj_t *fun;
+    bool coroutine_generator;
 } mp_obj_gen_wrap_t;
 
 typedef struct _mp_obj_gen_instance_t {
     mp_obj_base_t base;
     mp_obj_dict_t *globals;
+    bool coroutine_generator;
     mp_code_state_t code_state;
 } mp_obj_gen_instance_t;
 
@@ -64,6 +66,7 @@ STATIC mp_obj_t gen_wrap_call(mp_obj_t self_in, size_t n_args, size_t n_kw, cons
         n_state * sizeof(mp_obj_t) + n_exc_stack * sizeof(mp_exc_stack_t));
     o->base.type = &mp_type_gen_instance;
 
+    o->coroutine_generator = self->coroutine_generator;
     o->globals = self_fun->globals;
     o->code_state.fun_bc = self_fun;
     o->code_state.ip = 0;
@@ -78,10 +81,11 @@ const mp_obj_type_t mp_type_gen_wrap = {
     .unary_op = mp_generic_unary_op,
 };
 
-mp_obj_t mp_obj_new_gen_wrap(mp_obj_t fun) {
+mp_obj_t mp_obj_new_gen_wrap(mp_obj_t fun, bool is_coroutine) {
     mp_obj_gen_wrap_t *o = m_new_obj(mp_obj_gen_wrap_t);
     o->base.type = &mp_type_gen_wrap;
     o->fun = MP_OBJ_TO_PTR(fun);
+    o->coroutine_generator = is_coroutine;
     return MP_OBJ_FROM_PTR(o);
 }
 
@@ -91,7 +95,11 @@ mp_obj_t mp_obj_new_gen_wrap(mp_obj_t fun) {
 STATIC void gen_instance_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
     (void)kind;
     mp_obj_gen_instance_t *self = MP_OBJ_TO_PTR(self_in);
-    mp_printf(print, "<generator object '%q' at %p>", mp_obj_fun_get_name(MP_OBJ_FROM_PTR(self->code_state.fun_bc)), self);
+    if (self->coroutine_generator) {
+        mp_printf(print, "<coroutine object '%q' at %p>", mp_obj_fun_get_name(MP_OBJ_FROM_PTR(self->code_state.fun_bc)), self);
+    } else {
+        mp_printf(print, "<generator object '%q' at %p>", mp_obj_fun_get_name(MP_OBJ_FROM_PTR(self->code_state.fun_bc)), self);
+    }
 }
 
 mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t throw_value, mp_obj_t *ret_val) {
@@ -194,6 +202,10 @@ STATIC mp_obj_t gen_resume_and_raise(mp_obj_t self_in, mp_obj_t send_value, mp_o
 }
 
 STATIC mp_obj_t gen_instance_iternext(mp_obj_t self_in) {
+    mp_obj_gen_instance_t *self = MP_OBJ_TO_PTR(self_in);
+    if (self->coroutine_generator) {
+        mp_raise_TypeError(translate("'coroutine' object is not an iterator"));
+    }
     return gen_resume_and_raise(self_in, mp_const_none, MP_OBJ_NULL);
 }
 

py/runtime0.h

@@ -33,6 +33,7 @@
 #define MP_SCOPE_FLAG_VARKEYWORDS  (0x02)
 #define MP_SCOPE_FLAG_GENERATOR    (0x04)
 #define MP_SCOPE_FLAG_DEFKWARGS    (0x08)
+#define MP_SCOPE_FLAG_ASYNC        (0x10)
 
 // types for native (viper) function signature
 #define MP_NATIVE_TYPE_OBJ  (0x00)

tests/basics/async_coroutine.py

@@ -0,0 +1,13 @@
+async def f():
+    pass
+
+try:
+    f()  # Should not crash
+except Exception as e:
+    print('failed to invoke')
+
+try:
+    next(f())
+    print('This should fail because async def returns a coroutine, and next() is not allowed')
+except Exception as e:
+    print('pass')

tests/basics/async_coroutine.py.exp

@@ -0,0 +1 @@
+pass