The revised wording for coroutines, uses decltype(auto) for the
type of the get return object, which preserves references. The
test is expected to fail, since it attempts to initialize the
return object from an object that has already been destroyed.
gcc/cp/ChangeLog:
* coroutines.cc
(cp_coroutine_transform::build_ramp_function): Use
decltype(auto) to determine the type of the temporary
get_return_object.
gcc/testsuite/ChangeLog:
* g++.dg/coroutines/pr115908.C: Count promise construction
and destruction.
Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
---
gcc/cp/coroutines.cc | 22 ++++---
gcc/testsuite/g++.dg/coroutines/pr115908.C | 69 +++++++++++++++-------
2 files changed, 60 insertions(+), 31 deletions(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 42f6e32e89c..ce3e022a516 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -5120,8 +5120,11 @@ cp_coroutine_transform::build_ramp_function ()
/* Check for a bad get return object type.
[dcl.fct.def.coroutine] / 7 requires:
The expression promise.get_return_object() is used to initialize the
- returned reference or prvalue result object ... */
- tree gro_type = TREE_TYPE (get_ro);
+ returned reference or prvalue result object ...
+ When we use a local to hold this, it is decltype(auto). */
+ tree gro_type
+ = finish_decltype_type (get_ro, /*id_expression_or_member_access_p*/true,
+ tf_warning_or_error); // TREE_TYPE (get_ro);
if (VOID_TYPE_P (gro_type) && !void_ramp_p)
{
error_at (fn_start, "no viable conversion from %<void%> provided by"
@@ -5129,11 +5132,6 @@ cp_coroutine_transform::build_ramp_function ()
return false;
}
- /* Initialize the resume_idx_var to 0, meaning "not started". */
- coro_build_and_push_artificial_var_with_dve
- (loc, coro_resume_index_id, short_unsigned_type_node, orig_fn_decl,
- build_zero_cst (short_unsigned_type_node), deref_fp);
-
/* [dcl.fct.def.coroutine] / 7
The expression promise.get_return_object() is used to initialize the
glvalue result or prvalue result object of a call to a coroutine. */
@@ -5153,7 +5151,7 @@ cp_coroutine_transform::build_ramp_function ()
= coro_build_and_push_artificial_var (loc, "_Coro_gro", gro_type,
orig_fn_decl, NULL_TREE);
- r = cp_build_init_expr (coro_gro, get_ro);
+ r = cp_build_init_expr (coro_gro, STRIP_REFERENCE_REF (get_ro));
finish_expr_stmt (r);
tree coro_gro_cleanup
= cxx_maybe_build_cleanup (coro_gro, tf_warning_or_error);
@@ -5161,6 +5159,11 @@ cp_coroutine_transform::build_ramp_function ()
push_cleanup (coro_gro, coro_gro_cleanup, /*eh_only*/false);
}
+ /* Initialize the resume_idx_var to 0, meaning "not started". */
+ coro_build_and_push_artificial_var_with_dve
+ (loc, coro_resume_index_id, short_unsigned_type_node, orig_fn_decl,
+ build_zero_cst (short_unsigned_type_node), deref_fp);
+
/* Start the coroutine body. */
r = build_call_expr_loc (fn_start, resumer, 1, coro_fp);
finish_expr_stmt (r);
@@ -5179,7 +5182,8 @@ cp_coroutine_transform::build_ramp_function ()
/* The ramp is done, we just need the return statement, which we build from
the return object we constructed before we called the function body. */
- finish_return_stmt (void_ramp_p ? NULL_TREE : coro_gro);
+ r = void_ramp_p ? NULL_TREE : convert_from_reference (coro_gro);
+ finish_return_stmt (r);
if (flag_exceptions)
{
diff --git a/gcc/testsuite/g++.dg/coroutines/pr115908.C
b/gcc/testsuite/g++.dg/coroutines/pr115908.C
index ac27d916de2..6956c83a8df 100644
--- a/gcc/testsuite/g++.dg/coroutines/pr115908.C
+++ b/gcc/testsuite/g++.dg/coroutines/pr115908.C
@@ -6,23 +6,28 @@
struct Promise;
-bool promise_live = false;
+int promise_life = 0;
struct Handle : std::coroutine_handle<Promise> {
+
+#if 1
+ /* We now expect the handle to be created after the promise is destroyed.
*/
Handle(Promise &p) :
std::coroutine_handle<Promise>(Handle::from_promise(p)) {
- if (!promise_live)
- __builtin_abort ();
#ifdef OUTPUT
- std::cout << "Handle(Promise &)\n";
+ std::cout << "Handle(Promise &) " << promise_life << std::endl;
#endif
- }
- Handle(Promise &&p) :
std::coroutine_handle<Promise>(Handle::from_promise(p)) {
- if (!promise_live)
+ if (promise_life <= 0)
__builtin_abort ();
+ }
+#endif
+
+ Handle(Promise &&p) :
std::coroutine_handle<Promise>(Handle::from_promise(p)) {
#ifdef OUTPUT
- std::cout << "Handle(Promise &&)\n";
+ std::cout << "Handle(Promise &&) " << promise_life << std::endl;
#endif
- }
+ if (promise_life <= 0)
+ __builtin_abort ();
+ }
using promise_type = Promise;
};
@@ -30,46 +35,66 @@ struct Handle : std::coroutine_handle<Promise> {
struct Promise {
Promise() {
#ifdef OUTPUT
- std::cout << "Promise()\n";
+ std::cout << "Promise()" << std::endl;
#endif
- promise_live = true;
+ promise_life++;
}
+
~Promise() {
#ifdef OUTPUT
- std::cout << "~Promise()\n";
+ std::cout << "~Promise()" << std::endl;
#endif
- if (!promise_live)
+ if (promise_life <= 0)
__builtin_abort ();
- promise_live = false;
+ promise_life--;
}
+
Promise& get_return_object() noexcept {
#ifdef OUTPUT
- std::cout << "get_return_object()\n";
+ std::cout << "get_return_object() " << promise_life << std::endl;
#endif
- if (!promise_live)
+ if (promise_life <= 0)
__builtin_abort ();
return *this;
}
- std::suspend_never initial_suspend() const noexcept { return {}; }
- std::suspend_never final_suspend() const noexcept { return {}; }
+
+ std::suspend_never initial_suspend() const noexcept {
+#ifdef OUTPUT
+ std::cout << "initial_suspend()" << std::endl;
+#endif
+ return {};
+ }
+ std::suspend_never final_suspend() const noexcept {
+#ifdef OUTPUT
+ std::cout << "final_suspend()" << std::endl;
+#endif
+ return {};
+ }
void return_void() const noexcept {
- if (!promise_live)
+ if (!promise_life)
__builtin_abort ();
#ifdef OUTPUT
- std::cout << "return_void()\n";
+ std::cout << "return_void()" << std::endl;
#endif
}
void unhandled_exception() const noexcept {}
};
Handle Coro() {
+
+#ifdef OUTPUT
+ std::cout << "Coro()" << std::endl;
+#endif
co_return;
}
int main() {
- Coro();
- if (promise_live)
+ Coro();
+#ifdef OUTPUT
+ std::cout << "done Coro()" << std::endl;
+#endif
+ if (promise_life)
__builtin_abort ();
return 0;
}
--
2.39.2 (Apple Git-143)
