From 8d6d6c864442a1cc987b3e6bcb1d903ceb975e4a Mon Sep 17 00:00:00 2001
From: Iain Sandoe <iain@sandoe.co.uk>
Date: Mon, 26 Aug 2024 14:09:40 +0100
Subject: c++, coroutines: The frame pointer is used in the helpers [PR116482].

We have a bogus warning about the coroutine state frame pointers
being apparently unused in the resume and destroy functions.  Fixed
by making the parameters DECL_ARTIFICIAL.

	PR c++/116482

gcc/cp/ChangeLog:

	* coroutines.cc
	(coro_build_actor_or_destroy_function): Make the parameter
	decls DECL_ARTIFICIAL.

gcc/testsuite/ChangeLog:

	* g++.dg/coroutines/pr116482.C: New test.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
---
 gcc/cp/coroutines.cc                       |  1 +
 gcc/testsuite/g++.dg/coroutines/pr116482.C | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/coroutines/pr116482.C

(limited to 'gcc')

diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 5bfd794..31dc39a 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -4065,6 +4065,7 @@ coro_build_actor_or_destroy_function (tree orig, tree fn_type,
 
   tree id = get_identifier ("frame_ptr");
   tree fp = build_lang_decl (PARM_DECL, id, coro_frame_ptr);
+  DECL_ARTIFICIAL (fp) = true;
   DECL_CONTEXT (fp) = fn;
   DECL_ARG_TYPE (fp) = type_passed_as (coro_frame_ptr);
   DECL_ARGUMENTS (fn) = fp;
diff --git a/gcc/testsuite/g++.dg/coroutines/pr116482.C b/gcc/testsuite/g++.dg/coroutines/pr116482.C
new file mode 100644
index 0000000..702d1e2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr116482.C
@@ -0,0 +1,30 @@
+// Override default options.
+// { dg-options "-std=c++20 -fno-exceptions -Wall -Wextra" }
+
+#include <coroutine>
+
+struct SuspendNever {
+    bool await_ready();
+    void await_suspend(std::coroutine_handle<>);
+    void await_resume();
+};
+
+struct Coroutine;
+
+struct PromiseType {
+    Coroutine get_return_object();
+    SuspendNever initial_suspend();
+    SuspendNever final_suspend();
+#if __cpp_exceptions
+    void unhandled_exception() { /*std::terminate();*/ };
+#endif
+    void return_void();
+};
+
+struct Coroutine {
+    using promise_type = PromiseType;
+};
+
+Coroutine __async_test_input_basic() {
+    co_return;
+}
-- 
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