Tested on x86_64-darwin/linux, powerpc64le linux, OK for trunk?
thanks,
Iain

--- >8 ---

Awaiters always need to have a coroutine state frame copy since
they persist across potential supensions.  It simplifies the later
analysis considerably to assign these early which we do when
building co_await expressions.

The cleanups in r15-3146-g47dbd69b1, unfortunately elided some of
processing used to cater for cases where the var created from an
xvalue, or is a pointer/reference type.

Corrected thus.

        PR c++/116506

gcc/cp/ChangeLog:

        * coroutines.cc (build_co_await): Ensure that xvalues are
        materialised.  Handle references/pointer values in awaiter
        access expressions.

gcc/testsuite/ChangeLog:

        * g++.dg/coroutines/pr116506.C: New test.

Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
---
 gcc/cp/coroutines.cc                       | 39 ++++++++++------
 gcc/testsuite/g++.dg/coroutines/pr116506.C | 53 ++++++++++++++++++++++
 2 files changed, 77 insertions(+), 15 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/coroutines/pr116506.C

diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index d4d74838eb4..d208ce429db 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -1130,13 +1130,12 @@ build_co_await (location_t loc, tree a, 
suspend_point_kind suspend_kind,
   if (o_type && !VOID_TYPE_P (o_type))
     o_type = complete_type_or_else (o_type, o);
 
-  if (!o_type)
+  if (!o_type || o_type == error_mark_node)
     return error_mark_node;
 
   if (TREE_CODE (o_type) != RECORD_TYPE)
     {
-      error_at (loc, "awaitable type %qT is not a structure",
-               o_type);
+      error_at (loc, "awaitable type %qT is not a structure", o_type);
       return error_mark_node;
     }
 
@@ -1162,20 +1161,32 @@ build_co_await (location_t loc, tree a, 
suspend_point_kind suspend_kind,
   if (!glvalue_p (o))
     o = get_target_expr (o, tf_warning_or_error);
 
-  tree e_proxy = o;
-  if (glvalue_p (o))
+  /* We know that we need a coroutine state frame variable for the awaiter,
+     since it must persist across suspension; so where one is needed, build
+     it now.  */
+  if (INDIRECT_REF_P (o))
+    o = TREE_OPERAND (o, 0);
+  tree e_proxy = STRIP_NOPS (o);
+  o_type = TREE_TYPE (e_proxy);
+  if (lvalue_p (e_proxy))
     o = NULL_TREE; /* Use the existing entity.  */
-  else /* We need to materialise it.  */
+  else /* We need a non-temp var.  */
     {
       e_proxy = get_awaitable_var (suspend_kind, o_type);
       o = cp_build_init_expr (loc, e_proxy, o);
-      e_proxy = convert_from_reference (e_proxy);
     }
 
+  /* Build an expression for the object that will be used to call the awaitable
+     methods.  */
+  tree e_object = convert_from_reference (e_proxy);
+  if (POINTER_TYPE_P (TREE_TYPE (e_object)))
+    e_object = cp_build_indirect_ref (input_location, e_object, RO_UNARY_STAR,
+                                     tf_warning_or_error);
+
   /* I suppose we could check that this is contextually convertible to bool.  
*/
   tree awrd_func = NULL_TREE;
   tree awrd_call
-    = build_new_method_call (e_proxy, awrd_meth, NULL, NULL_TREE, 
LOOKUP_NORMAL,
+    = build_new_method_call (e_object, awrd_meth, NULL, NULL_TREE, 
LOOKUP_NORMAL,
                             &awrd_func, tf_warning_or_error);
 
   if (!awrd_func || !awrd_call || awrd_call == error_mark_node)
@@ -1189,7 +1200,7 @@ build_co_await (location_t loc, tree a, 
suspend_point_kind suspend_kind,
   tree h_proxy = get_coroutine_self_handle_proxy (current_function_decl);
   vec<tree, va_gc> *args = make_tree_vector_single (h_proxy);
   tree awsp_call
-    = build_new_method_call (e_proxy, awsp_meth, &args, NULL_TREE,
+    = build_new_method_call (e_object, awsp_meth, &args, NULL_TREE,
                             LOOKUP_NORMAL, &awsp_func, tf_warning_or_error);
 
   release_tree_vector (args);
@@ -1221,7 +1232,7 @@ build_co_await (location_t loc, tree a, 
suspend_point_kind suspend_kind,
   /* Finally, the type of e.await_resume() is the co_await's type.  */
   tree awrs_func = NULL_TREE;
   tree awrs_call
-    = build_new_method_call (e_proxy, awrs_meth, NULL, NULL_TREE, 
LOOKUP_NORMAL,
+    = build_new_method_call (e_object, awrs_meth, NULL, NULL_TREE, 
LOOKUP_NORMAL,
                             &awrs_func, tf_warning_or_error);
 
   if (!awrs_func || !awrs_call || awrs_call == error_mark_node)
@@ -1235,7 +1246,7 @@ build_co_await (location_t loc, tree a, 
suspend_point_kind suspend_kind,
        return error_mark_node;
       if (coro_diagnose_throwing_fn (awrs_func))
        return error_mark_node;
-      if (tree dummy = cxx_maybe_build_cleanup (e_proxy, tf_none))
+      if (tree dummy = cxx_maybe_build_cleanup (e_object, tf_none))
        {
          if (CONVERT_EXPR_P (dummy))
            dummy = TREE_OPERAND (dummy, 0);
@@ -1246,7 +1257,8 @@ build_co_await (location_t loc, tree a, 
suspend_point_kind suspend_kind,
     }
 
   /* We now have three call expressions, in terms of the promise, handle and
-     'e' proxies.  Save them in the await expression for later expansion.  */
+     'e' proxy expression.  Save them in the await expression for later
+     expansion.  */
 
   tree awaiter_calls = make_tree_vec (3);
   TREE_VEC_ELT (awaiter_calls, 0) = awrd_call; /* await_ready().  */
@@ -1259,9 +1271,6 @@ build_co_await (location_t loc, tree a, 
suspend_point_kind suspend_kind,
     }
   TREE_VEC_ELT (awaiter_calls, 2) = awrs_call; /* await_resume().  */
 
-  if (REFERENCE_REF_P (e_proxy))
-    e_proxy = TREE_OPERAND (e_proxy, 0);
-
   tree awrs_type = TREE_TYPE (TREE_TYPE (awrs_func));
   tree suspend_kind_cst = build_int_cst (integer_type_node,
                                         (int) suspend_kind);
diff --git a/gcc/testsuite/g++.dg/coroutines/pr116506.C 
b/gcc/testsuite/g++.dg/coroutines/pr116506.C
new file mode 100644
index 00000000000..57a6e360566
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr116506.C
@@ -0,0 +1,53 @@
+// { dg-do run }
+// { dg-additional-options "-fno-exceptions" }
+                                                       
+#include <coroutine>
+
+bool g_too_early = true;
+std::coroutine_handle<> g_handle;
+
+struct Awaiter {
+    Awaiter() {}
+    ~Awaiter() {
+        if (g_too_early) {
+            __builtin_abort ();
+        }
+    }
+
+    bool await_ready() { return false; }
+    void await_suspend(std::coroutine_handle<> handle) {
+        g_handle = handle;
+    }
+
+    void await_resume() {}
+};
+
+struct SuspendNever {
+    bool await_ready() noexcept { return true; }
+    void await_suspend(std::coroutine_handle<>) noexcept {}
+    void await_resume() noexcept {}
+};
+
+struct Coroutine {
+    struct promise_type {
+        Coroutine get_return_object() { return {}; }
+        SuspendNever initial_suspend() { return {}; }
+        SuspendNever final_suspend() noexcept { return {}; }
+        void return_void() {}
+        void unhandled_exception() {}
+
+        Awaiter&& await_transform(Awaiter&& u) {
+            return static_cast<Awaiter&&>(u);
+        }
+    };
+};
+
+Coroutine foo() {
+    co_await Awaiter{};
+}
+
+int main() {
+    foo();
+    g_too_early = false;
+    g_handle.destroy();
+}
-- 
2.39.2 (Apple Git-143)

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