c++, coroutines: Allow convertible get_return_on_allocation_fail [PR109682].

We have been requiring the get_return_on_allocation_fail() call to have the
same type as the ramp.  This is not intended by the standard, so relax that
to allow anything convertible to the ramp return.

	PR c++/109682

gcc/cp/ChangeLog:

	* coroutines.cc
	(cp_coroutine_transform::build_ramp_function): Allow for cases where
	get_return_on_allocation_fail has a type convertible to the ramp
	return type.

gcc/testsuite/ChangeLog:

	* g++.dg/coroutines/pr109682.C: New test.

Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>

2 files changed, 34 insertions, 13 deletions

diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index e46b8b6..1a6e191 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -4761,25 +4761,18 @@ cp_coroutine_transform::build_ramp_function ()
 	 control to the caller of the coroutine and the return value is
 	 obtained by a call to T::get_return_object_on_allocation_failure(),
 	 where T is the promise type.  */
-
-      gcc_checking_assert (same_type_p (fn_return_type, TREE_TYPE (grooaf)));
       tree if_stmt = begin_if_stmt ();
       tree cond = build1 (CONVERT_EXPR, frame_ptr_type, nullptr_node);
       cond = build2 (EQ_EXPR, boolean_type_node, coro_fp, cond);
       finish_if_stmt_cond (cond, if_stmt);
+      r = NULL_TREE;
       if (void_ramp_p)
-	{
-	  /* Execute the get-return-object-on-alloc-fail call...  */
-	  finish_expr_stmt (grooaf);
-	  /* ... but discard the result, since we return void.  */
-	  finish_return_stmt (NULL_TREE);
-	}
+	/* Execute the get-return-object-on-alloc-fail call...  */
+	finish_expr_stmt (grooaf);
       else
-	{
-	  /* Get the fallback return object.  */
-	  r = build_cplus_new (fn_return_type, grooaf, tf_warning_or_error);
-	  finish_return_stmt (r);
-	}
+	/* Get the fallback return object.  */
+	r = grooaf;
+      finish_return_stmt (r);
       finish_then_clause (if_stmt);
       finish_if_stmt (if_stmt);
     }
diff --git a/gcc/testsuite/g++.dg/coroutines/pr109682.C b/gcc/testsuite/g++.dg/coroutines/pr109682.C
new file mode 100644
index 0000000..24aab92
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr109682.C
@@ -0,0 +1,28 @@
+
+#include <coroutine>
+#include <new>
+
+struct test
+{
+  test () {}
+  test (int) {}
+
+  struct promise_type {
+    test get_return_object () { return {}; }
+    //     vvv
+    static int get_return_object_on_allocation_failure () { return {}; }
+    std::suspend_never initial_suspend () noexcept { return {}; }
+    std::suspend_never final_suspend () noexcept { return {}; }
+    void return_void () {}
+    void unhandled_exception () {}
+  };
+};
+
+test
+f () { co_return; }
+
+int
+main ()
+{
+  f ();
+}