coroutines: Add a test for non-trivial await_resume return type (NFC).

[Iain Sandoe]

Hi

Just an improvement to test coverage.

Tested on x86_64 darwin and linux,
applied to master
thanks
Iain
    
gcc/testsuite/ChangeLog:
    
2020-02-29  Iain Sandoe  <iain@sandoe.co.uk>
    
	* g++.dg/coroutines/coro1-ret-int-yield-int.h: Add templated
	awaitable.
	* g++.dg/coroutines/torture/co-await-15-return-non-triv.C: New test.

diff --git a/gcc/testsuite/g++.dg/coroutines/coro1-ret-int-yield-int.h b/gcc/testsuite/g++.dg/coroutines/coro1-ret-int-yield-int.h
index abf625869fa..67ac197fee4 100644
--- a/gcc/testsuite/g++.dg/coroutines/coro1-ret-int-yield-int.h
+++ b/gcc/testsuite/g++.dg/coroutines/coro1-ret-int-yield-int.h
@@ -78,6 +78,16 @@ struct coro1 {
     int& await_resume() const noexcept { PRINT ("susp-always-resume-intprt"); return x;}
   };
 
+  template <typename _AwaitType>
+  struct suspend_always_tmpl_awaiter {
+    _AwaitType x;
+    suspend_always_tmpl_awaiter(_AwaitType __x) : x(__x) {}
+    ~suspend_always_tmpl_awaiter() {}
+    bool await_ready() const noexcept { return false; }
+    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("suspend_always_tmpl_awaiter");}
+    _AwaitType await_resume() const noexcept { PRINT ("suspend_always_tmpl_awaiter"); return x;}
+  };
+
   struct promise_type {
 
   promise_type() : vv(-1) {  PRINT ("Created Promise"); }
diff --git a/gcc/testsuite/g++.dg/coroutines/torture/co-await-15-return-non-triv.C b/gcc/testsuite/g++.dg/coroutines/torture/co-await-15-return-non-triv.C
new file mode 100644
index 00000000000..70c974bc56a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/torture/co-await-15-return-non-triv.C
@@ -0,0 +1,51 @@
+//  { dg-do run }
+
+/* Check that we handle await_resume for a non-trivial type.  */
+
+#include "../coro.h"
+
+// boiler-plate for tests of codegen
+#include "../coro1-ret-int-yield-int.h"
+
+coro1
+f ()
+{
+  struct test {
+    int a;
+    ~test () {}
+  };
+  test input{5};
+  test res = co_await coro1::suspend_always_tmpl_awaiter<test>(input);
+  co_return res.a + 10;
+}
+
+int main ()
+{
+  PRINT ("main: create coro1");
+  struct coro1 f_coro = f ();
+
+  if (f_coro.handle.done())
+    {
+      PRINT ("main: we should not be 'done' [1]");
+      abort ();
+    }
+  PRINT ("main: resuming [1] initial suspend");
+  f_coro.handle.resume();
+  PRINT ("main: resuming [2] co_await suspend_always_tmpl_awaiter");
+  f_coro.handle.resume();
+
+  /* we should now have returned with the co_return (15) */
+  if (!f_coro.handle.done())
+    {
+      PRINT ("main: we should be 'done' ");
+      abort ();
+    }
+  int y = f_coro.handle.promise().get_value();
+  if (y != 15)
+    {
+      PRINTF ("main: y is wrong : %d, should be 15\n", y);
+      abort ();
+    }
+  PRINT ("main: done");
+  return 0;
+}