Build coroutine expression with unknown_type in processing_template_decl phase.

gcc/cp
        * coroutines.cc (finish_co_await_expr): Build co_await_expr
        with unknown_type_node.
        (finish_co_yield_expr): Ditto.
        *pt.c (type_dependent_expression_p): Set co_await/yield_expr
        with unknown type as dependent.

gcc/testsuite
        * g++.dg/coroutines/torture/co-await-14-template-traits.C: New test.

gcc/cp/ChangeLog

+2020-03-03  Jun Ma <JunMa@linux.alibaba.com>
+
+	* coroutines.cc (finish_co_await_expr): Build co_await_expr
+	with unknown_type_node.
+	(finish_co_yield_expr): Ditto.
+	*pt.c (type_dependent_expression_p): Set co_await/yield_expr
+	with unknown type as dependent.
+
 2020-03-02  Iain Sandoe  <iain@sandoe.co.uk>
 
 	* coroutines.cc (struct local_var_info): Adjust to remove the

gcc/cp/coroutines.cc

@@ -847,8 +847,8 @@ finish_co_await_expr (location_t kw, tree expr)
       /* If we don't know the promise type, we can't proceed.  */
       tree functype = TREE_TYPE (current_function_decl);
       if (dependent_type_p (functype) || type_dependent_expression_p (expr))
-	return build5_loc (kw, CO_AWAIT_EXPR, TREE_TYPE (expr), expr, NULL_TREE,
-			   NULL_TREE, NULL_TREE, integer_zero_node);
+	return build5_loc (kw, CO_AWAIT_EXPR, unknown_type_node, expr,
+			   NULL_TREE, NULL_TREE, NULL_TREE, integer_zero_node);
     }
 
   /* We must be able to look up the "await_transform" method in the scope of
@@ -925,7 +925,7 @@ finish_co_yield_expr (location_t kw, tree expr)
       tree functype = TREE_TYPE (current_function_decl);
       /* If we don't know the promise type, we can't proceed.  */
       if (dependent_type_p (functype) || type_dependent_expression_p (expr))
-	return build2_loc (kw, CO_YIELD_EXPR, TREE_TYPE (expr), expr,
+	return build2_loc (kw, CO_YIELD_EXPR, unknown_type_node, expr,
 			   NULL_TREE);
     }
 

gcc/cp/pt.c

@@ -26701,6 +26701,11 @@ type_dependent_expression_p (tree expression)
       if (TREE_CODE (expression) == SCOPE_REF)
 	return false;
 
+      /* CO_AWAIT/YIELD_EXPR with unknown type is always dependent.  */
+      if (TREE_CODE (expression) == CO_AWAIT_EXPR
+	  || TREE_CODE (expression) == CO_YIELD_EXPR)
+	return true;
+
       if (BASELINK_P (expression))
 	{
 	  if (BASELINK_OPTYPE (expression)

gcc/testsuite/ChangeLog

+2020-03-03  Jun Ma <JunMa@linux.alibaba.com>
+
+	* g++.dg/coroutines/torture/co-await-14-template-traits.C: New test.
+
 2020-03-02  David Malcolm  <dmalcolm@redhat.com>
 
 	* gcc.dg/analyzer/CVE-2005-1689-dedupe-issue.c: Add

gcc/testsuite/g++.dg/coroutines/torture/co-await-14-template-traits.C

+//  { dg-do compile }
+//  Test we create co_await_expr with dependent type rather than type of awaitable class
+
+#include "../coro.h"
+#include "../coro1-ret-int-yield-int.h"
+#include <chrono>
+
+struct TestAwaiter {
+    int recent_test;
+    TestAwaiter(int test) : recent_test{test} {}
+    bool await_ready() { return true; }
+    void await_suspend(coro::coroutine_handle<>) {}
+    int await_resume() { return recent_test;}
+    void return_value(int x) { recent_test = x;}
+};
+
+template <typename Rep, typename Period>
+coro1 test_temparg (std::chrono::duration<Rep, Period> dur)
+{
+       auto sum = co_await TestAwaiter(1);
+       if (!sum)
+	 dur.count();
+       co_return 0;
+}