PR c++/92560 - ICE with decltype and rewritten operator.

A call as the immediate operand of decltype is handled differently; we don't
create an object of the return type as we do normally.  But in the case of a
rewritten operator, we're adding another call as a wrapper, so the inner
call doesn't get the special handling.

	* call.c (build_new_op_1): Clear tf_decltype on inner call.

From-SVN: r279183

gcc/cp/ChangeLog

+2019-12-10  Jason Merrill  <jason@redhat.com>
+
+	PR c++/92560 - ICE with decltype and rewritten operator.
+	* call.c (build_new_op_1): Clear tf_decltype on inner call.
+
 2019-12-09  David Malcolm  <dmalcolm@redhat.com>
 
 	* error.c (range_label_for_type_mismatch::get_text): Replace

gcc/cp/call.c

@@ -6242,6 +6242,10 @@ build_new_op_1 (const op_location_t &loc, enum tree_code code, int flags,
 	    result = error_mark_node;
 	  else
 	    {
+	      tsubst_flags_t ocomplain = complain;
+	      if (cand->rewritten ())
+		/* We'll wrap this call in another one.  */
+		ocomplain &= ~tf_decltype;
 	      if (cand->reversed ())
 		{
 		  /* We swapped these in add_candidate, swap them back now.  */
@@ -6251,7 +6255,7 @@ build_new_op_1 (const op_location_t &loc, enum tree_code code, int flags,
 				"current function recursively with reversed "
 				"arguments");
 		}
-	      result = build_over_call (cand, LOOKUP_NORMAL, complain);
+	      result = build_over_call (cand, LOOKUP_NORMAL, ocomplain);
 	    }
 
 	  if (trivial_fn_p (cand->fn))

gcc/testsuite/g++.dg/cpp2a/spaceship-decltype1.C

+// PR c++/92560
+// { dg-do compile { target c++2a } }
+
+#include <compare>
+
+struct X
+{
+  friend std::strong_ordering operator<=>(X, X);
+} x;
+
+using T = decltype(x < x);