Add pretty-printing support for __is_nothrow_{assignable, constructible}. [PR98054]

[Ville Voutilainen via Gcc-patches]

OK for trunk if full testsuite passes? Should we consider having some sort
of test that catches such omissions?

2020-11-30  Ville Voutilainen  <ville.voutilai...@gmail.com>

    gcc/

    PR c++/98054
    * cp/cxx-pretty-print.c (pp_cxx_trait_expression):
    Add support for __is_nothrow_{assignable,constructible}.

diff --git a/gcc/cp/cxx-pretty-print.c b/gcc/cp/cxx-pretty-print.c
index 058b9c2f4fc..1cdf0772a6b 100644
--- a/gcc/cp/cxx-pretty-print.c
+++ b/gcc/cp/cxx-pretty-print.c
@@ -2666,6 +2666,12 @@ pp_cxx_trait_expression (cxx_pretty_printer *pp, tree t)
     case CPTK_IS_CONSTRUCTIBLE:
       pp_cxx_ws_string (pp, "__is_constructible");
       break;
+    case CPTK_IS_NOTHROW_ASSIGNABLE:
+      pp_cxx_ws_string (pp, "__is_nothrow_assignable");
+      break;
+    case CPTK_IS_NOTHROW_CONSTRUCTIBLE:
+      pp_cxx_ws_string (pp, "__is_nothrow_constructible");
+      break;
 
     default:
       gcc_unreachable ();