[C++ PATCH] With -Wuseless-cast on direct enum init (PR c++/82299)

[Jakub Jelinek]

Hi!

The casts added for the C++17 direct enum initialization IMNSHO shouldn't
trigger -Wuseless-cast warnings.

Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2017-09-29  Jakub Jelinek  <ja...@redhat.com>

        PR c++/82299
        * decl.c (reshape_init): Suppress warn_useless_cast for direct enum
        init.
        * typeck.c (convert_for_assignment): Likewise.

        * g++.dg/cpp0x/pr82299.C: New test.

--- gcc/cp/decl.c.jj    2017-09-29 11:21:55.000000000 +0200
+++ gcc/cp/decl.c       2017-09-29 15:19:02.549548102 +0200
@@ -6053,7 +6053,10 @@ reshape_init (tree type, tree init, tsub
       tree elt = CONSTRUCTOR_ELT (init, 0)->value;
       type = cv_unqualified (type);
       if (check_narrowing (ENUM_UNDERLYING_TYPE (type), elt, complain))
-       return cp_build_c_cast (type, elt, tf_warning_or_error);
+       {
+         warning_sentinel w (warn_useless_cast);
+         return cp_build_c_cast (type, elt, tf_warning_or_error);
+       }
       else
        return error_mark_node;
     }
--- gcc/cp/typeck.c.jj  2017-09-29 09:07:33.000000000 +0200
+++ gcc/cp/typeck.c     2017-09-29 15:21:17.770926572 +0200
@@ -8527,7 +8527,10 @@ convert_for_assignment (tree type, tree
     {
       tree elt = CONSTRUCTOR_ELT (rhs, 0)->value;
       if (check_narrowing (ENUM_UNDERLYING_TYPE (type), elt, complain))
-       rhs = cp_build_c_cast (type, elt, complain);
+       {
+         warning_sentinel w (warn_useless_cast);
+         rhs = cp_build_c_cast (type, elt, complain);
+       }
       else
        rhs = error_mark_node;
     }
--- gcc/testsuite/g++.dg/cpp0x/pr82299.C.jj     2017-09-29 15:24:18.909754416 
+0200
+++ gcc/testsuite/g++.dg/cpp0x/pr82299.C        2017-09-29 15:29:15.589237065 
+0200
@@ -0,0 +1,9 @@
+// PR c++/82299
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wuseless-cast" }
+
+enum Enum : char { A = 0, B = 1 };
+
+struct S {
+  Enum e { Enum::A };  // { dg-bogus "useless cast to type" }
+};

        Jakub