[C++ Patch] DR 1453

[Paolo Carlini]

Hi,

while looking into c++/58102 and DR 1405 I noticed that we don't 
implement DR 1453 either, sort of dual issue with volatile instead of 
mutable. Tested x86_64-linux.

Thanks,
Paolo.

////////////////////////
/cp
2014-09-02  Paolo Carlini  <paolo.carl...@oracle.com>

        DR 1453
        * class.c (check_field_decls): A class of literal type cannot have
        volatile non-static data members and base classes.
        (explain_non_literal_class): Update.

/testsuite
2014-09-02  Paolo Carlini  <paolo.carl...@oracle.com>

        DR 1453
        * g++.dg/cpp0x/constexpr-volatile.C: New.
        * g++.dg/ext/is_literal_type2.C: Likewise.
Index: cp/class.c
===================================================================
--- cp/class.c  (revision 214808)
+++ cp/class.c  (working copy)
@@ -3528,9 +3528,11 @@ check_field_decls (tree t, tree *access_decls,
        CLASSTYPE_NON_AGGREGATE (t) = 1;
 
       /* If at least one non-static data member is non-literal, the whole
-         class becomes non-literal.  Note: if the type is incomplete we
-        will complain later on.  */
-      if (COMPLETE_TYPE_P (type) && !literal_type_p (type))
+         class becomes non-literal.  Per Core/1453, volatile non-static
+        data members and base classes are also not allowed.
+        Note: if the type is incomplete we will complain later on.  */
+      if (COMPLETE_TYPE_P (type)
+         && (!literal_type_p (type) || CP_TYPE_VOLATILE_P (type))) 
         CLASSTYPE_LITERAL_P (t) = false;
 
       /* A standard-layout class is a class that:
@@ -5431,6 +5433,9 @@ explain_non_literal_class (tree t)
              if (CLASS_TYPE_P (ftype))
                explain_non_literal_class (ftype);
            }
+         if (CP_TYPE_VOLATILE_P (ftype))
+           inform (0, "  non-static data member %q+D has "
+                   "volatile type", field);
        }
     }
 }
Index: testsuite/g++.dg/cpp0x/constexpr-volatile.C
===================================================================
--- testsuite/g++.dg/cpp0x/constexpr-volatile.C (revision 0)
+++ testsuite/g++.dg/cpp0x/constexpr-volatile.C (working copy)
@@ -0,0 +1,26 @@
+// DR 1453
+// { dg-do compile { target c++11 } }
+
+struct S {
+  constexpr S() : n{} { }
+  volatile int n;
+};
+
+constexpr S s;  // { dg-error "literal" }
+
+struct Z {
+  volatile int m;
+};
+
+struct T {
+  constexpr T() : n{} { }
+  Z n;
+};
+
+constexpr T t;  // { dg-error "literal" }
+
+struct U : Z {
+  constexpr U() : Z{} { }
+};
+
+constexpr U u;  // { dg-error "literal" }
Index: testsuite/g++.dg/ext/is_literal_type2.C
===================================================================
--- testsuite/g++.dg/ext/is_literal_type2.C     (revision 0)
+++ testsuite/g++.dg/ext/is_literal_type2.C     (working copy)
@@ -0,0 +1,26 @@
+// DR 1453
+// { dg-do compile { target c++11 } }
+
+struct S {
+  constexpr S() : n{} { }
+  volatile int n;
+};
+
+static_assert(!__is_literal_type(S), "");
+
+struct Z {
+  volatile int m;
+};
+
+struct T {
+  constexpr T() : n{} { }
+  Z n;
+};
+
+static_assert(!__is_literal_type(T), "");
+
+struct U : Z {
+  constexpr U() : Z{} { }
+};
+
+static_assert(!__is_literal_type(U), "");