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[C++2A] Implement P1008R1 - prohibit aggregates with user-declared constructors


Hi!

Seems what is considered an aggregate type keeps changing in every single
C++ version.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2018-07-27  Jakub Jelinek  <jakub@redhat.com>

	P1008R1 - prohibit aggregates with user-declared constructors
	* class.c (check_bases_and_members): For C++2a set
	CLASSTYPE_NON_AGGREGATE based on TYPE_HAS_USER_CONSTRUCTOR rather than
	type_has_user_provided_or_explicit_constructor.

	* g++.dg/ext/is_aggregate.C: Add tests with deleted or defaulted ctor.
	* g++.dg/cpp0x/defaulted1.C (main): Ifdef out for C++2a B b = {1};.
	* g++.dg/cpp0x/deleted2.C: Expect error for C++2a.
	* g++.dg/cpp2a/aggr1.C: New test.
	* g++.dg/cpp2a/aggr2.C: New test.

--- gcc/cp/class.c.jj	2018-07-25 18:46:56.168149411 +0200
+++ gcc/cp/class.c	2018-07-27 21:21:22.382933221 +0200
@@ -5571,7 +5571,9 @@ check_bases_and_members (tree t)
      Again, other conditions for being an aggregate are checked
      elsewhere.  */
   CLASSTYPE_NON_AGGREGATE (t)
-    |= (type_has_user_provided_or_explicit_constructor (t)
+    |= ((cxx_dialect < cxx2a
+	 ? type_has_user_provided_or_explicit_constructor (t)
+	 : TYPE_HAS_USER_CONSTRUCTOR (t))
 	|| TYPE_POLYMORPHIC_P (t));
   /* This is the C++98/03 definition of POD; it changed in C++0x, but we
      retain the old definition internally for ABI reasons.  */
--- gcc/testsuite/g++.dg/ext/is_aggregate.C.jj	2017-03-31 08:39:08.141481789 +0200
+++ gcc/testsuite/g++.dg/ext/is_aggregate.C	2018-07-27 21:46:58.832053123 +0200
@@ -61,6 +61,8 @@ struct K { int a, b; virtual void foo ()
 struct L : virtual public A { int d, e; };
 struct M : protected A { int d, e; };
 struct N : private A { int d, e; };
+struct O { O () = delete; int a, b, c; };
+struct P { P () = default; int a, b, c; };
 typedef int T;
 typedef float U;
 typedef int V __attribute__((vector_size (4 * sizeof (int))));
@@ -94,6 +96,13 @@ main ()
   assert (NTEST (L));
   assert (NTEST (M));
   assert (NTEST (N));
+#if __cplusplus > 201703L
+  assert (NTEST (O));
+  assert (NTEST (P));
+#else
+  assert (PTEST (O));
+  assert (PTEST (P));
+#endif
   assert (PTEST (int[]));
   assert (PTEST (double[]));
   assert (PTEST (T[2]));
@@ -114,4 +123,6 @@ main ()
   assert (PTEST (L[]));
   assert (PTEST (M[6]));
   assert (PTEST (N[]));
+  assert (PTEST (O[]));
+  assert (PTEST (P[]));
 }
--- gcc/testsuite/g++.dg/cpp0x/defaulted1.C.jj	2014-03-10 10:50:13.280983792 +0100
+++ gcc/testsuite/g++.dg/cpp0x/defaulted1.C	2018-07-27 22:03:48.425103195 +0200
@@ -23,7 +23,9 @@ struct B
 int main()
 {
   A a1, a2;
+#if __cplusplus <= 201703L
   B b = {1};
+#endif
   a1 = a2;
 }
 
--- gcc/testsuite/g++.dg/cpp0x/deleted2.C.jj	2013-12-09 14:32:14.279033576 +0100
+++ gcc/testsuite/g++.dg/cpp0x/deleted2.C	2018-07-27 22:04:35.539198867 +0200
@@ -6,4 +6,4 @@ struct A {
  A() = delete;
 };
 
-A a = {1};
+A a = {1};	// { dg-error "could not convert" "" { target c++2a } }
--- gcc/testsuite/g++.dg/cpp2a/aggr1.C.jj	2018-07-27 21:33:20.566391559 +0200
+++ gcc/testsuite/g++.dg/cpp2a/aggr1.C	2018-07-27 22:06:09.093388836 +0200
@@ -0,0 +1,15 @@
+// { dg-do compile { target c++11 } }
+struct A {
+  A () = delete;	// { dg-message "declared here" "" { target c++2a } }
+};
+struct B {
+  B () = default;
+  int b = 0;
+};
+struct C {
+  C (C&&) = default;	// { dg-message "candidate" "" { target c++2a } }
+  int c, d;
+};
+A a {};			// { dg-error "use of deleted function" "" { target c++2a } }
+B b = {1};		// { dg-error "could not convert" "" { target { c++11_only || c++2a } } }
+C *c = new C {2, 3};	// { dg-error "no matching function for call to" "" { target c++2a } }
--- gcc/testsuite/g++.dg/cpp2a/aggr2.C.jj	2018-07-27 22:10:51.956963223 +0200
+++ gcc/testsuite/g++.dg/cpp2a/aggr2.C	2018-07-27 22:15:20.820509168 +0200
@@ -0,0 +1,25 @@
+// { dg-do run { target c++11 } }
+
+struct A;
+struct B { operator A (); };
+struct A { A (const A &) = default; A () = default; B a; };
+A a {B {}};
+bool seen;
+
+B::operator A ()
+{
+  seen = true;
+  return A ();
+}
+
+int
+main ()
+{
+#if __cplusplus > 201703L
+  if (!seen)
+    __builtin_abort ();
+#else
+  if (seen)
+    __builtin_abort ();
+#endif
+}

	Jakub


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