Core issue 1331 - const mismatch with defaulted copy constructor

	Core issue 1331 - const mismatch with defaulted copy constructor
	* class.c (check_bases_and_members): When checking a defaulted
	function, mark it as deleted rather than giving an error.

	* g++.dg/cpp0x/defaulted15.C (struct F): Remove dg-error.
	* g++.dg/cpp0x/defaulted52.C: New test.
	* g++.dg/cpp0x/defaulted53.C: New test.
	* g++.dg/cpp0x/defaulted54.C: New test.
	* g++.dg/cpp0x/defaulted55.C: New test.
	* g++.dg/cpp0x/defaulted56.C: New test.
	* g++.dg/cpp0x/defaulted57.C: New test.
	* g++.dg/cpp0x/defaulted58.C: New test.
	* g++.dg/cpp0x/defaulted59.C: New test.
	* g++.dg/cpp0x/defaulted60.C: New test.

From-SVN: r261526

gcc/cp/ChangeLog

+2018-06-12  Marek Polacek  <polacek@redhat.com>
+
+	Core issue 1331 - const mismatch with defaulted copy constructor
+	* class.c (check_bases_and_members): When checking a defaulted
+	function, mark it as deleted rather than giving an error.
+
 2018-06-11  Jason Merrill  <jason@redhat.com>
 
 	PR c++/85792 -Wctor-dtor-privacy and inherited constructor.

gcc/cp/class.c

@@ -5660,9 +5660,9 @@ check_bases_and_members (tree t)
 
 	    if (fn_const_p && !imp_const_p)
 	      /* If the function is defaulted outside the class, we just
-		 give the synthesis error.  */
-	      error ("%q+D declared to take const reference, but implicit "
-		     "declaration would take non-const", fn);
+		 give the synthesis error.  Core Issue #1331 says this is
+		 no longer ill-formed, it is defined as deleted instead.  */
+	      DECL_DELETED_FN (fn) = true;
 	  }
 	defaulted_late_check (fn);
       }

gcc/testsuite/ChangeLog

+2018-06-12  Marek Polacek  <polacek@redhat.com>
+
+	Core issue 1331 - const mismatch with defaulted copy constructor
+	* g++.dg/cpp0x/defaulted15.C (struct F): Remove dg-error.
+	* g++.dg/cpp0x/defaulted52.C: New test.
+	* g++.dg/cpp0x/defaulted53.C: New test.
+	* g++.dg/cpp0x/defaulted54.C: New test.
+	* g++.dg/cpp0x/defaulted55.C: New test.
+	* g++.dg/cpp0x/defaulted56.C: New test.
+	* g++.dg/cpp0x/defaulted57.C: New test.
+	* g++.dg/cpp0x/defaulted58.C: New test.
+	* g++.dg/cpp0x/defaulted59.C: New test.
+	* g++.dg/cpp0x/defaulted60.C: New test.
+
 2018-06-12  David Malcolm  <dmalcolm@redhat.com>
 
 	PR other/69968

gcc/testsuite/g++.dg/cpp0x/defaulted15.C

@@ -48,8 +48,7 @@ struct F
 
 struct G: public F
 {
-  // Can't be const because F copy ctor isn't.
-  G(const G&) = default;	// { dg-error "const" }
+  G(const G&) = default;
 };
 
 struct H

gcc/testsuite/g++.dg/cpp0x/defaulted52.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+struct M
+{
+  M();
+  // So that W wouldn't have had "const W&" copy ctor if it were
+  // implicitly declared.
+  M(M&);
+};
+
+template<typename T> struct W
+{
+  W();
+  // This should now compile and be =deleted.
+  W(const W&) = default;
+  T t;
+};
+
+W<M> w;

gcc/testsuite/g++.dg/cpp0x/defaulted53.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+struct M
+{
+  M& operator=(M&);
+};
+
+struct R
+{
+  R& operator=(R&) = default;
+  M m;
+};
+
+struct S
+{
+  S& operator=(const S&) = default;
+  M m;
+};
+
+struct T
+{
+  // If F is an assignment operator, and the return type of T1
+  // differs from the return type of T2 the program is ill-formed.
+  T operator=(T&) = default; // { dg-error "defaulted" }
+  M m;
+};
+
+struct U
+{
+  // If F is an assignment operator, and T1's parameter type is
+  // not a reference, the program is ill-formed.
+  U& operator=(U) = default; // { dg-error "defaulted" }
+  M m;
+};

gcc/testsuite/g++.dg/cpp0x/defaulted54.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+struct M
+{
+  M();
+  M(M&);
+};
+
+template<typename T> struct W
+{
+  W();
+  W(const W&) = default; // { dg-error "binding" }
+  T t;
+};
+
+W<M> w;
+W<M> w2 = w; // { dg-error "use of deleted function" }

gcc/testsuite/g++.dg/cpp0x/defaulted55.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+struct M
+{
+  M();
+  M(M&);
+};
+
+template<typename T> struct W
+{
+  W();
+  W(W&) = default;
+  // T1 and T2 may have differing ref-qualifiers (copy assign op).
+  constexpr W& operator=(const W&) && = default; // { dg-error "defaulted" "" { target c++11_down } }
+  T t;
+};
+
+W<M> w;

gcc/testsuite/g++.dg/cpp0x/defaulted56.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+// If T2 (what would be the implicit declaration) has a parameter of
+// type const C&, the corresponding parameter of T1 may be of type C&.
+
+struct S
+{
+  constexpr S(S &) = default;
+};
+
+struct T
+{
+  constexpr T(volatile T &) = default; // { dg-error "defaulted" }
+};
+
+struct U
+{
+  constexpr U(const volatile U &) = default; // { dg-error "defaulted" }
+};
+
+struct V
+{
+  constexpr V(const V &) = default;
+};

gcc/testsuite/g++.dg/cpp0x/defaulted57.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+// If T2 (what would be the implicit declaration) has a parameter of
+// type const C&, the corresponding parameter of T1 may be of type C&.
+
+struct S
+{
+  S& operator=(S &) = default;
+};
+
+struct T
+{
+  T& operator=(volatile T &) = default; // { dg-error "defaulted" }
+};
+
+struct U
+{
+  U& operator=(const volatile U &) = default; // { dg-error "defaulted" }
+};
+
+struct V
+{
+  V& operator=(const V &) = default;
+};

gcc/testsuite/g++.dg/cpp0x/defaulted58.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+struct M
+{
+  M() = default;
+  M& operator=(M&);
+};
+
+template<typename T> struct W
+{
+  W() = default;
+  W& operator=(const W&) = default; // { dg-error "binding" }
+  T t;
+};
+
+int
+main ()
+{
+  W<M> w1, w2;
+  w1 = w2; // { dg-error "use of deleted function" }
+}

gcc/testsuite/g++.dg/cpp0x/defaulted59.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+struct M
+{
+  M(M&) = default;
+};
+
+struct W : public M
+{
+  W(const W&) = default;
+};

gcc/testsuite/g++.dg/cpp0x/defaulted60.C

+// Core Issue #1331 (const mismatch with defaulted copy constructor)
+// { dg-do compile { target c++11 } }
+
+struct M
+{
+  M(M&);
+};
+
+struct W
+{
+  W();
+  W(const W&);
+  M m;
+};
+
+// Not first declaration.
+W::W(const W&) = default; // { dg-error "binding" }
+W w;