constexpr.c (literal_type_p): Return true for void type in C++14.

	* constexpr.c (literal_type_p): Return true for void type in C++14.

	* g++.dg/cpp0x/constexpr-function2.C: Limit dg-error to C++11.
	* g++.dg/cpp0x/constexpr-neg1.C: Likewise.
	* g++.dg/cpp1y/constexpr-void1.C: New test.

From-SVN: r218220

gcc/cp/ChangeLog

+2014-12-01  Marek Polacek  <polacek@redhat.com>
+
+	* constexpr.c (literal_type_p): Return true for void type in C++14.
+
 2014-12-01  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/60845

gcc/cp/constexpr.c

@@ -59,7 +59,8 @@ literal_type_p (tree t)
 {
   if (SCALAR_TYPE_P (t)
       || TREE_CODE (t) == VECTOR_TYPE
-      || TREE_CODE (t) == REFERENCE_TYPE)
+      || TREE_CODE (t) == REFERENCE_TYPE
+      || (VOID_TYPE_P (t) && cxx_dialect >= cxx14))
     return true;
   if (CLASS_TYPE_P (t))
     {

gcc/testsuite/ChangeLog

+2014-12-01  Marek Polacek  <polacek@redhat.com>
+
+	* g++.dg/cpp0x/constexpr-function2.C: Limit dg-error to C++11.
+	* g++.dg/cpp0x/constexpr-neg1.C: Likewise.
+	* g++.dg/cpp1y/constexpr-void1.C: New test.
+
 2014-12-01  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/60845

gcc/testsuite/g++.dg/cpp0x/constexpr-function2.C

@@ -23,7 +23,7 @@ constexpr int area = squarei(side); // { dg-error "side|argument" }
 int next(constexpr int x) // { dg-error "parameter" }
 { return x + 1; }
 
-constexpr void f(int x)       // { dg-error "return type .void" }
+constexpr void f(int x)       // { dg-error "return type .void" "" { target c++11_only } }
 { /* ... */ }
 
 constexpr int prev(int x)

gcc/testsuite/g++.dg/cpp0x/constexpr-neg1.C

@@ -29,7 +29,7 @@ int next(constexpr int x) {	// { dg-error "parameter" }
 extern constexpr int memsz;	// { dg-error "definition" }
 
 // error: return type is void
-constexpr void f(int x)		// { dg-error "void" }
+constexpr void f(int x)		// { dg-error "void" "" { target c++11_only } }
 { /* ... */ }
 // error: use of decrement
 constexpr int prev(int x)

gcc/testsuite/g++.dg/cpp1y/constexpr-void1.C

+// { dg-do compile { target c++14 } }
+
+struct S
+{
+  int i = 20;
+
+  constexpr void
+  foo (void)
+  {
+    if (i > 20)
+      __builtin_abort ();
+  }
+};