initializer_list: Decorate with constexpr.

* libsupc++/initializer_list: Decorate with constexpr.

Co-Authored-By: Benjamin Kosnik <bkoz@redhat.com>

From-SVN: r166170

gcc/testsuite/ChangeLog

@@ -1,6 +1,9 @@
 2010-11-01  Jason Merrill  <jason@redhat.com>
 	    Benjamin Kosnik  <bkoz@redhat.com>
 
+	* g++.dg/cpp0x/constexpr-initlist2.C: New.
+	* g++.dg/cpp0x/constexpr-initlist3.C: New.
+
 	* g++.dg/cpp0x/constexpr-array-ptr.C: New.
 	* g++.dg/cpp0x/constexpr-array-ptr2.C: New.
 	* g++.dg/cpp0x/constexpr-array-ptr3.C: New.

gcc/testsuite/g++.dg/cpp0x/constexpr-initlist2.C

@@ -0,0 +1,10 @@
+// { dg-options -std=c++0x }
+
+#include <initializer_list>
+
+constexpr auto list = { 1, 2, 3, 4 };
+
+#define SA(X) static_assert(X, #X)
+SA(list.size() == 4);
+SA(list.begin()[2] == 3);
+SA(list.end()[-1] == 4);

gcc/testsuite/g++.dg/cpp0x/constexpr-initlist3.C

@@ -0,0 +1,12 @@
+// { dg-options -std=c++0x }
+
+#include <initializer_list>
+#define SA(X) static_assert(X,#X)
+
+constexpr int f(std::initializer_list<int> l) { return l.begin()[0]; }
+
+int main()
+{
+  constexpr int i = f({42});
+  SA(i==42);
+}

libstdc++-v3/ChangeLog

@@ -1,3 +1,7 @@
+2010-11-01  Jason Merrill  <jason@redhat.com>
+
+	* libsupc++/initializer_list: Decorate with constexpr.
+
 2010-11-01  Jonathan Wakely  <jwakely.gcc@gmail.com>
 
 	PR libstdc++/45999

libstdc++-v3/libsupc++/initializer_list

@@ -57,23 +57,23 @@ namespace std
       size_type			_M_len;
 
       // The compiler can call a private constructor.
-      initializer_list(const_iterator __a, size_type __l)
+      constexpr initializer_list(const_iterator __a, size_type __l)
       : _M_array(__a), _M_len(__l) { }
 
     public:
-      initializer_list() : _M_array(0), _M_len(0) { }
+      constexpr initializer_list() : _M_array(0), _M_len(0) { }
 
       // Number of elements.
-      size_type
+      constexpr size_type
-      size() const { return _M_len; }
+      size() { return _M_len; }
 
       // First element.
-      const_iterator
+      constexpr const_iterator
-      begin() const { return _M_array; }
+      begin() { return _M_array; }
 
       // One past the last element.
-      const_iterator
+      constexpr const_iterator
-      end() const { return begin() + size(); }
+      end() { return begin() + size(); }
   };
 
   /**
@@ -82,7 +82,7 @@ namespace std
    *  @param  il  Initializer list.
    */
   template<class _Tp>
-    inline const _Tp*
+    constexpr const _Tp*
     begin(initializer_list<_Tp> __ils)
     { return __ils.begin(); }
 
@@ -92,7 +92,7 @@ namespace std
    *  @param  il  Initializer list.
    */
   template<class _Tp>
-    inline const _Tp*
+    constexpr const _Tp*
     end(initializer_list<_Tp> __ils)
     { return __ils.end(); }
 }