SFINAE __bit_iterator such that it will only get instantiated with a container that has the nested type __storage_type.  This prevents accidental instantiation such as in http://llvm.org/bugs/show_bug.cgi?id=12755.  This fixes http://llvm.org/bugs/show_bug.cgi?id=12755.

llvm-svn: 156308
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 0ae9efeb1a14a665a0f5d6819e25a83cc6ea348a
diff --git a/include/bitset b/include/bitset
index 6e12e5c..b3a5867 100644
--- a/include/bitset
+++ b/include/bitset
@@ -148,9 +148,9 @@
 public:
     typedef ptrdiff_t              difference_type;
     typedef size_t                 size_type;
+    typedef size_type              __storage_type;
 protected:
     typedef __bitset __self;
-    typedef size_type              __storage_type;
     typedef       __storage_type*  __storage_pointer;
     typedef const __storage_type*  __const_storage_pointer;
     static const unsigned __bits_per_word = static_cast<unsigned>(sizeof(__storage_type) * CHAR_BIT);
@@ -406,9 +406,9 @@
 public:
     typedef ptrdiff_t              difference_type;
     typedef size_t                 size_type;
+    typedef size_type              __storage_type;
 protected:
     typedef __bitset __self;
-    typedef size_type              __storage_type;
     typedef       __storage_type*  __storage_pointer;
     typedef const __storage_type*  __const_storage_pointer;
     static const unsigned __bits_per_word = static_cast<unsigned>(sizeof(__storage_type) * CHAR_BIT);
@@ -549,9 +549,9 @@
 public:
     typedef ptrdiff_t              difference_type;
     typedef size_t                 size_type;
+    typedef size_type              __storage_type;
 protected:
     typedef __bitset __self;
-    typedef size_type              __storage_type;
     typedef       __storage_type*  __storage_pointer;
     typedef const __storage_type*  __const_storage_pointer;
     static const unsigned __bits_per_word = static_cast<unsigned>(sizeof(__storage_type) * CHAR_BIT);