Log(N) complexity and templates depth in make_index_seq_impl, avoid usage of slow sizeof...(I), workaround GCC ICE in constexpr tests

test/type_index_constexpr_test.cpp

@@ -74,16 +74,20 @@ void search_same() {
     );
 }
 
-/*
-#ifndef BOOST_NO_CXX14_CONSTEXPR
+template <class T, std::size_t N>
+BOOST_CXX14_CONSTEXPR bool in_namespace(const char (&ns)[N]) BOOST_NOEXCEPT {
+    BOOST_CXX14_CONSTEXPR const char* name = boost::typeindex::ctti_type_index::type_id<T>().raw_name();
+    for (std::size_t i = 0; i < N - 1; ++i)
+        if (name[i] != ns[i])
+            return false;
+            
+    return true;
+}
+
 template <class T>
-struct is_boost_namespace {
-    static constexpr char cb[5] = {'b', 'o', 'o', 's', 't'};
-    static constexpr boost::typeindex::ctti_type_index type = boost::typeindex::ctti_type_index::type_id<T>();
-    static constexpr bool value = (boost::typeindex::detail::constexpr_search(type.name(), type.name() + 5, cb, cb + 5) != cb + 5);
-};
-#endif
-*/
+BOOST_CXX14_CONSTEXPR bool is_boost_namespace() BOOST_NOEXCEPT {
+    return in_namespace<T>("boost::");
+}
 
 void constexpr_test() {
     using namespace boost::typeindex;
@@ -127,15 +131,12 @@ void constexpr_test() {
 
     BOOST_CXX14_CONSTEXPR const char* short_name = t_short0.name();
     BOOST_TEST(*short_name != '\0');
-/*
-#ifndef BOOST_NO_CXX14_CONSTEXPR
-    constexpr bool in_namespace = is_boost_namespace<ctti_type_index>::value;
+
+    BOOST_CXX14_CONSTEXPR bool in_namespace = is_boost_namespace<ctti_type_index>();
     BOOST_TEST(in_namespace);
 
-    constexpr bool not_in_namespace = !is_boost_namespace<std::string>::value;
+    BOOST_CXX14_CONSTEXPR bool not_in_namespace = !is_boost_namespace<std::string>();
     BOOST_TEST(not_in_namespace);
-#endif
-*/
 }