diff --git a/CMakeLists.txt b/CMakeLists.txt
index 29eb007..0fb16b3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,6 +10,10 @@ set(librexy_VERSION_REVISION 0)
 set(INCLUDE_PATH ${CMAKE_SOURCE_DIR}/include)
 include_directories(BEFORE SYSTEM "${INCLUDE_PATH}")
 
+#find_program(CMAKE_CXX_CPPCHECK NAMES cppcheck)
+#if(CMAKE_CXX_CPPCHECK)
+#	list(APPEND CMAKE_CXX_CPPCHECK "--enable=warning" "--inconclusive" "--force" "--inline-suppr")
+#endif()
 
 cmake_dependent_option(ENABLE_SHARED "Build shared library" ON "NOT BUILD_HEADER_ONLY" OFF)
 cmake_dependent_option(ENABLE_SSO "Use small string optimization" ON "NOT BUILD_HEADER_ONLY" ON)
diff --git a/include/rexy/allocator.hpp b/include/rexy/allocator.hpp
index 3272898..6178d43 100644
--- a/include/rexy/allocator.hpp
+++ b/include/rexy/allocator.hpp
@@ -20,7 +20,7 @@
 #define REXY_DEFAULT_ALLOCATOR_HPP
 
 #include <cstddef> //ptrdiff_t, size_t
-#include <type_traits> //true_type, false_type, is_constant_evaluated
+#include <type_traits> //true_type, false_type
 #include <new>
 #include <limits> //numeric_limits
 
@@ -37,6 +37,7 @@
 
 #include "rexy.hpp"
 #include "compat/standard.hpp"
+#include "compat/if_consteval.hpp"
 
 #include <type_traits> //declval
 
@@ -82,11 +83,7 @@ namespace rexy{
 		REXY_CPP20_CONSTEXPR pointer allocate(size_type n){
 			size_type bytes = has_overflow(n) ? std::numeric_limits<size_type>::max() : n*sizeof(T);
 
-			#ifdef __cpp_if_consteval
-				if consteval{  //} //makes my braces matcher in nano not upset ;)
-			#else
-				if(std::is_constant_evaluated()){
-			#endif //__cpp_if_consteval
+			REXY_if_consteval{
 					std::allocator<value_type> a;
 					const size_type num_items = n / sizeof(value_type);
 					return a.allocate(num_items);
@@ -101,11 +98,7 @@ namespace rexy{
 
 
 		REXY_CPP20_CONSTEXPR void deallocate(pointer p, size_type n){
-			#ifdef __cpp_if_consteval
-				if consteval{  //} //makes my braces matcher in nano not upset ;)
-			#else
-				if(std::is_constant_evaluated()){
-			#endif
+			REXY_if_consteval{
 					std::allocator<value_type> a;
 					const size_type num_items = n / sizeof(value_type);
 					return a.deallocate(p, num_items);
diff --git a/include/rexy/compat/if_consteval.hpp b/include/rexy/compat/if_consteval.hpp
new file mode 100644
index 0000000..7fb4a7b
--- /dev/null
+++ b/include/rexy/compat/if_consteval.hpp
@@ -0,0 +1,30 @@
+/**
+	This file is a part of rexy's general purpose library
+	Copyright (C) 2022 rexy712
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef REXY_if_consteval
+
+#if defined(__cpp_if_consteval)
+	#define REXY_if_consteval if consteval
+	#define REXY_if_consteval if not consteval
+#elif defined(__cpp_lib_is_constant_evaluated)
+	#include <type_traits> //is_constant_evaluated
+	#define REXY_if_consteval if(std::is_constant_evaluated())
+	#define REXY_if_not_consteval if(!std::is_constant_evaluated())
+#endif //__cpp_if_consteval
+
+#endif
diff --git a/include/rexy/compat/standard.hpp b/include/rexy/compat/standard.hpp
index 2b269b6..9f994fe 100644
--- a/include/rexy/compat/standard.hpp
+++ b/include/rexy/compat/standard.hpp
@@ -29,11 +29,14 @@
 
 	#if __cplusplus >= 202300L
 		#define REXY_STANDARD_CPP23
-	#elif __cplusplus >= 202002L
+	#endif
+	#if __cplusplus >= 202002L
 		#define REXY_STANDARD_CPP20
-	#elif __cplusplus >= 201703L
+	#endif
+	#if __cplusplus >= 201703L
 		#define REXY_STANDARD_CPP17
-	#else //__cplusplus
+	#endif
+	#if __cplusplus < 201703L
 		#error "Requires minimum C++17 standard"
 	#endif //__cplusplus
 
diff --git a/include/rexy/concepts/string.hpp b/include/rexy/concepts/string.hpp
index d7ed044..503d90d 100644
--- a/include/rexy/concepts/string.hpp
+++ b/include/rexy/concepts/string.hpp
@@ -29,9 +29,41 @@ namespace rexy{
 
 	template<class Left, class Right>
 	class string_cat_expr;
+	template<class Char, REXY_ALLOCATOR_CONCEPT Alloc>
+	class basic_string;
+	template<class Char>
+	class basic_string_view;
+
+	template<class T>
+	struct is_basic_string{
+		template<class Char, class Alloc>
+		static std::true_type check(const basic_string<Char,Alloc>*);
+		static std::false_type check(...);
+
+		static constexpr bool value = decltype(check(std::declval<std::remove_cvref_t<T>*>()))::value;
+	};
+
+	template<class T>
+	struct is_basic_string_view{
+		template<class Char>
+		static std::true_type check(const basic_string_view<Char>*);
+		static std::false_type check(...);
+
+		static constexpr bool value = decltype(check(std::declval<std::remove_cvref_t<T>*>()))::value;
+	};
+
+	template<class T>
+	struct is_basic_string_expr{
+		template<class Left, class Right>
+		static std::true_type check(const string_cat_expr<Left,Right>*);
+		static std::false_type check(...);
+
+		static constexpr bool value = decltype(check(std::declval<std::remove_cvref_t<T>*>()))::value;
+	};
 
 	template<class T>
 	concept BasicString = requires(const T& a){
+		requires(is_basic_string<T>::value || is_basic_string_view<T>::value);
 		{std::as_const(a).length()} -> std::convertible_to<typename std::decay_t<T>::size_type>;
 		{std::as_const(a).c_str()} -> std::convertible_to<typename std::decay_t<T>::const_pointer>;
 		{std::as_const(a)[0]} -> std::convertible_to<typename std::decay_t<T>::const_reference>;
@@ -39,7 +71,7 @@ namespace rexy{
 		{std::as_const(a).end()} -> std::convertible_to<typename std::decay_t<T>::const_iterator>;
 	};
 	template<class T>
-	concept StringExpr = rexy::is_template_type<T,string_cat_expr>::value;
+	concept StringExpr = is_basic_string_expr<T>::value;
 	template<class T>
 	concept String = BasicString<T> || StringExpr<T>;
 
diff --git a/include/rexy/detail/format/parse_context.tpp b/include/rexy/detail/format/parse_context.tpp
index 308d56a..8403322 100644
--- a/include/rexy/detail/format/parse_context.tpp
+++ b/include/rexy/detail/format/parse_context.tpp
@@ -19,12 +19,13 @@
 #ifndef REXY_DETAIL_FORMAT_PARSE_CONTEXT_TPP
 #define REXY_DETAIL_FORMAT_PARSE_CONTEXT_TPP
 
+#include "../../compat/if_consteval.hpp"
+
 #include "parse_context.hpp"
 
 #include "format_error.hpp"
 
 #include <cstddef> //size_t
-#include <type_traits> //is_constant_evaluated
 
 namespace rexy::fmt{
 
@@ -53,8 +54,10 @@ namespace rexy::fmt{
 			//error, already in manual mode
 			REXY_THROW_FORMAT_ERROR("Invalid indexing mode switch");
 		}
-		if(std::is_constant_evaluated() && arg_index >= arg_count){
-			REXY_THROW_FORMAT_ERROR("Missing argument");
+		REXY_if_consteval{
+			if(arg_index >= arg_count){
+				REXY_THROW_FORMAT_ERROR("Missing argument");
+			}
 		}
 		return arg_index++;
 	}
@@ -64,8 +67,10 @@ namespace rexy::fmt{
 			//error, already in automatic mode
 			REXY_THROW_FORMAT_ERROR("Invalid indexing mode switch");
 		}
-		if(std::is_constant_evaluated() && id >= arg_count){
-			REXY_THROW_FORMAT_ERROR("Missing argument");
+		REXY_if_consteval{
+			if(id >= arg_count){
+				REXY_THROW_FORMAT_ERROR("Missing argument");
+			}
 		}
 		arg_index = detail::invalid_arg_index;
 	}
diff --git a/include/rexy/detail/format/specs_handler.hpp b/include/rexy/detail/format/specs_handler.hpp
index 693d62a..26a7717 100644
--- a/include/rexy/detail/format/specs_handler.hpp
+++ b/include/rexy/detail/format/specs_handler.hpp
@@ -19,7 +19,7 @@
 #ifndef REXY_DETAIL_FORMAT_SPECS_HANDLER_HPP
 #define REXY_DETAIL_FORMAT_SPECS_HANDLER_HPP
 
-#include <type_traits> //is_constant_evaluated
+#include "../../compat/if_consteval.hpp"
 
 namespace rexy::fmt::detail{
 
@@ -87,7 +87,7 @@ namespace rexy::fmt::detail{
 
 		constexpr cx_format_specs_handler(ParseCtx& pc, dynamic_format_specs<char_type>& s):
 			dynamic_format_specs_handler<ParseCtx>(pc, s){
-				if(!std::is_constant_evaluated()){
+				REXY_if_not_consteval{
 					throw 0;
 				}
 			}
diff --git a/include/rexy/format.hpp b/include/rexy/format.hpp
index d634ef7..a54deab 100644
--- a/include/rexy/format.hpp
+++ b/include/rexy/format.hpp
@@ -22,6 +22,13 @@
 #include "string.hpp"
 #include "string_view.hpp"
 
+#include "compat/standard.hpp"
+
+#ifndef REXY_STANDARD_CPP20
+	//Maybe I'll make it work someday, but not for now
+	#error "Cannot use formatting library without C++20 support"
+#endif
+
 #include "detail/format/standard_types.hpp"
 #include "detail/format/internal_types.hpp"
 #include "detail/format/arg_store.hpp"
diff --git a/include/rexy/string.hpp b/include/rexy/string.hpp
index 1eb95f5..5006c0f 100644
--- a/include/rexy/string.hpp
+++ b/include/rexy/string.hpp
@@ -26,16 +26,25 @@
 namespace rexy{
 
 	//new allocated string
-	using string = basic_string<char,allocator<char>>;
-	using wstring = basic_string<wchar_t,allocator<wchar_t>>;
+	using string = basic_string<char>;
+	using wstring = basic_string<wchar_t>;
+	using u16string = basic_string<char16_t>;
+	using u32string = basic_string<char32_t>;
+#ifdef __cpp_char8_t
+	using u8string = basic_string<char8_t>;
+#endif
 
 #ifndef LIBREXY_HEADER_ONLY
 	extern template class basic_string<char,allocator<char>>;
 	extern template class basic_string<wchar_t,allocator<wchar_t>>;
 	extern template class basic_string<char16_t,allocator<char16_t>>;
 	extern template class basic_string<char32_t,allocator<char32_t>>;
+#ifdef __cpp_char8_t
+	extern template class basic_string<char8_t,allocator<char8_t>>;
 #endif
 
+#endif //LIBREXY_HEADER_ONLY
+
 }
 
 #ifdef REXY_CX_HASH_HPP
diff --git a/include/rexy/string_base.hpp b/include/rexy/string_base.hpp
index 1ec5924..37ed3d9 100644
--- a/include/rexy/string_base.hpp
+++ b/include/rexy/string_base.hpp
@@ -162,8 +162,7 @@ namespace rexy{
 			}else if(len){
 				set_islong_flag(false);
 				pointer raw = set_short_ptr();
-				if(len)
-					memcpy(raw, data, sizeof(value_type)*len);
+				memcpy(raw, data, sizeof(value_type)*len);
 				raw[len] = 0;
 				set_short_length(len);
 				set_short_capacity(cap);
diff --git a/include/rexy/traits.hpp b/include/rexy/traits.hpp
index fa1d7a3..c8736f6 100644
--- a/include/rexy/traits.hpp
+++ b/include/rexy/traits.hpp
@@ -30,7 +30,7 @@ namespace rexy{
 		static std::true_type check(U*);
 		static std::false_type check(...);
 
-		static constexpr bool value = std::is_same<std::true_type,decltype(check(std::declval<std::decay_t<T>*>()))>::value;
+		static constexpr bool value = decltype(check(std::declval<std::decay_t<T>*>()))::value;
 	};
 
 	template<class T, template<class...> class U>
diff --git a/include/rexy/utility.hpp b/include/rexy/utility.hpp
index 4065b87..eac98fe 100644
--- a/include/rexy/utility.hpp
+++ b/include/rexy/utility.hpp
@@ -26,6 +26,7 @@
 #include <cwchar> //wcslen
 #include <string> //char_traits
 
+#include "compat/if_consteval.hpp"
 #include "rexy.hpp"
 
 namespace rexy{
@@ -91,14 +92,14 @@ namespace rexy{
 			return val > 0 ? val : -val;
 		}
 
-#ifdef __cpp_lib_is_constant_evaluated
+#ifdef REXY_if_constexpr
 		template<class T>
 		constexpr size_t strlen(const T* c)noexcept{
 			return std::char_traits<T>::length(c);
 		}
 		template<class T>
 		constexpr int strcmp(const T* l, const T* r)noexcept{
-			if(!std::is_constant_evaluated()){
+			REXY_if_constexpr{
 				if constexpr(std::is_same_v<std::remove_cvref_t<T>,char>){
 					return std::strcmp(l, r);
 				}else if constexpr(std::is_same_v<std::remove_cvref_t<T>,wchar_t>){
@@ -110,7 +111,7 @@ namespace rexy{
 		}
 		template<class T>
 		constexpr int strncmp(const T* l, const T* r, std::size_t max)noexcept{
-			if(!std::is_constant_evaluated()){
+			REXY_if_constexpr{
 				if constexpr(std::is_same_v<std::remove_cvref_t<T>,char>){
 					return std::strncmp(l, r, max);
 				}else if constexpr (std::is_same_v<std::remove_cvref_t<T>,wchar_t>){
@@ -122,7 +123,7 @@ namespace rexy{
 		}
 		template<class T, class Compare>
 		constexpr int strncmp(const T* l, const T* r, std::size_t max, Compare cmp)noexcept{
-			if(!std::is_constant_evaluated()){
+			REXY_if_constexpr{
 				if constexpr(std::is_same_v<std::remove_cvref_t<T>,char>){
 					return std::strncmp(l, r, max);
 				}else if constexpr (std::is_same_v<std::remove_cvref_t<T>,wchar_t>){
@@ -138,7 +139,7 @@ namespace rexy{
 			return *l - *r;
 		}
 		constexpr void memcpy(void* l, const void* r, size_t n){
-			if(!std::is_constant_evaluated()){
+			REXY_if_constexpr{
 				std::memcpy(l, r, n);
 			}else{
 				char* ld = static_cast<char*>(l);
@@ -149,7 +150,7 @@ namespace rexy{
 			}
 		}
 	}
-#else //__cpp_lib_is_constant_evaluated
+#else // REXY_if_constexpr
 		template<class T>
 		constexpr size_t strlen(const T* c)noexcept{
 			size_t i = 0;
@@ -179,7 +180,7 @@ namespace rexy{
 			}
 		}
 	}
-#endif //__cpp_lib_is_constant_evaluated
+#endif // REXY_if_constexpr
 
 }
 
diff --git a/src/string.cpp b/src/string.cpp
index 4ca26a6..530132f 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -25,5 +25,8 @@ namespace rexy{
 	template class basic_string<wchar_t,allocator<wchar_t>>;
 	template class basic_string<char16_t,allocator<char16_t>>;
 	template class basic_string<char32_t,allocator<char32_t>>;
+#ifdef __cpp_char8_t
+	template class basic_string<char8_t,allocator<char8_t>>;
+#endif
 
 }