Make C++17 minimum requirement

Signed-off-by: Simon Rozman <simon@rozman.si>

README.md

@@ -1 +1,6 @@
 # stdex - Random stuff that didn't made it into std C++
+
+## Requirements
+
+- MSVC 2019 or later, XCode 13 or later
+- C++17 or later

include/stdex/base64.hpp

@@ -15,20 +15,14 @@
 namespace stdex
 {
 	/// \cond internal
-#if _HAS_CXX17
-	inline
-#endif
-	const char base64_enc_lookup[64] = {
+	inline const char base64_enc_lookup[64] = {
 		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
 		'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
 		'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
 		'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
 	};
 
-#if _HAS_CXX17
-	inline
-#endif
-	const uint8_t base64_dec_lookup[256] = {
+	inline const uint8_t base64_dec_lookup[256] = {
 	/*           0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F  */
 	/* 0 */    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
 	/* 1 */    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

include/stdex/compat.hpp

@@ -172,12 +172,6 @@
 #endif
 #endif
 
-#if _HAS_CXX17
-#define _Constexpr_ constexpr
-#else
-#define _Constexpr_
-#endif
-
 #ifdef _MSC_VER
 #define _Deprecated_(message) __declspec(deprecated(message))
 #else

include/stdex/sgml_unicode.hpp

@@ -13,10 +13,7 @@ namespace stdex
 		wchar_t unicode[3]; ///< Unicode string representation
 	};
 
-#if _HAS_CXX17
-	inline
-#endif
-	const sgml_unicode_pair sgml_unicode[] = {
+	inline const sgml_unicode_pair sgml_unicode[] = {
 		{ "AElig", L"\u00c6" },
 		{ "Aacgr", L"\u0386" },
 		{ "Aacute", L"\u00c1" },
@@ -1554,10 +1551,7 @@ namespace stdex
 		{ "zwnj", L"\u200c" },
 	};
 
-#if _HAS_CXX17
-	inline
-#endif
-	const size_t unicode_sgml[] = {
+	inline const size_t unicode_sgml[] = {
 		0x5b6,
 		0x48d,
 		0x30d,

include/stdex/sys_info.hpp

@@ -48,10 +48,7 @@ namespace stdex
 	///
 	/// System information
 	///
-#if _HAS_CXX17
-	inline
-#endif
-	const struct sys_info_t
+	inline const struct sys_info_t
 	{
 		///
 		/// The platform this process was compiled for

include/stdex/unicode.hpp

@@ -125,7 +125,7 @@ namespace stdex
 			}
 
 #pragma warning(suppress: 4127)
-			if _Constexpr_ (sizeof(T_from) == sizeof(char) && sizeof(T_to) == sizeof(wchar_t)) {
+			if constexpr (sizeof(T_from) == sizeof(char) && sizeof(T_to) == sizeof(wchar_t)) {
 				_Assume_(count_src < INT_MAX || count_src == SIZE_MAX);
 
 				// Try to convert to stack buffer first.
@@ -149,7 +149,7 @@ namespace stdex
 			}
 
 #pragma warning(suppress: 4127)
-			if _Constexpr_ (sizeof(T_from) == sizeof(wchar_t) && sizeof(T_to) == sizeof(char)) {
+			if constexpr (sizeof(T_from) == sizeof(wchar_t) && sizeof(T_to) == sizeof(char)) {
 				_Assume_(count_src < INT_MAX || count_src == SIZE_MAX);
 
 				// Try to convert to stack buffer first.
@@ -173,7 +173,7 @@ namespace stdex
 			}
 
 #pragma warning(suppress: 4127)
-			if _Constexpr_ (sizeof(T_from) == sizeof(char) && sizeof(T_to) == sizeof(char)) {
+			if constexpr (sizeof(T_from) == sizeof(char) && sizeof(T_to) == sizeof(char)) {
 				_Assume_(count_src < INT_MAX || count_src == SIZE_MAX);
 
 				// Try to convert to stack buffer first.