fix for comparison of utf8_iterator and sentinel

Author: Hana Dusíková

include/ctre/utf8.hpp

@@ -36,6 +36,10 @@ struct utf8_iterator {
 		return lhs.ptr >= lhs.end;
 	}
 
+	constexpr friend bool operator==(sentinel, const utf8_iterator & rhs) {
+		return rhs.ptr >= rhs.end;
+	}
+	
 	constexpr utf8_iterator & operator=(const char8_t * rhs) {
 		ptr = rhs;
 		return *this;

single-header/ctre-unicode.hpp

@@ -2495,6 +2495,10 @@ struct utf8_iterator {
 		return lhs.ptr >= lhs.end;
 	}
 
+	constexpr friend bool operator==(sentinel, const utf8_iterator & rhs) {
+		return rhs.ptr >= rhs.end;
+	}
+	
 	constexpr utf8_iterator & operator=(const char8_t * rhs) {
 		ptr = rhs;
 		return *this;
@@ -4217,8 +4221,14 @@ namespace literals {
 #ifdef __INTEL_COMPILER
 // not enable literals
 #elif defined __GNUC__
-#if not(__GNUC__ == 9)
+#if __GNUC__ < 9
 #define CTRE_ENABLE_LITERALS
+#elif __GNUC__ >= 10
+#if !(__cpp_nontype_template_parameter_class || (__cpp_nontype_template_args >= 201911L)) 
+// newer versions of GCC will give error when trying to use GNU extension
+#else
+#define CTRE_ENABLE_LITERALS
+#endif	
 #endif
 #endif
 

single-header/ctre.hpp

@@ -2492,6 +2492,10 @@ struct utf8_iterator {
 		return lhs.ptr >= lhs.end;
 	}
 
+	constexpr friend bool operator==(sentinel, const utf8_iterator & rhs) {
+		return rhs.ptr >= rhs.end;
+	}
+	
 	constexpr utf8_iterator & operator=(const char8_t * rhs) {
 		ptr = rhs;
 		return *this;
@@ -4214,8 +4218,14 @@ namespace literals {
 #ifdef __INTEL_COMPILER
 // not enable literals
 #elif defined __GNUC__
-#if not(__GNUC__ == 9)
+#if __GNUC__ < 9
 #define CTRE_ENABLE_LITERALS
+#elif __GNUC__ >= 10
+#if !(__cpp_nontype_template_parameter_class || (__cpp_nontype_template_args >= 201911L)) 
+// newer versions of GCC will give error when trying to use GNU extension
+#else
+#define CTRE_ENABLE_LITERALS
+#endif	
 #endif
 #endif