use standard [[ noreturn ]] attribute

add ENSURE macro

tools/quake3/common/cmdlib.h

@@ -171,11 +171,11 @@ void ExpandWildcards( int *argc, char ***argv );
 
 double I_FloatTime( void );
 
-void    Error( const char *error, ... )
-#ifdef __GNUC__
-__attribute__( ( noreturn ) )
-#endif
-;
+[[ noreturn ]] void Error( const char *error, ... );
+#define ENSURE( condition ) \
+	(void) \
+	( (!!( condition )) || \
+	(Error( "%s:%u:%s: Condition '%s' failed.", __FILE__, __LINE__, __func__, #condition ), 0) )
 
 FILE    *SafeOpenWrite( const char *filename, const char *mode = "wb" );
 FILE    *SafeOpenRead( const char *filename, const char *mode = "rb" );

tools/quake3/q3map2/games.cpp

@@ -29,6 +29,7 @@
 #include "games.h"
 #include "bspfile_ibsp.h"
 #include "bspfile_rbsp.h"
+#include "cmdlib.h"
 
 struct game_default : game_t
 {
@@ -521,6 +522,7 @@ struct game_ef : game_default
 		homeBasePath = ".ef";
 		magic = "elite";
 		/* overwrite "ladder" entry; note: magic number */
+		ENSURE( strEqual( surfaceParms[31].name, "ladder" ) );
 		surfaceParms[31] =
 		{ "ladder",         E_CONT_LADDER,              Q_CONT_SOLID,               Q_SURF_LADDER,              0,                          C_DETAIL | C_TRANSLUCENT,   C_SOLID };
 		surfaceParms.insert( surfaceParms.end(), {