/* No escape */
#define MESSAGE1 "@var1@"

/* Single escape means no replace */
#define MESSAGE2 "\@var1@"

/* Replace pairs of escapes before '@' or '\@' with escape characters
 * (note we have to double number of pairs due to C string escaping)
 */
#define MESSAGE3 "\\\\@var1@"

/* Pairs of escapes and then single escape to avoid replace */
#define MESSAGE4 "\\\\\@var1@"

/* Check escaped variable does not overlap following variable */
#define MESSAGE5 "\@var1@var2@"

/* Check escape character outside variables */
#define MESSAGE6 "\\ @ \@ \\\\@ \\\\\@"