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/* u_1_24.t: Undefined behaviors on empty argument of macro call. */
/* u.1.24: Empty argument of macro call. */
/*
* Note: Since no argument and one empty argument cannot be distinguished
* syntactically, additional dummy argument may be necessary for an
* intermediate macro to process one empty argument (if possible).
*/
#define ARG( a, dummy) # a
#define EMPTY
#define SHOWN( n) printf( "%s : %d\n", # n, n)
#define SHOWS( s) printf( "%s : %s\n", # s, ARG( s, dummy))
#define add( a, b) (a + b)
#define sub( a, b) (a - b)
#define math( op, a, b) op( a, b)
#define APPEND( a, b) a ## b
/* printf( "%s : %d\n", "math( sub, , y)", ( - y));
or other undefined behavior. */
SHOWN( math( sub, , y));
/* printf( "%s : %s\n", "EMPTY", "");
or other undefined behavior. */
SHOWS( EMPTY);
/* printf( "%s : %s\n", "APPEND( CON, 1)", "CON1"); */
SHOWS( APPEND( CON, 1));
/* printf( "%s : %s\n", "APPEND( CON, )", "CON");
or other undefined behavior. */
SHOWS( APPEND( CON, ));
/* printf( "%s : %s\n", "APPEND( , )", "");
or other undefined behavior. */
SHOWS( APPEND( , ));
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