validation/preprocessor/preprocessor3.c

   1 /*
   2  * Each iteration of the scanning of "SCAN()" re-evaluates the recursive
   3  * B->A->B expansion.
   4  *
   5  * Did I already mention that the C preprocessor language
   6  * is a perverse thing?
   7  */
   8
   9 #define LP (
  10
  11 #define A() B LP )
  12 #define B() A LP )
  13
  14 #define SCAN(x) x
  15
  16 A()                     // B ( )
  17 SCAN( A() )             // A ( )
  18 SCAN(SCAN( A() ))       // B ( )
  19 SCAN(SCAN(SCAN( A() ))) // A ( )
  20 /*
  21  * check-name: Preprocessor #3
  22  * check-description: Sparse used to get this wrong, outputting A third, not B.
  23  * check-command: sparse -E $file
  24  *
  25  * check-output-start
  26
  27 B ( )
  28 A ( )
  29 B ( )
  30 A ( )
  31  * check-output-end
  32  */