1  /* { dg-do preprocess } */
       2  /* { dg-options "-std=gnu99" { target c } } */
       3  /* { dg-options "-std=c++20" { target c++ } } */
       4  
       5  #define a ""
       6  #define b(...) a ## #__VA_OPT__(1)	/* { dg-error "pasting \"a\" and \"\"\"\" does not give a valid preprocessing token" } */
       7  #define c(...) a ## #__VA_OPT__(1)	/* { dg-error "pasting \"a\" and \"\"1\"\" does not give a valid preprocessing token" } */
       8  #define d(...) #__VA_OPT__(1) ## !
       9  #define e(...) #__VA_OPT__(1) ## !
      10  #define f(...) #__VA_OPT__(. ## !)
      11  #define g(...) #__VA_OPT__(. ## !)
      12  b()
      13  c(1)
      14  d(   )		/* { dg-error "pasting \"\"\"\" and \"!\" does not give a valid preprocessing token" } */
      15  e(  1 )		/* { dg-error "pasting \"\"1\"\" and \"!\" does not give a valid preprocessing token" } */
      16  f()
      17  g(0)		/* { dg-error "pasting \".\" and \"!\" does not give a valid preprocessing token" } */