c90-impl-int-2.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

/* Test for implicit int: in C90 only.  Function parameters in old-style
   function definition.
*/
/* Origin: Joseph Myers <[e-mail]> */
/* { dg-do compile } */
/* { dg-options "-std=iso9899:1990 -pedantic-errors" } */

void foo (a) { }