// PR c++/24745 : warnings for NULL constant. // { dg-do compile } // { dg-options "-Wpointer-arith -Wconversion " } #include int foo (void) { if (NULL == 1) return -1; // { dg-warning "NULL used in arithmetic" } if (NULL > NULL) return -1; // { dg-warning "NULL used in arithmetic" } if (NULL < NULL) return -1; // { dg-warning "NULL used in arithmetic" } if (NULL >= 0) return -1; // { dg-warning "NULL used in arithmetic" } if (NULL <= 0) return -1; // { dg-warning "NULL used in arithmetic" } // Adding to the NULL pointer, which has no specific type, should // result in a warning; the type of the resulting expression is // actually "int", not a pointer type. if (NULL + 1) return -1; // { dg-warning "NULL used in arithmetic" } if (1 + NULL) return -1; // { dg-warning "NULL used in arithmetic" } return 0; } int *ip; struct S {}; typedef int S::*SPD; typedef void (S::*SPF)(void); SPD spd; SPF spf; int bar (void) { if (NULL) return -1; if (!NULL) return -1; if (!NULL == 1) return -1; if (NULL || NULL) return -1; if (!NULL && NULL) return -1; if (NULL == NULL) return -1; if (NULL != NULL) return -1; if (NULL == 0) return -1; if (NULL != 0) return -1; // Subtraction of pointers is vaild, so using NULL is OK. if (ip - NULL) return -1; if (NULL - NULL) return -1; // Comparing NULL with a pointer-to-member is OK. if (NULL == spd) return -1; if (spd == NULL) return -1; if (NULL != spd) return -1; if (spd != NULL) return -1; if (NULL == spf) return -1; if (spf == NULL) return -1; if (NULL != spf) return -1; if (spf != NULL) return -1; return 0; }