clang/test/Sema/pointer-subtraction.c

   1 // RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wextra -std=c11 -isystem %S/Inputs
   2 // RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wnull-pointer-subtraction -std=c11 -isystem %S/Inputs
   3 // RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wextra -std=c11 -isystem %S/Inputs -Wsystem-headers -DSYSTEM_WARNINGS
   4 // RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wnull-pointer-subtraction -std=c11 -isystem %S/Inputs -Wsystem-headers -DSYSTEM_WARNINGS
   5
   6 #include <pointer-subtraction.h>
   7
   8 void a(void) {
   9   char *f = (char *)0;
  10   f = (char *)((char *)0 - f);         // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
  11   f = (char *)(f - (char *)0);         // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
  12   f = (char *)((char *)0 - (char *)0); // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}} expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
  13
  14   if (1)
  15     f = (char *)((char *)0 - f);         // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
  16   else
  17     f = (char *)((char *)0 - f);
  18
  19   if (0)
  20     f = (char *)((char *)0 - f);
  21   else
  22     f = (char *)((char *)0 - f);         // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
  23
  24 #ifndef SYSTEM_WARNINGS
  25   SYSTEM_MACRO(f);
  26 #else
  27   SYSTEM_MACRO(f); // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
  28 #endif
  29 }