clang/test/SemaCXX/nullptr-arithmetic.cpp

   1 // RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wextra -std=c++11
   2 // RUN: %clang_cc1 %s -fsyntax-only -triple i686-unknown-unknown -verify -pedantic -Wextra -std=c++11
   3 // RUN: %clang_cc1 %s -fsyntax-only -triple x86_64-unknown-unknown -verify -pedantic -Wextra -std=c++11
   4
   5 #include <stdint.h>
   6
   7 void f(intptr_t offset) {
   8   // A zero offset from a nullptr is OK.
   9   char *f = (char*)nullptr + 0;
  10   int *g = (int*)0 + 0;
  11   f = (char*)nullptr - 0;
  12   g = (int*)nullptr - 0;
  13   // adding other values is undefined.
  14   f = (char*)nullptr + offset; // expected-warning {{arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension}}
  15   // Cases that don't match the GNU inttoptr idiom get a different warning.
  16   f = (char*)0 - offset; // expected-warning {{performing pointer arithmetic on a null pointer has undefined behavior if the offset is nonzero}}
  17   g = (int*)0 + offset; // expected-warning {{performing pointer arithmetic on a null pointer has undefined behavior if the offset is nonzero}}
  18 }
  19
  20 // Value-dependent pointer arithmetic should not produce a nullptr warning.
  21 template<char *P>
  22 char* g(intptr_t offset) {
  23   return P + offset;
  24 }
  25
  26 // Value-dependent offsets should not produce a nullptr warning.
  27 template<intptr_t N>
  28 char *h() {
  29   return (char*)nullptr + N;
  30 }