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llvm-project/clang/test/Sema/pointer-subtraction.c

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Reland Produce warning for performing pointer arithmetic on a null pointer. Summary: Test and produce warning for subtracting a pointer from null or subtracting null from a pointer. This reland adds the functionality that the warning is no longer reusing an existing warning, it has different wording for C vs C++ to refect the fact that nullptr-nullptr has defined behaviour in C++, it is suppressed when the warning is triggered by a system header and adds -Wnull-pointer-subtraction to allow the warning to be controlled. -Wextra implies -Wnull-pointer-subtraction. Author: Jamie Schmeiser <schmeise@ca.ibm.com> Reviewed By: efriedma (Eli Friedman), nickdesaulniers (Nick Desaulniers) Differential Revision: https://reviews.llvm.org/D98798
2021-07-20 22:12:20 +08:00
// RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wextra -std=c11 -isystem %S/Inputs
// RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wnull-pointer-subtraction -std=c11 -isystem %S/Inputs
// RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wextra -std=c11 -isystem %S/Inputs -Wsystem-headers -DSYSTEM_WARNINGS
// RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -Wnull-pointer-subtraction -std=c11 -isystem %S/Inputs -Wsystem-headers -DSYSTEM_WARNINGS
#include <pointer-subtraction.h>
Use functions with prototypes when appropriate; NFC A significant number of our tests in C accidentally use functions without prototypes. This patch converts the function signatures to have a prototype for the situations where the test is not specific to K&R C declarations. e.g., void func(); becomes void func(void); This is the second batch of tests being updated (there are a significant number of other tests left to be updated).
2022-02-05 04:19:56 +08:00
void a(void) {
Reland Produce warning for performing pointer arithmetic on a null pointer. Summary: Test and produce warning for subtracting a pointer from null or subtracting null from a pointer. This reland adds the functionality that the warning is no longer reusing an existing warning, it has different wording for C vs C++ to refect the fact that nullptr-nullptr has defined behaviour in C++, it is suppressed when the warning is triggered by a system header and adds -Wnull-pointer-subtraction to allow the warning to be controlled. -Wextra implies -Wnull-pointer-subtraction. Author: Jamie Schmeiser <schmeise@ca.ibm.com> Reviewed By: efriedma (Eli Friedman), nickdesaulniers (Nick Desaulniers) Differential Revision: https://reviews.llvm.org/D98798
2021-07-20 22:12:20 +08:00
char *f = (char *)0;
f = (char *)((char *)0 - f); // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
f = (char *)(f - (char *)0); // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
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}}
#ifndef SYSTEM_WARNINGS
SYSTEM_MACRO(f);
#else
SYSTEM_MACRO(f); // expected-warning {{performing pointer subtraction with a null pointer has undefined behavior}}
#endif
}