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| // RUN: %clang_cc1 -fsyntax-only -verify -Wunused-value %s
// RUN: %clang_cc1 -fsyntax-only -verify -Wunused-value -std=c++98 %s
// RUN: %clang_cc1 -fsyntax-only -verify -Wunused-value -std=c++11 %s
// PR4806
namespace test0 {
class Box {
public:
int i;
volatile int j;
};
void doit() {
// pointer to volatile has side effect (thus no warning)
Box* box = new Box;
box->i; // expected-warning {{expression result unused}}
box->j;
#if __cplusplus <= 199711L
// expected-warning@-2 {{expression result unused}}
#endif
}
}
namespace test1 {
struct Foo {
int i;
bool operator==(const Foo& rhs) {
return i == rhs.i;
}
};
#define NOP(x) (x)
void b(Foo f1, Foo f2) {
NOP(f1 == f2); // expected-warning {{expression result unused}}
}
#undef NOP
}
namespace test2 {
extern "C++" {
namespace std {
template<typename T> struct basic_string {
struct X {};
void method() const {
X* x;
&x[0]; // expected-warning {{expression result unused}}
}
};
typedef basic_string<char> string;
void func(const std::string& str) {
str.method(); // expected-note {{in instantiation of member function}}
}
}
}
}
namespace test3 {
struct Used {
Used();
Used(int);
Used(int, int);
~Used() {}
};
struct __attribute__((warn_unused)) Unused {
Unused();
Unused(int);
Unused(int, int);
~Unused() {}
};
void f() {
Used();
Used(1);
Used(1, 1);
Unused(); // expected-warning {{expression result unused}}
Unused(1); // expected-warning {{expression result unused}}
Unused(1, 1); // expected-warning {{expression result unused}}
#if __cplusplus >= 201103L // C++11 or later
Used({});
Unused({}); // expected-warning {{expression result unused}}
#endif
}
}
namespace std {
struct type_info {};
}
namespace test4 {
struct Good { Good &f(); };
struct Bad { virtual Bad& f(); };
void f() {
int i = 0;
(void)typeid(++i); // expected-warning {{expression with side effects has no effect in an unevaluated context}}
Good g;
(void)typeid(g.f()); // Ok; not a polymorphic use of a glvalue.
// This is a polymorphic use of a glvalue, which results in the typeid being
// evaluated instead of unevaluated.
Bad b;
(void)typeid(b.f()); // expected-warning {{expression with side effects will be evaluated despite being used as an operand to 'typeid'}}
// A dereference of a volatile pointer is a side effecting operation, however
// since it is idiomatic code, and the alternatives induce higher maintenance
// costs, it is allowed.
int * volatile x;
(void)sizeof(*x); // Ok
}
}
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