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