// RUN: %check_clang_tidy %s bugprone-unused-return-value %t -- \
// RUN: --config="{CheckOptions: {bugprone-unused-return-value.AllowCastToVoid: true}}" -- -fexceptions
namespace std {
struct future {};
enum class launch {
async,
deferred
};
template <typename Function, typename... Args>
future async(Function &&, Args &&...);
template <typename Function, typename... Args>
future async(launch, Function &&, Args &&...);
template <typename ForwardIt, typename T>
ForwardIt remove(ForwardIt, ForwardIt, const T &);
template <typename ForwardIt, typename UnaryPredicate>
ForwardIt remove_if(ForwardIt, ForwardIt, UnaryPredicate);
template <typename ForwardIt>
ForwardIt unique(ForwardIt, ForwardIt);
template <typename T>
struct default_delete;
template <typename T, typename Deleter = std::default_delete<T>>
struct unique_ptr {
unique_ptr();
unique_ptr(unique_ptr const&);
unique_ptr(unique_ptr &&);
unique_ptr& operator=(unique_ptr const&);
unique_ptr& operator=(unique_ptr &&);
T *release() noexcept;
};
template <typename T>
struct char_traits;
template <typename T>
struct allocator;
template <typename CharT,
typename Traits = char_traits<CharT>,
typename Allocator = allocator<CharT>>
struct basic_string {
bool empty() const;
};
typedef basic_string<char> string;
template <typename T, typename Allocator = std::allocator<T>>
struct vector {
bool empty() const noexcept;
};
class error_code {
};
// the check should be able to match std lib calls even if the functions are
// declared inside inline namespaces
inline namespace v1 {
template <typename T>
T *launder(T *);
} // namespace v1
} // namespace std
struct Foo {
void f();
};
int increment(int i) {
return i + 1;
}
void useFuture(const std::future &fut);
std::error_code errorFunc() {
return std::error_code();
}
void warning() {
std::async(increment, 42);
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
std::async(std::launch::async, increment, 42);
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
Foo F;
std::launder(&F);
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
std::remove_if(nullptr, nullptr, nullptr);
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
std::unique(nullptr, nullptr);
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
std::unique_ptr<Foo> UPtr;
UPtr.release();
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
std::string Str;
Str.empty();
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
(int)Str.empty();
// CHECK-MESSAGES: [[@LINE-1]]:8: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:8: note: cast the expression to void to silence this warning
std::vector<Foo> Vec;
Vec.empty();
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
// test discarding return values inside different kinds of statements
auto Lambda = [] { std::remove(nullptr, nullptr, 1); };
// CHECK-MESSAGES: [[@LINE-1]]:22: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:22: note: cast the expression to void to silence this warning
if (true)
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
else if (true)
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
else
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
while (true)
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
do
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
while (true);
for (;;)
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
for (std::remove(nullptr, nullptr, 1);;)
// CHECK-MESSAGES: [[@LINE-1]]:8: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:8: note: cast the expression to void to silence this warning
;
for (;; std::remove(nullptr, nullptr, 1))
// CHECK-MESSAGES: [[@LINE-1]]:11: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:11: note: cast the expression to void to silence this warning
;
for (auto C : "foo")
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
switch (1) {
case 1:
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
break;
default:
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
break;
}
try {
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
} catch (...) {
std::remove(nullptr, nullptr, 1);
// CHECK-MESSAGES: [[@LINE-1]]:5: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:5: note: cast the expression to void to silence this warning
}
errorFunc();
// CHECK-MESSAGES: [[@LINE-1]]:3: warning: the value returned by this function should not be disregarded; neglecting it may lead to errors
// CHECK-MESSAGES: [[@LINE-2]]:3: note: cast the expression to void to silence this warning
}
void noWarning() {
auto AsyncRetval1 = std::async(increment, 42);
auto AsyncRetval2 = std::async(std::launch::async, increment, 42);
Foo FNoWarning;
auto LaunderRetval = std::launder(&FNoWarning);
auto RemoveRetval = std::remove(nullptr, nullptr, 1);
auto RemoveIfRetval = std::remove_if(nullptr, nullptr, nullptr);
auto UniqueRetval = std::unique(nullptr, nullptr);
std::unique_ptr<Foo> UPtrNoWarning;
auto ReleaseRetval = UPtrNoWarning.release();
std::string StrNoWarning;
auto StrEmptyRetval = StrNoWarning.empty();
std::vector<Foo> VecNoWarning;
auto VecEmptyRetval = VecNoWarning.empty();
(void) errorFunc();
// test using the return value in different kinds of expressions
useFuture(std::async(increment, 42));
std::launder(&FNoWarning)->f();
delete std::launder(&FNoWarning);
if (std::launder(&FNoWarning))
;
for (; std::launder(&FNoWarning);)
;
while (std::launder(&FNoWarning))
;
do
;
while (std::launder(&FNoWarning));
switch (std::unique(1, 1))
;
// cast to void should allow ignoring the return value
(void)std::async(increment, 42);
// test discarding return value of functions that are not configured to be checked
increment(1);
// test that the check is disabled inside GNU statement expressions
({ std::async(increment, 42); });
auto StmtExprRetval = ({ std::async(increment, 42); });
}
namespace gh84314 {
extern std::unique_ptr<int> alloc();
void f1(std::unique_ptr<int> &foo) {
foo = alloc();
}
} // namespace gh84314
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