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[libc++] Applied [[nodiscard]] to more Language Support classes #171078

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[libc++] Applied [[nodiscard]] to more Language Support classes #171078

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4 changes: 2 additions & 2 deletions libcxx/include/__new/exceptions.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ class _LIBCPP_EXPORTED_FROM_ABI bad_alloc : public exception {
_LIBCPP_HIDE_FROM_ABI bad_alloc(const bad_alloc&) _NOEXCEPT = default;
_LIBCPP_HIDE_FROM_ABI bad_alloc& operator=(const bad_alloc&) _NOEXCEPT = default;
~bad_alloc() _NOEXCEPT override;
const char* what() const _NOEXCEPT override;
[[__nodiscard__]] const char* what() const _NOEXCEPT override;
};

class _LIBCPP_EXPORTED_FROM_ABI bad_array_new_length : public bad_alloc {
Expand All @@ -41,7 +41,7 @@ class _LIBCPP_EXPORTED_FROM_ABI bad_array_new_length : public bad_alloc {
_LIBCPP_HIDE_FROM_ABI bad_array_new_length(const bad_array_new_length&) _NOEXCEPT = default;
_LIBCPP_HIDE_FROM_ABI bad_array_new_length& operator=(const bad_array_new_length&) _NOEXCEPT = default;
~bad_array_new_length() _NOEXCEPT override;
const char* what() const _NOEXCEPT override;
[[__nodiscard__]] const char* what() const _NOEXCEPT override;
};

#elif defined(_HAS_EXCEPTIONS) && _HAS_EXCEPTIONS == 0 // !_LIBCPP_ABI_VCRUNTIME
Expand Down
8 changes: 5 additions & 3 deletions libcxx/include/typeindex
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Expand Up @@ -86,16 +86,18 @@ public:
}
# endif

_LIBCPP_HIDE_FROM_ABI size_t hash_code() const _NOEXCEPT { return __t_->hash_code(); }
_LIBCPP_HIDE_FROM_ABI const char* name() const _NOEXCEPT { return __t_->name(); }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t hash_code() const _NOEXCEPT { return __t_->hash_code(); }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const char* name() const _NOEXCEPT { return __t_->name(); }
};

template <class _Tp>
struct hash;

template <>
struct hash<type_index> : public __unary_function<type_index, size_t> {
_LIBCPP_HIDE_FROM_ABI size_t operator()(type_index __index) const _NOEXCEPT { return __index.hash_code(); }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t operator()(type_index __index) const _NOEXCEPT {
return __index.hash_code();
}
};

_LIBCPP_END_NAMESPACE_STD
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21 changes: 12 additions & 9 deletions libcxx/include/typeinfo
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Expand Up @@ -95,11 +95,13 @@ class _LIBCPP_EXPORTED_FROM_ABI type_info {
public:
virtual ~type_info();

const char* name() const _NOEXCEPT;
[[__nodiscard__]] const char* name() const _NOEXCEPT;

_LIBCPP_HIDE_FROM_ABI bool before(const type_info& __arg) const _NOEXCEPT { return __compare(__arg) < 0; }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool before(const type_info& __arg) const _NOEXCEPT {
return __compare(__arg) < 0;
}

size_t hash_code() const _NOEXCEPT;
[[__nodiscard__]] size_t hash_code() const _NOEXCEPT;

_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const type_info& __arg) const _NOEXCEPT {
// When evaluated in a constant expression, both type infos simply can't come
Expand Down Expand Up @@ -306,14 +308,15 @@ protected:

public:
virtual ~type_info();
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI const char* name() const _NOEXCEPT {
return __impl::__type_name_to_string(__type_name);
}

_LIBCPP_HIDE_FROM_ABI const char* name() const _NOEXCEPT { return __impl::__type_name_to_string(__type_name); }

_LIBCPP_HIDE_FROM_ABI bool before(const type_info& __arg) const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool before(const type_info& __arg) const _NOEXCEPT {
return __impl::__lt(__type_name, __arg.__type_name);
}

_LIBCPP_HIDE_FROM_ABI size_t hash_code() const _NOEXCEPT { return __impl::__hash(__type_name); }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t hash_code() const _NOEXCEPT { return __impl::__hash(__type_name); }

_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const type_info& __arg) const _NOEXCEPT {
// When evaluated in a constant expression, both type infos simply can't come
Expand All @@ -336,7 +339,7 @@ public:
_LIBCPP_HIDE_FROM_ABI bad_cast(const bad_cast&) _NOEXCEPT = default;
_LIBCPP_HIDE_FROM_ABI bad_cast& operator=(const bad_cast&) _NOEXCEPT = default;
~bad_cast() _NOEXCEPT override;
const char* what() const _NOEXCEPT override;
[[__nodiscard__]] const char* what() const _NOEXCEPT override;
};

class _LIBCPP_EXPORTED_FROM_ABI bad_typeid : public exception {
Expand All @@ -345,7 +348,7 @@ public:
_LIBCPP_HIDE_FROM_ABI bad_typeid(const bad_typeid&) _NOEXCEPT = default;
_LIBCPP_HIDE_FROM_ABI bad_typeid& operator=(const bad_typeid&) _NOEXCEPT = default;
~bad_typeid() _NOEXCEPT override;
const char* what() const _NOEXCEPT override;
[[__nodiscard__]] const char* what() const _NOEXCEPT override;
};

} // namespace std
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50 changes: 36 additions & 14 deletions libcxx/test/libcxx/diagnostics/new.nodiscard.verify.cpp
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Expand Up @@ -6,30 +6,52 @@
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03
// <new>

// check that <array> functions are marked [[nodiscard]]

// clang-format off
// Check that functions are marked [[nodiscard]]

#include <new>

#include "test_macros.h"

void test() {
::operator new(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new(0, std::nothrow); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new[](0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new[](0, std::nothrow); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
{
std::bad_alloc ex;

ex.what(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
{
std::bad_array_new_length ex;

ex.what(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}

{
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new(0);
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new(0, std::nothrow);
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new[](0);
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new[](0, std::nothrow);
#if _LIBCPP_HAS_ALIGNED_ALLOCATION
::operator new(0, std::align_val_t{1}); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new(0, std::align_val_t{1}, std::nothrow); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new[](0, std::align_val_t{1}); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new[](0, std::align_val_t{1}, std::nothrow); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new(0, std::align_val_t{1});
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new(0, std::align_val_t{1}, std::nothrow);
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new[](0, std::align_val_t{1});
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
::operator new[](0, std::align_val_t{1}, std::nothrow);
#endif // _LIBCPP_HAS_ALIGNED_ALLOCATION
}

#if TEST_STD_VER >= 17
int* ptr = nullptr;
std::launder(ptr); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
{
int* ptr = nullptr;

std::launder(ptr); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
#endif
}
33 changes: 33 additions & 0 deletions libcxx/test/libcxx/language.support/nodiscard.verify.cpp
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Expand Up @@ -16,6 +16,8 @@
#include <coroutine>
#include <exception>
#include <initializer_list>
#include <typeinfo>
#include <typeindex>

#include "test_macros.h"

Expand Down Expand Up @@ -126,4 +128,35 @@ void test() {
il.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
#endif

#if !defined(TEST_HAS_NO_RTTI)
{ // <typeindex>
const std::type_index ti(typeid(int));

ti.hash_code(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
ti.name(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

std::hash<std::type_index> hash;

hash(ti); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
#endif

#if !defined(TEST_HAS_NO_RTTI)
{ // <typeinfo>
const std::type_info& ti = typeid(int);

ti.name(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
ti.before(ti); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
ti.hash_code(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

const std::bad_cast bc;

bc.what(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

const std::bad_typeid bt;

bc.what(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
#endif
}
4 changes: 4 additions & 0 deletions libcxx/test/support/test_macros.h
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Expand Up @@ -230,6 +230,10 @@
# define TEST_HAS_NO_ALIGNED_ALLOCATION
#endif

#if !defined(_LIBCPP_ABI_VCRUNTIME)
# define TEST_HAS_NO_ABI_VCRUNTIME
#endif

#if TEST_STD_VER > 17
# define TEST_CONSTINIT constinit
#elif __has_cpp_attribute(clang::require_constant_initialization)
Expand Down
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