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Merged
Zingam merged 5 commits into from
Dec 14, 2025
Merged

[libc++][expected] Applied [[nodiscard]] #170245

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ef8aa11
[libc++][expected] Applied `[[nodiscard]]`
H-G-Hristov Dec 2, 2025
e735741
Simplified tests
H-G-Hristov Dec 2, 2025
60c468a
Adressed review comments
H-G-Hristov Dec 12, 2025
969f5b8
Addressed review comments
H-G-Hristov Dec 14, 2025
827b100
Merge branch 'main' into hgh/libcxx/nodiscard-to-expected
H-G-Hristov Dec 14, 2025
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14 changes: 8 additions & 6 deletions libcxx/include/__expected/bad_expected_access.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,9 +43,11 @@ class _LIBCPP_EXPORTED_FROM_ABI bad_expected_access<void> : public exception {

public:
# if _LIBCPP_AVAILABILITY_HAS_BAD_EXPECTED_ACCESS_KEY_FUNCTION
const char* what() const noexcept override;
[[nodiscard]] const char* what() const noexcept override;
# else
_LIBCPP_HIDE_FROM_ABI_VIRTUAL const char* what() const noexcept override { return "bad access to std::expected"; }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI_VIRTUAL const char* what() const noexcept override {
return "bad access to std::expected";
}
# endif
};
_LIBCPP_DIAGNOSTIC_POP
Expand All @@ -55,10 +57,10 @@ class bad_expected_access : public bad_expected_access<void> {
public:
_LIBCPP_HIDE_FROM_ABI explicit bad_expected_access(_Err __e) : __unex_(std::move(__e)) {}

_LIBCPP_HIDE_FROM_ABI _Err& error() & noexcept { return __unex_; }
_LIBCPP_HIDE_FROM_ABI const _Err& error() const& noexcept { return __unex_; }
_LIBCPP_HIDE_FROM_ABI _Err&& error() && noexcept { return std::move(__unex_); }
_LIBCPP_HIDE_FROM_ABI const _Err&& error() const&& noexcept { return std::move(__unex_); }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI _Err& error() & noexcept { return __unex_; }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI const _Err& error() const& noexcept { return __unex_; }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI _Err&& error() && noexcept { return std::move(__unex_); }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI const _Err&& error() const&& noexcept { return std::move(__unex_); }

private:
_Err __unex_;
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112 changes: 56 additions & 56 deletions libcxx/include/__expected/expected.h
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8 changes: 4 additions & 4 deletions libcxx/include/__expected/unexpected.h
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Expand Up @@ -89,10 +89,10 @@ class unexpected {
_LIBCPP_HIDE_FROM_ABI constexpr unexpected& operator=(const unexpected&) = default;
_LIBCPP_HIDE_FROM_ABI constexpr unexpected& operator=(unexpected&&) = default;

_LIBCPP_HIDE_FROM_ABI constexpr const _Err& error() const& noexcept { return __unex_; }
_LIBCPP_HIDE_FROM_ABI constexpr _Err& error() & noexcept { return __unex_; }
_LIBCPP_HIDE_FROM_ABI constexpr const _Err&& error() const&& noexcept { return std::move(__unex_); }
_LIBCPP_HIDE_FROM_ABI constexpr _Err&& error() && noexcept { return std::move(__unex_); }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Err& error() const& noexcept { return __unex_; }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Err& error() & noexcept { return __unex_; }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Err&& error() const&& noexcept { return std::move(__unex_); }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Err&& error() && noexcept { return std::move(__unex_); }

_LIBCPP_HIDE_FROM_ABI constexpr void swap(unexpected& __other) noexcept(is_nothrow_swappable_v<_Err>) {
static_assert(is_swappable_v<_Err>, "unexpected::swap requires is_swappable_v<E> to be true");
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16 changes: 8 additions & 8 deletions libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
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Expand Up @@ -51,7 +51,7 @@ void test() {
// U is not a specialization of std::expected
{
std::expected<int, int> f1(1);
f1.and_then(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(int &)>' requested here}}
(void)f1.and_then(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(int &)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(value()) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
// expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
Expand All @@ -61,7 +61,7 @@ void test() {
// !std::is_same_v<U:error_type, E>
{
std::expected<int, int> f1(1);
f1.and_then(lval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(int &)>' requested here}}
(void)f1.and_then(lval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(int &)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(value()) must have the same error_type as this expected}}
}
}
Expand All @@ -71,7 +71,7 @@ void test() {
// U is not a specialization of std::expected
{
const std::expected<int, int> f1(1);
f1.and_then(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(const int &)>' requested here}}
(void)f1.and_then(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(const int &)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(value()) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
// expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
Expand All @@ -81,7 +81,7 @@ void test() {
// !std::is_same_v<U:error_type, E>
{
const std::expected<int, int> f1(1);
f1.and_then(clval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(const int &)>' requested here}}
(void)f1.and_then(clval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(const int &)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(value()) must have the same error_type as this expected}}

}
Expand All @@ -92,7 +92,7 @@ void test() {
// U is not a specialization of std::expected
{
std::expected<int, int> f1(1);
std::move(f1).and_then(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(int &&)>' requested here}}
(void)std::move(f1).and_then(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(int &&)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(value())) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
// expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
Expand All @@ -102,7 +102,7 @@ void test() {
// !std::is_same_v<U:error_type, E>
{
std::expected<int, int> f1(1);
std::move(f1).and_then(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(int &&)>' requested here}}
(void)std::move(f1).and_then(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(int &&)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(value())) must have the same error_type as this expected}}
}
}
Expand All @@ -112,7 +112,7 @@ void test() {
// U is not a specialization of std::expected
{
const std::expected<int, int> f1(1);
std::move(f1).and_then(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(const int &&)>' requested here}}
(void)std::move(f1).and_then(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(const int &&)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(value())) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
// expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
Expand All @@ -122,7 +122,7 @@ void test() {
// !std::is_same_v<U:error_type, E>
{
const std::expected<int, int> f1(1);
std::move(f1).and_then(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(const int &&)>' requested here}}
(void)std::move(f1).and_then(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(const int &&)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(value())) must have the same error_type as this expected}}
}
}
Expand Down
8 changes: 4 additions & 4 deletions libcxx/test/libcxx/utilities/expected/expected.expected/error_or.mandates.verify.cpp
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Expand Up @@ -36,7 +36,7 @@ void test() {
// !is_copy_constructible_v<G>,
{
const std::expected<int, NonCopyable> f1(std::unexpect, 0);
f1.error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NonCopyable>::error_or<int>' requested here}}
(void)f1.error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NonCopyable>::error_or<int>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}error_type has to be copy constructible}}
// expected-error-re@*:* {{call to deleted constructor of{{.*}}}}
}
Expand All @@ -45,7 +45,7 @@ void test() {
// !is_convertible_v<U, T>
{
const std::expected<int, NotConvertibleFromInt> f1(std::unexpect, NotConvertibleFromInt{});
f1.error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NotConvertibleFromInt>::error_or<int>' requested here}}
(void)f1.error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NotConvertibleFromInt>::error_or<int>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}argument has to be convertible to error_type}}
// expected-error-re@*:* {{no viable conversion from returned value of type{{.*}}}}

Expand All @@ -55,7 +55,7 @@ void test() {
// !is_move_constructible_v<T>,
{
std::expected<int, NonMovable> f1(std::unexpect, 0);
std::move(f1).error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NonMovable>::error_or<int>' requested here}}
(void)std::move(f1).error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NonMovable>::error_or<int>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}error_type has to be move constructible}}
// expected-error-re@*:* {{call to deleted constructor of{{.*}}}}
}
Expand All @@ -64,7 +64,7 @@ void test() {
// !is_convertible_v<U, T>
{
std::expected<int, NotConvertibleFromInt> f1(std::unexpect, NotConvertibleFromInt{});
std::move(f1).error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NotConvertibleFromInt>::error_or<int>' requested here}}
(void)std::move(f1).error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NotConvertibleFromInt>::error_or<int>' requested here}}
//expected-error-re@*:* {{static assertion failed {{.*}}argument has to be convertible to error_type}}
// expected-error-re@*:* {{no viable conversion from returned value of type{{.*}}}}
}
Expand Down
16 changes: 8 additions & 8 deletions libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
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Expand Up @@ -51,7 +51,7 @@ void test() {
// G is not a specialization of std::expected
{
std::expected<int, int> f1(std::unexpected<int>(1));
f1.or_else(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(int &)>' requested here}}
(void)f1.or_else(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(int &)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(error()) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
// expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
Expand All @@ -61,7 +61,7 @@ void test() {
// !std::is_same_v<G:value_type, T>
{
std::expected<int, int> f1(std::unexpected<int>(1));
f1.or_else(lval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &)>' requested here}}
(void)f1.or_else(lval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(error()) must have the same value_type as this expected}}
}
}
Expand All @@ -71,7 +71,7 @@ void test() {
// G is not a specialization of std::expected
{
const std::expected<int, int> f1(std::unexpected<int>(1));
f1.or_else(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(const int &)>' requested here}}
(void)f1.or_else(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(const int &)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(error()) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
// expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
Expand All @@ -81,7 +81,7 @@ void test() {
// !std::is_same_v<G:value_type, T>
{
const std::expected<int, int> f1(std::unexpected<int>(1));
f1.or_else(clval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &)>' requested here}}
(void)f1.or_else(clval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(error()) must have the same value_type as this expected}}
}
}
Expand All @@ -91,7 +91,7 @@ void test() {
// G is not a specialization of std::expected
{
std::expected<int, int> f1(std::unexpected<int>(1));
std::move(f1).or_else(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(int &&)>' requested here}}
(void)std::move(f1).or_else(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(int &&)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(error())) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
// expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
Expand All @@ -101,7 +101,7 @@ void test() {
// !std::is_same_v<G:value_type, T>
{
std::expected<int, int> f1(std::unexpected<int>(1));
std::move(f1).or_else(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &&)>' requested here}}
(void)std::move(f1).or_else(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &&)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(error())) must have the same value_type as this expected}}
}
}
Expand All @@ -111,7 +111,7 @@ void test() {
// G is not a specialization of std::expected
{
const std::expected<int, int> f1(std::unexpected<int>(1));
std::move(f1).or_else(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(const int &&)>' requested here}}
(void)std::move(f1).or_else(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(const int &&)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(error())) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
// expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
Expand All @@ -121,7 +121,7 @@ void test() {
// !std::is_same_v<G:value_type, T>
{
const std::expected<int, int> f1(std::unexpected<int>(1));
std::move(f1).or_else(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &&)>' requested here}}
(void)std::move(f1).or_else(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &&)>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(error())) must have the same value_type as this expected}}
}
}
Expand Down
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