[libcxx] [llvm] [libc++] mark `std::expected` as `nodiscard` (PR #130820)
Mohamed Emad via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 20 07:52:15 PDT 2025
https://github.com/hulxv updated https://github.com/llvm/llvm-project/pull/130820
>From 5ef0eb9e5159c6d04eefb24a1afe69a9a3c83e50 Mon Sep 17 00:00:00 2001
From: hulxv <hulxxv at gmail.com>
Date: Tue, 11 Mar 2025 21:30:25 +0200
Subject: [PATCH 1/7] [libc++] mark `std::expected` as `nodiscard` (fix
#130656)
---
libcxx/include/__cxx03/__expected/expected.h | 2 +-
libcxx/include/__expected/expected.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/libcxx/include/__cxx03/__expected/expected.h b/libcxx/include/__cxx03/__expected/expected.h
index 1d54bb9f6edeb..ce9676c68c2dc 100644
--- a/libcxx/include/__cxx03/__expected/expected.h
+++ b/libcxx/include/__cxx03/__expected/expected.h
@@ -58,7 +58,7 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp, class _Err>
-class expected;
+class [[nodiscrad]] expected;
template <class _Tp>
struct __is_std_expected : false_type {};
diff --git a/libcxx/include/__expected/expected.h b/libcxx/include/__expected/expected.h
index 03bbd1623ed5c..8dd32668bcb33 100644
--- a/libcxx/include/__expected/expected.h
+++ b/libcxx/include/__expected/expected.h
@@ -60,7 +60,7 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp, class _Err>
-class expected;
+class [[nodiscard]] expected;
template <class _Tp>
struct __is_std_expected : false_type {};
>From 5943a160fdf8e48a3c2ec20d12000f652e3794b8 Mon Sep 17 00:00:00 2001
From: hulxv <hulxxv at gmail.com>
Date: Tue, 11 Mar 2025 23:13:59 +0200
Subject: [PATCH 2/7] [libcxx] unit test for verifing `nodiscard` for
`std::expected`
---
.../expected.expected/nodiscard.verify.cpp | 31 +++++++++++++++++++
1 file changed, 31 insertions(+)
create mode 100644 libcxx/test/libcxx/utilities/expected/expected.expected/nodiscard.verify.cpp
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/nodiscard.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/nodiscard.verify.cpp
new file mode 100644
index 0000000000000..c8248e7cf32cb
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/nodiscard.verify.cpp
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+// <expected>
+
+// Test that std::expected generates [[nodiscard]] warnings
+
+#include <expected>
+
+std::expected<int, int> returns_expected() {
+ return std::expected<int, int>(5);
+}
+
+std::expected<void, int> returns_expected_void() {
+ return std::expected<void, int>();
+}
+
+void test() {
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ returns_expected();
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ returns_expected_void();
+}
\ No newline at end of file
>From 9c7a735583566ff7343e98272cac39a95cd5b471 Mon Sep 17 00:00:00 2001
From: hulxv <hulxxv at gmail.com>
Date: Wed, 12 Mar 2025 15:25:47 +0200
Subject: [PATCH 3/7] [libcxx] [test] improve `expected/nodiscrard.verify`
---
.../expected/expected.expected/nodiscard.verify.cpp | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/nodiscard.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/nodiscard.verify.cpp
index c8248e7cf32cb..5c3263ec53ca9 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.expected/nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/nodiscard.verify.cpp
@@ -6,11 +6,11 @@
//
//===----------------------------------------------------------------------===//
-// UNSUPPORTED: c++03, c++11, c++14, c++17
+// REQUIRES: std-at-least-c++23
// <expected>
-// Test that std::expected generates [[nodiscard]] warnings
+// Test that ignoring std::expected generates [[nodiscard]] warnings.
#include <expected>
@@ -28,4 +28,4 @@ void test() {
// expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
returns_expected_void();
-}
\ No newline at end of file
+}
>From 6147e4e14396949bd554f67d662a853942caf257 Mon Sep 17 00:00:00 2001
From: hulxv <hulxxv at gmail.com>
Date: Wed, 12 Mar 2025 21:10:17 +0200
Subject: [PATCH 4/7] [libcxx] revert the frozen header
---
libcxx/include/__cxx03/__expected/expected.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libcxx/include/__cxx03/__expected/expected.h b/libcxx/include/__cxx03/__expected/expected.h
index ce9676c68c2dc..1d54bb9f6edeb 100644
--- a/libcxx/include/__cxx03/__expected/expected.h
+++ b/libcxx/include/__cxx03/__expected/expected.h
@@ -58,7 +58,7 @@ _LIBCPP_PUSH_MACROS
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp, class _Err>
-class [[nodiscrad]] expected;
+class expected;
template <class _Tp>
struct __is_std_expected : false_type {};
>From c4b2367518537bccdade75e2f20d055edfeeb47f Mon Sep 17 00:00:00 2001
From: hulxv <hulxxv at gmail.com>
Date: Thu, 13 Mar 2025 18:49:58 +0200
Subject: [PATCH 5/7] [libcxx] add `[[nodiscard]]` to `expected.h`
---
libcxx/include/__expected/expected.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libcxx/include/__expected/expected.h b/libcxx/include/__expected/expected.h
index 8dd32668bcb33..a1179038d69c2 100644
--- a/libcxx/include/__expected/expected.h
+++ b/libcxx/include/__expected/expected.h
@@ -1354,7 +1354,7 @@ class __expected_void_base {
template <class _Tp, class _Err>
requires is_void_v<_Tp>
-class expected<_Tp, _Err> : private __expected_void_base<_Err> {
+class [[nodiscard]] expected<_Tp, _Err> : private __expected_void_base<_Err> {
static_assert(__valid_std_unexpected<_Err>::value,
"[expected.void.general] A program that instantiates expected<T, E> with a E that is not a "
"valid argument for unexpected<E> is ill-formed");
>From 66e1dbc8ddaf6898cb446d71f2b76789a0df8c9a Mon Sep 17 00:00:00 2001
From: hulxv <hulxxv at gmail.com>
Date: Thu, 13 Mar 2025 18:50:28 +0200
Subject: [PATCH 6/7] [libcxx] [test] casting to `void` to avoid `nodiscard`
warnings
---
.../and_then.mandates.verify.cpp | 16 ++++++-------
.../or_else.mandates.verify.cpp | 16 ++++++-------
.../and_then.mandates.verify.cpp | 16 ++++++-------
.../expected.void/or_else.mandates.verify.cpp | 24 +++++++++----------
4 files changed, 36 insertions(+), 36 deletions(-)
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
index c46ab633295c1..7c95fc19cd693 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
@@ -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{{.*}}}}
@@ -60,7 +60,7 @@ 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}}
}
}
@@ -70,7 +70,7 @@ 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{{.*}}}}
@@ -79,7 +79,7 @@ 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}}
}
@@ -90,7 +90,7 @@ 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{{.*}}}}
@@ -99,7 +99,7 @@ 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}}
}
}
@@ -109,7 +109,7 @@ 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{{.*}}}}
@@ -118,7 +118,7 @@ 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}}
}
}
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
index af1fa53307960..8064463977e48 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
@@ -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{{.*}}}}
@@ -60,7 +60,7 @@ 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}}
}
}
@@ -70,7 +70,7 @@ 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{{.*}}}}
@@ -79,7 +79,7 @@ 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}}
}
}
@@ -89,7 +89,7 @@ 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{{.*}}}}
@@ -98,7 +98,7 @@ 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}}
}
}
@@ -108,7 +108,7 @@ 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{{.*}}}}
@@ -117,7 +117,7 @@ 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}}
}
}
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp
index e1a7ec5ff4d72..92713f0f78148 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp
@@ -51,7 +51,7 @@ void test() {
// U is not a specialization of std::expected
{
std::expected<void, int> f1;
- f1.and_then(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
+ (void)f1.and_then(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() 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{{.*}}}}
@@ -60,7 +60,7 @@ void test() {
// !std::is_same_v<U:error_type, E>
{
std::expected<void, int> f1;
- f1.and_then(lval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
+ (void)f1.and_then(lval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() must have the same error_type as this expected}}
}
}
@@ -70,7 +70,7 @@ void test() {
// U is not a specialization of std::expected
{
const std::expected<void, int> f1;
- f1.and_then(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
+ (void)f1.and_then(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() 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{{.*}}}}
@@ -79,7 +79,7 @@ void test() {
// !std::is_same_v<U:error_type, E>
{
const std::expected<void, int> f1;
- f1.and_then(clval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
+ (void)f1.and_then(clval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() must have the same error_type as this expected}}
}
}
@@ -89,7 +89,7 @@ void test() {
// U is not a specialization of std::expected
{
std::expected<void, int> f1;
- std::move(f1).and_then(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
+ (void)std::move(f1).and_then(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() 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{{.*}}}}
@@ -98,7 +98,7 @@ void test() {
// !std::is_same_v<U:error_type, E>
{
std::expected<void, int> f1;
- std::move(f1).and_then(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' 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<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() must have the same error_type as this expected}}
}
}
@@ -108,7 +108,7 @@ void test() {
// U is not a specialization of std::expected
{
const std::expected<void, int> f1;
- std::move(f1).and_then(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
+ (void)std::move(f1).and_then(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() 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{{.*}}}}
@@ -117,7 +117,7 @@ void test() {
// !std::is_same_v<U:error_type, E>
{
const std::expected<void, int> f1;
- std::move(f1).and_then(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' 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<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() must have the same error_type as this expected}}
}
}
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp
index 3046d09d6af55..244f82134daf5 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp
@@ -51,7 +51,7 @@ void test() {
// G is not a specialization of std::expected
{
std::expected<void, int> f1(std::unexpected<int>(1));
- f1.or_else(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, 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<void, 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}}
}
@@ -59,7 +59,7 @@ void test() {
// !std::is_same_v<G:value_type, T>
{
std::expected<void, 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<void, 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<void, 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}}
}
}
@@ -69,7 +69,7 @@ void test() {
// G is not a specialization of std::expected
{
const std::expected<void, int> f1(std::unexpected<int>(1));
- f1.or_else(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, 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<void, 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}}
}
@@ -77,7 +77,7 @@ void test() {
// !std::is_same_v<G:value_type, T>
{
const std::expected<void, 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<void, 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<void, 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}}
}
}
@@ -87,16 +87,16 @@ void test() {
// G is not a specialization of std::expected
{
std::expected<void, 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<void, 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}}
+ (void)std::move(f1).or_else(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<int (&)(int &&)>' requested here}}
+ // expected-error-re@*:* {{static assertion failed {{.*}}The result of f((void)std::move(error())) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
}
// !std::is_same_v<G:value_type, T>
{
std::expected<void, 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<void, 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}}
+ (void)std::move(f1).or_else(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &&)>' requested here}}
+ // expected-error-re@*:* {{static assertion failed {{.*}}The result of f((void)std::move(error())) must have the same value_type as this expected}}
}
}
@@ -105,16 +105,16 @@ void test() {
// G is not a specialization of std::expected
{
const std::expected<void, 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<void, 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}}
+ (void)std::move(f1).or_else(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<int (&)(const int &&)>' requested here}}
+ // expected-error-re@*:* {{static assertion failed {{.*}}The result of f((void)std::move(error())) must be a specialization of std::expected}}
// expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
}
// !std::is_same_v<G:value_type, T>
{
const std::expected<void, 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<void, 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}}
+ (void)std::move(f1).or_else(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &&)>' requested here}}
+ // expected-error-re@*:* {{static assertion failed {{.*}}The result of f((void)std::move(error())) must have the same value_type as this expected}}
}
}
}
>From 57dc1935811201a19cf713bb658bdb1e44ccd06a Mon Sep 17 00:00:00 2001
From: hulxv <hulxxv at gmail.com>
Date: Thu, 20 Mar 2025 16:51:29 +0200
Subject: [PATCH 7/7] [libcxx] add `nodiscard` test for monadic operations
---
.gitignore | 3 +++
.../expected.expected/and_then.mandates.verify.cpp | 8 ++++++++
.../expected.expected/or_else.mandates.verify.cpp | 8 ++++++++
.../expected/expected.void/and_then.mandates.verify.cpp | 8 ++++++++
.../expected/expected.void/or_else.mandates.verify.cpp | 9 +++++++++
5 files changed, 36 insertions(+)
diff --git a/.gitignore b/.gitignore
index a84268a7f6863..449f0970869a0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -73,3 +73,6 @@ pythonenv*
/clang/utils/analyzer/projects/*/RefScanBuildResults
# automodapi puts generated documentation files here.
/lldb/docs/python_api/
+
+
+.build*
\ No newline at end of file
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
index 7c95fc19cd693..456ac2f0630ed 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
@@ -122,5 +122,13 @@ void test() {
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(value())) must have the same error_type as this expected}}
}
}
+
+ // Test nodiscard
+ {
+ const std::expected<int, int> f1(std::unexpected<int>(1));
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ f1.and_then([](int&){ return 1; });
+ }
}
// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
index 8064463977e48..6c29b3eedbf2a 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
@@ -121,5 +121,13 @@ void test() {
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(error())) must have the same value_type as this expected}}
}
}
+
+ // Test nodiscard
+ {
+ const std::expected<int, int> f1(std::unexpected<int>(1));
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ f1.or_else([](int&){ return 1; });
+ }
}
// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp
index 92713f0f78148..139fe0f2013d6 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp
@@ -121,5 +121,13 @@ void test() {
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f() must have the same error_type as this expected}}
}
}
+
+ // Test nodiscard
+ {
+ const std::expected<int, int> f1(std::unexpected<int>(1));
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ f1.and_then([](int&){ return 1; });
+ }
}
// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp
index 244f82134daf5..826044311bca3 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp
@@ -117,5 +117,14 @@ void test() {
// expected-error-re@*:* {{static assertion failed {{.*}}The result of f((void)std::move(error())) must have the same value_type as this expected}}
}
}
+
+
+ // Test nodiscard
+ {
+ const std::expected<int, int> f1(std::unexpected<int>(1));
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ f1.or_else([](int&){ return 1; });
+ }
}
// clang-format on
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