Tested x86_64-linux. Reviews invited.
-- >8 --
libstdc++-v3/ChangeLog:
* include/bits/stl_bvector.h (vector<bool, A>::at): Add
nodiscard.
* include/bits/stl_vector.h (vector<T, A>::at): Likewise.
(operator==, operator<=>, operator<, operator!=, operator>)
(operator<=, operator>=): Add nodiscard.
* testsuite/23_containers/vector/nodiscard.cc: New test.
---
libstdc++-v3/include/bits/stl_bvector.h | 4 +-
libstdc++-v3/include/bits/stl_vector.h | 18 +--
.../23_containers/vector/nodiscard.cc | 153 ++++++++++++++++++
3 files changed, 164 insertions(+), 11 deletions(-)
create mode 100644 libstdc++-v3/testsuite/23_containers/vector/nodiscard.cc
diff --git a/libstdc++-v3/include/bits/stl_bvector.h
b/libstdc++-v3/include/bits/stl_bvector.h
index aa5644b4a0e..2c8b892b07a 100644
--- a/libstdc++-v3/include/bits/stl_bvector.h
+++ b/libstdc++-v3/include/bits/stl_bvector.h
@@ -1101,7 +1101,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
}
public:
- _GLIBCXX20_CONSTEXPR
+ _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
reference
at(size_type __n)
{
@@ -1109,7 +1109,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
return (*this)[__n];
}
- _GLIBCXX20_CONSTEXPR
+ _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
const_reference
at(size_type __n) const
{
diff --git a/libstdc++-v3/include/bits/stl_vector.h
b/libstdc++-v3/include/bits/stl_vector.h
index 6a9543eefce..a8d387f40a1 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -1172,7 +1172,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
* is first checked that it is in the range of the vector. The
* function throws out_of_range if the check fails.
*/
- _GLIBCXX20_CONSTEXPR
+ _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
reference
at(size_type __n)
{
@@ -1191,7 +1191,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
* is first checked that it is in the range of the vector. The
* function throws out_of_range if the check fails.
*/
- _GLIBCXX20_CONSTEXPR
+ _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
const_reference
at(size_type __n) const
{
@@ -2042,7 +2042,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
* and if corresponding elements compare equal.
*/
template<typename _Tp, typename _Alloc>
- _GLIBCXX20_CONSTEXPR
+ _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
inline bool
operator==(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{ return (__x.size() == __y.size()
@@ -2061,7 +2061,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
* `<` and `>=` etc.
*/
template<typename _Tp, typename _Alloc>
- _GLIBCXX20_CONSTEXPR
+ [[nodiscard]] _GLIBCXX20_CONSTEXPR
inline __detail::__synth3way_t<_Tp>
operator<=>(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{
@@ -2082,32 +2082,32 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
* See std::lexicographical_compare() for how the determination is made.
*/
template<typename _Tp, typename _Alloc>
- inline bool
+ _GLIBCXX_NODISCARD inline bool
operator<(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{ return std::lexicographical_compare(__x.begin(), __x.end(),
__y.begin(), __y.end()); }
/// Based on operator==
template<typename _Tp, typename _Alloc>
- inline bool
+ _GLIBCXX_NODISCARD inline bool
operator!=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{ return !(__x == __y); }
/// Based on operator<
template<typename _Tp, typename _Alloc>
- inline bool
+ _GLIBCXX_NODISCARD inline bool
operator>(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{ return __y < __x; }
/// Based on operator<
template<typename _Tp, typename _Alloc>
- inline bool
+ _GLIBCXX_NODISCARD inline bool
operator<=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{ return !(__y < __x); }
/// Based on operator<
template<typename _Tp, typename _Alloc>
- inline bool
+ _GLIBCXX_NODISCARD inline bool
operator>=(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
{ return !(__x < __y); }
#endif // three-way comparison
diff --git a/libstdc++-v3/testsuite/23_containers/vector/nodiscard.cc
b/libstdc++-v3/testsuite/23_containers/vector/nodiscard.cc
new file mode 100644
index 00000000000..3b5480d16d4
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/vector/nodiscard.cc
@@ -0,0 +1,153 @@
+// { dg-do compile { target c++17 } }
+
+#include <vector>
+
+void
+test_observers(std::vector<int> v)
+{
+ v.size(); // { dg-warning "ignoring return value" }
+ v.capacity(); // { dg-warning "ignoring return value" }
+ v.empty(); // { dg-warning "ignoring return value" }
+}
+
+void
+test_element_access(std::vector<float> v)
+{
+ v.front(); // { dg-warning "ignoring return value" }
+ v.back(); // { dg-warning "ignoring return value" }
+ v[1]; // { dg-warning "ignoring return value" }
+ v.at(1); // { dg-warning "ignoring return value" }
+ v.data(); // { dg-warning "ignoring return value" }
+ const auto& cv = v;
+ cv[1]; // { dg-warning "ignoring return value" }
+ cv.at(1); // { dg-warning "ignoring return value" }
+ cv.data(); // { dg-warning "ignoring return value" }
+}
+
+void
+test_rel_ops(std::vector<char> v)
+{
+ v == v; // { dg-warning "ignoring return value" }
+ v != v; // { dg-warning "ignoring return value" "PR c++/114104" { target
c++17_down } }
+ v < v; // { dg-warning "ignoring return value" }
+ v > v; // { dg-warning "ignoring return value" }
+ v <= v; // { dg-warning "ignoring return value" }
+ v >= v; // { dg-warning "ignoring return value" }
+}
+
+struct S { };
+
+void
+test_iterators(std::vector<S> v)
+{
+ v.begin(); // { dg-warning "ignoring return value" }
+ v.end(); // { dg-warning "ignoring return value" }
+ v.rbegin(); // { dg-warning "ignoring return value" }
+ v.rend(); // { dg-warning "ignoring return value" }
+ const auto& cv = v;
+ cv.begin(); // { dg-warning "ignoring return value" }
+ cv.end(); // { dg-warning "ignoring return value" }
+ cv.rbegin(); // { dg-warning "ignoring return value" }
+ cv.rend(); // { dg-warning "ignoring return value" }
+
+ v.cbegin(); // { dg-warning "ignoring return value" }
+ v.cend(); // { dg-warning "ignoring return value" }
+ v.crbegin(); // { dg-warning "ignoring return value" }
+ v.crend(); // { dg-warning "ignoring return value" }
+
+ auto i = v.begin(), j = v.end();
+ i == j; // { dg-warning "ignoring return value" }
+ i != j; // { dg-warning "ignoring return value" "PR c++/114104" { target
c++17_down } }
+ i < j; // { dg-warning "ignoring return value" }
+ i > j; // { dg-warning "ignoring return value" }
+ i <= j; // { dg-warning "ignoring return value" }
+ i >= j; // { dg-warning "ignoring return value" }
+
+ auto ci = cv.begin(), cj = cv.end();
+ ci == cj; // { dg-warning "ignoring return value" }
+ ci != cj; // { dg-warning "ignoring return value" "PR c++/114104" { target
c++17_down } }
+ ci < cj; // { dg-warning "ignoring return value" }
+ ci > cj; // { dg-warning "ignoring return value" }
+ ci <= cj; // { dg-warning "ignoring return value" }
+ ci >= cj; // { dg-warning "ignoring return value" }
+
+ ci == j; // { dg-warning "ignoring return value" }
+ ci != j; // { dg-warning "ignoring return value" "PR c++/114104" { target
c++17_down } }
+ ci < j; // { dg-warning "ignoring return value" }
+ ci > j; // { dg-warning "ignoring return value" }
+ ci <= j; // { dg-warning "ignoring return value" }
+ ci >= j; // { dg-warning "ignoring return value" }
+}
+
+void
+test_observers(std::vector<bool> v)
+{
+ v.size(); // { dg-warning "ignoring return value" }
+ v.capacity(); // { dg-warning "ignoring return value" }
+ v.empty(); // { dg-warning "ignoring return value" }
+}
+
+void
+test_element_access(std::vector<bool> v)
+{
+ v.front(); // { dg-warning "ignoring return value" }
+ v.back(); // { dg-warning "ignoring return value" }
+ v[1]; // { dg-warning "ignoring return value" }
+ v.at(1); // { dg-warning "ignoring return value" }
+ const auto& cv = v;
+ cv[1]; // { dg-warning "ignoring return value" }
+ cv.at(1); // { dg-warning "ignoring return value" }
+}
+
+void
+test_rel_ops(std::vector<bool> v)
+{
+ v == v; // { dg-warning "ignoring return value" }
+ v != v; // { dg-warning "ignoring return value" "PR c++/114104" { target
c++17_down } }
+ v < v; // { dg-warning "ignoring return value" }
+ v > v; // { dg-warning "ignoring return value" }
+ v <= v; // { dg-warning "ignoring return value" }
+ v >= v; // { dg-warning "ignoring return value" }
+}
+
+void
+test_iterators(std::vector<bool> v)
+{
+ v.begin(); // { dg-warning "ignoring return value" }
+ v.end(); // { dg-warning "ignoring return value" }
+ v.rbegin(); // { dg-warning "ignoring return value" }
+ v.rend(); // { dg-warning "ignoring return value" }
+ const auto& cv = v;
+ cv.begin(); // { dg-warning "ignoring return value" }
+ cv.end(); // { dg-warning "ignoring return value" }
+ cv.rbegin(); // { dg-warning "ignoring return value" }
+ cv.rend(); // { dg-warning "ignoring return value" }
+
+ v.cbegin(); // { dg-warning "ignoring return value" }
+ v.cend(); // { dg-warning "ignoring return value" }
+ v.crbegin(); // { dg-warning "ignoring return value" }
+ v.crend(); // { dg-warning "ignoring return value" }
+
+ auto i = v.begin(), j = v.end();
+ i == j; // { dg-warning "ignoring return value" }
+ i != j; // { dg-warning "ignoring return value" "PR c++/114104" { target
c++17_down } }
+ i < j; // { dg-warning "ignoring return value" }
+ i > j; // { dg-warning "ignoring return value" }
+ i <= j; // { dg-warning "ignoring return value" }
+ i >= j; // { dg-warning "ignoring return value" }
+
+ auto ci = cv.begin(), cj = cv.end();
+ ci == cj; // { dg-warning "ignoring return value" }
+ ci != cj; // { dg-warning "ignoring return value" "PR c++/114104" { target
c++17_down } }
+ ci < cj; // { dg-warning "ignoring return value" }
+ ci > cj; // { dg-warning "ignoring return value" }
+ ci <= cj; // { dg-warning "ignoring return value" }
+ ci >= cj; // { dg-warning "ignoring return value" }
+
+ ci == j; // { dg-warning "ignoring return value" }
+ ci != j; // { dg-warning "ignoring return value" "PR c++/114104" { target
c++17_down } }
+ ci < j; // { dg-warning "ignoring return value" }
+ ci > j; // { dg-warning "ignoring return value" }
+ ci <= j; // { dg-warning "ignoring return value" }
+ ci >= j; // { dg-warning "ignoring return value" }
+}
--
2.43.0
