Re: [committed 2/2] libstdc++: Add [[nodiscard]] to sequence containers
On 04/08/21 13:00 +0100, Jonathan Wakely wrote:
On 04/08/21 12:56 +0100, Jonathan Wakely wrote:
... and container adaptors.
This adds the [[nodiscard]] attribute to functions with no side-effects
for the sequence containers and their iterators, and the debug versions
of those containers, and the container adaptors,
I don't plan to add any more [[nodiscard]] attributes for now, but
these two commits should demonstrate how to do it for anybody who
wants to contribute similar patches.
OK, one more change in this vein, adding [[nodiscard]] to .
Tested powerpc64le-linux, committed to trunk.
commit 8dec72aeb54e98643c0fb3d53768cdb96cf1342a
Author: Jonathan Wakely
Date: Thu Aug 5 14:01:31 2021
libstdc++: Add [[nodiscard]] to
This adds the [[nodiscard]] attribute to all conversion operators,
comparison operators, call operators and non-member functions in
. Nothing in this header except constructors has side effects.
Signed-off-by: Jonathan Wakely
libstdc++-v3/ChangeLog:
* libsupc++/compare (partial_ordering, weak_ordering)
(strong_ordering, is_eq, is_neq, is_lt, is_lteq, is_gt, is_gteq)
(compare_three_way, strong_order, weak_order, partial_order)
(compare_strong_order_fallback, compare_weak_order_fallback)
(compare_partial_order_fallback, __detail::__synth3way): Add
nodiscard attribute.
* testsuite/18_support/comparisons/categories/zero_neg.cc: Add
-Wno-unused-result to options.
diff --git a/libstdc++-v3/libsupc++/compare b/libstdc++-v3/libsupc++/compare
index dd0ec5fa36d..faeff641437 100644
--- a/libstdc++-v3/libsupc++/compare
+++ b/libstdc++-v3/libsupc++/compare
@@ -86,49 +86,61 @@ namespace std
static const partial_ordering unordered;
// comparisons
+[[nodiscard]]
friend constexpr bool
operator==(partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == 0; }
+[[nodiscard]]
friend constexpr bool
operator==(partial_ordering, partial_ordering) noexcept = default;
+[[nodiscard]]
friend constexpr bool
operator< (partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == -1; }
+[[nodiscard]]
friend constexpr bool
operator> (partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == 1; }
+[[nodiscard]]
friend constexpr bool
operator<=(partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value <= 0; }
+[[nodiscard]]
friend constexpr bool
operator>=(partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __cmp_cat::type(__v._M_value & 1) == __v._M_value; }
+[[nodiscard]]
friend constexpr bool
operator< (__cmp_cat::__unspec, partial_ordering __v) noexcept
{ return __v._M_value == 1; }
+[[nodiscard]]
friend constexpr bool
operator> (__cmp_cat::__unspec, partial_ordering __v) noexcept
{ return __v._M_value == -1; }
+[[nodiscard]]
friend constexpr bool
operator<=(__cmp_cat::__unspec, partial_ordering __v) noexcept
{ return __cmp_cat::type(__v._M_value & 1) == __v._M_value; }
+[[nodiscard]]
friend constexpr bool
operator>=(__cmp_cat::__unspec, partial_ordering __v) noexcept
{ return 0 >= __v._M_value; }
+[[nodiscard]]
friend constexpr partial_ordering
operator<=>(partial_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v; }
+[[nodiscard]]
friend constexpr partial_ordering
operator<=>(__cmp_cat::__unspec, partial_ordering __v) noexcept
{
@@ -168,53 +180,66 @@ namespace std
static const weak_ordering equivalent;
static const weak_ordering greater;
+[[nodiscard]]
constexpr operator partial_ordering() const noexcept
{ return partial_ordering(__cmp_cat::_Ord(_M_value)); }
// comparisons
+[[nodiscard]]
friend constexpr bool
operator==(weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value == 0; }
+[[nodiscard]]
friend constexpr bool
operator==(weak_ordering, weak_ordering) noexcept = default;
+[[nodiscard]]
friend constexpr bool
operator< (weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value < 0; }
+[[nodiscard]]
friend constexpr bool
operator> (weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value > 0; }
+[[nodiscard]]
friend constexpr bool
operator<=(weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value <= 0; }
+[[nodiscard]]
friend constexpr bool
operator>=(weak_ordering __v, __cmp_cat::__unspec) noexcept
{ return __v._M_value >= 0; }
+[[nodiscard]]
friend constexpr bool
operator< (__cmp_cat::__unspec, weak_ordering __v) noexcept
{ return 0 < __v._M_value; }
+[[nodiscard]]
friend constexpr
Re: [committed 2/2] libstdc++: Add [[nodiscard]] to sequence containers
On Thu, 5 Aug 2021 at 13:14, Ville Voutilainen
wrote:
>
> On Thu, 5 Aug 2021 at 15:11, Christophe Lyon via Libstdc++
> wrote:
> >
> > Hi Jonathan,
> >
> > On Wed, Aug 4, 2021 at 2:04 PM Jonathan Wakely via Gcc-patches <
> > gcc-patches@gcc.gnu.org> wrote:
> >
> > > On 04/08/21 12:56 +0100, Jonathan Wakely wrote:
> > > >... and container adaptors.
> > > >
> > > >This adds the [[nodiscard]] attribute to functions with no side-effects
> > > >for the sequence containers and their iterators, and the debug versions
> > > >of those containers, and the container adaptors,
> > >
> > > I don't plan to add any more [[nodiscard]] attributes for now, but
> > > these two commits should demonstrate how to do it for anybody who
> > > wants to contribute similar patches.
> > >
> > > I didn't add tests that verify we do actually warn on each of those
> > > functions, because there are hundreds of them, and I know they're
> > > working because I had to alter existing tests to not warn.
> > >
> > >
> > I've noticed a regression on aarch64/arm:
> > FAIL: g++.old-deja/g++.other/inline7.C -std=gnu++17 (test for excess
> > errors)
> > Excess errors:
> > /gcc/testsuite/g++.old-deja/g++.other/inline7.C:11:11: warning: ignoring
> > return value of 'std::__cxx11::list<_Tp, _Alloc>::size_type
> > std::__cxx11::list<_Tp, _Alloc>::size() const [with _Tp = int*; _Alloc =
> > std::allocator; std::__cxx11::list<_Tp, _Alloc>::size_type = long
> > unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
> >
> > FAIL: g++.old-deja/g++.other/inline7.C -std=gnu++2a (test for excess
> > errors)
> > Excess errors:
> > /gcc/testsuite/g++.old-deja/g++.other/inline7.C:11:11: warning: ignoring
> > return value of 'std::__cxx11::list<_Tp, _Alloc>::size_type
> > std::__cxx11::list<_Tp, _Alloc>::size() const [with _Tp = int*; _Alloc =
> > std::allocator; std::__cxx11::list<_Tp, _Alloc>::size_type = long
> > unsigned int]', declared with attribute 'nodiscard' [-Wunused-result]
> >
> > Not sure why you didn't see it?
>
> That can easily happen when running just the library tests, rather
> than all of them. :P
Right, I didn't run all the compiler tests.
Fixed with this patch, tested x86_64-linux, pushed to trunk.
commit 03d47da7e1e91adddbde261ffefd2760df59a564
Author: Jonathan Wakely
Date: Thu Aug 5 14:00:35 2021
testsuite: Fix warning introduced by nodiscard in libstdc++
Signed-off-by: Jonathan Wakely
gcc/testsuite/ChangeLog:
* g++.old-deja/g++.other/inline7.C: Cast nodiscard call to void.
diff --git a/gcc/testsuite/g++.old-deja/g++.other/inline7.C
b/gcc/testsuite/g++.old-deja/g++.other/inline7.C
index a3723cfba1e..62639c5 100644
--- a/gcc/testsuite/g++.old-deja/g++.other/inline7.C
+++ b/gcc/testsuite/g++.old-deja/g++.other/inline7.C
@@ -8,7 +8,7 @@ std::list li;
void f ()
{
- li.size ();
+ (void) li.size ();
}
int main ()
Re: [committed 2/2] libstdc++: Add [[nodiscard]] to sequence containers
On Thu, 5 Aug 2021 at 15:11, Christophe Lyon via Libstdc++ wrote: > > Hi Jonathan, > > On Wed, Aug 4, 2021 at 2:04 PM Jonathan Wakely via Gcc-patches < > gcc-patches@gcc.gnu.org> wrote: > > > On 04/08/21 12:56 +0100, Jonathan Wakely wrote: > > >... and container adaptors. > > > > > >This adds the [[nodiscard]] attribute to functions with no side-effects > > >for the sequence containers and their iterators, and the debug versions > > >of those containers, and the container adaptors, > > > > I don't plan to add any more [[nodiscard]] attributes for now, but > > these two commits should demonstrate how to do it for anybody who > > wants to contribute similar patches. > > > > I didn't add tests that verify we do actually warn on each of those > > functions, because there are hundreds of them, and I know they're > > working because I had to alter existing tests to not warn. > > > > > I've noticed a regression on aarch64/arm: > FAIL: g++.old-deja/g++.other/inline7.C -std=gnu++17 (test for excess > errors) > Excess errors: > /gcc/testsuite/g++.old-deja/g++.other/inline7.C:11:11: warning: ignoring > return value of 'std::__cxx11::list<_Tp, _Alloc>::size_type > std::__cxx11::list<_Tp, _Alloc>::size() const [with _Tp = int*; _Alloc = > std::allocator; std::__cxx11::list<_Tp, _Alloc>::size_type = long > unsigned int]', declared with attribute 'nodiscard' [-Wunused-result] > > FAIL: g++.old-deja/g++.other/inline7.C -std=gnu++2a (test for excess > errors) > Excess errors: > /gcc/testsuite/g++.old-deja/g++.other/inline7.C:11:11: warning: ignoring > return value of 'std::__cxx11::list<_Tp, _Alloc>::size_type > std::__cxx11::list<_Tp, _Alloc>::size() const [with _Tp = int*; _Alloc = > std::allocator; std::__cxx11::list<_Tp, _Alloc>::size_type = long > unsigned int]', declared with attribute 'nodiscard' [-Wunused-result] > > Not sure why you didn't see it? That can easily happen when running just the library tests, rather than all of them. :P
Re: [committed 2/2] libstdc++: Add [[nodiscard]] to sequence containers
Hi Jonathan, On Wed, Aug 4, 2021 at 2:04 PM Jonathan Wakely via Gcc-patches < gcc-patches@gcc.gnu.org> wrote: > On 04/08/21 12:56 +0100, Jonathan Wakely wrote: > >... and container adaptors. > > > >This adds the [[nodiscard]] attribute to functions with no side-effects > >for the sequence containers and their iterators, and the debug versions > >of those containers, and the container adaptors, > > I don't plan to add any more [[nodiscard]] attributes for now, but > these two commits should demonstrate how to do it for anybody who > wants to contribute similar patches. > > I didn't add tests that verify we do actually warn on each of those > functions, because there are hundreds of them, and I know they're > working because I had to alter existing tests to not warn. > > I've noticed a regression on aarch64/arm: FAIL: g++.old-deja/g++.other/inline7.C -std=gnu++17 (test for excess errors) Excess errors: /gcc/testsuite/g++.old-deja/g++.other/inline7.C:11:11: warning: ignoring return value of 'std::__cxx11::list<_Tp, _Alloc>::size_type std::__cxx11::list<_Tp, _Alloc>::size() const [with _Tp = int*; _Alloc = std::allocator; std::__cxx11::list<_Tp, _Alloc>::size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result] FAIL: g++.old-deja/g++.other/inline7.C -std=gnu++2a (test for excess errors) Excess errors: /gcc/testsuite/g++.old-deja/g++.other/inline7.C:11:11: warning: ignoring return value of 'std::__cxx11::list<_Tp, _Alloc>::size_type std::__cxx11::list<_Tp, _Alloc>::size() const [with _Tp = int*; _Alloc = std::allocator; std::__cxx11::list<_Tp, _Alloc>::size_type = long unsigned int]', declared with attribute 'nodiscard' [-Wunused-result] Not sure why you didn't see it? Christophe
Re: [committed 2/2] libstdc++: Add [[nodiscard]] to sequence containers
On 04/08/21 12:56 +0100, Jonathan Wakely wrote: ... and container adaptors. This adds the [[nodiscard]] attribute to functions with no side-effects for the sequence containers and their iterators, and the debug versions of those containers, and the container adaptors, I don't plan to add any more [[nodiscard]] attributes for now, but these two commits should demonstrate how to do it for anybody who wants to contribute similar patches. I didn't add tests that verify we do actually warn on each of those functions, because there are hundreds of them, and I know they're working because I had to alter existing tests to not warn.
[committed 2/2] libstdc++: Add [[nodiscard]] to sequence containers
... and container adaptors.
This adds the [[nodiscard]] attribute to functions with no side-effects
for the sequence containers and their iterators, and the debug versions
of those containers, and the container adaptors,
Tested powerpc64le-linux, committed to trunk.
commit 0d04fe49239d91787850036599164788f1c87785
Author: Jonathan Wakely
Date: Tue Aug 3 20:50:52 2021
libstdc++: Add [[nodiscard]] to sequence containers
... and container adaptors.
This adds the [[nodiscard]] attribute to functions with no side-effects
for the sequence containers and their iterators, and the debug versions
of those containers, and the container adaptors,
Signed-off-by: Jonathan Wakely
libstdc++-v3/ChangeLog:
* include/bits/forward_list.h: Add [[nodiscard]] to functions
with no side-effects.
* include/bits/stl_bvector.h: Likewise.
* include/bits/stl_deque.h: Likewise.
* include/bits/stl_list.h: Likewise.
* include/bits/stl_queue.h: Likewise.
* include/bits/stl_stack.h: Likewise.
* include/bits/stl_vector.h: Likewise.
* include/debug/deque: Likewise.
* include/debug/forward_list: Likewise.
* include/debug/list: Likewise.
* include/debug/safe_iterator.h: Likewise.
* include/debug/vector: Likewise.
* include/std/array: Likewise.
* testsuite/23_containers/array/creation/3_neg.cc: Use
-Wno-unused-result.
* testsuite/23_containers/array/debug/back1_neg.cc: Cast result
to void.
* testsuite/23_containers/array/debug/back2_neg.cc: Likewise.
* testsuite/23_containers/array/debug/front1_neg.cc: Likewise.
* testsuite/23_containers/array/debug/front2_neg.cc: Likewise.
* testsuite/23_containers/array/debug/square_brackets_operator1_neg.cc:
Likewise.
* testsuite/23_containers/array/debug/square_brackets_operator2_neg.cc:
Likewise.
* testsuite/23_containers/array/tuple_interface/get_neg.cc:
Adjust dg-error line numbers.
* testsuite/23_containers/deque/cons/clear_allocator.cc: Cast
result to void.
* testsuite/23_containers/deque/debug/invalidation/4.cc:
Likewise.
* testsuite/23_containers/deque/types/1.cc: Use
-Wno-unused-result.
* testsuite/23_containers/list/types/1.cc: Cast result to void.
* testsuite/23_containers/priority_queue/members/7161.cc:
Likewise.
* testsuite/23_containers/queue/members/7157.cc: Likewise.
* testsuite/23_containers/vector/59829.cc: Likewise.
* testsuite/23_containers/vector/ext_pointer/types/1.cc:
Likewise.
* testsuite/23_containers/vector/ext_pointer/types/2.cc:
Likewise.
* testsuite/23_containers/vector/types/1.cc: Use
-Wno-unused-result.
diff --git a/libstdc++-v3/include/bits/forward_list.h b/libstdc++-v3/include/bits/forward_list.h
index e61746848f6..ab6d9389194 100644
--- a/libstdc++-v3/include/bits/forward_list.h
+++ b/libstdc++-v3/include/bits/forward_list.h
@@ -150,10 +150,12 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_Fwd_list_iterator(_Fwd_list_node_base* __n) noexcept
: _M_node(__n) { }
+ [[__nodiscard__]]
reference
operator*() const noexcept
{ return *static_cast<_Node*>(this->_M_node)->_M_valptr(); }
+ [[__nodiscard__]]
pointer
operator->() const noexcept
{ return static_cast<_Node*>(this->_M_node)->_M_valptr(); }
@@ -176,6 +178,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
/**
* @brief Forward list iterator equality comparison.
*/
+ [[__nodiscard__]]
friend bool
operator==(const _Self& __x, const _Self& __y) noexcept
{ return __x._M_node == __y._M_node; }
@@ -184,6 +187,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
/**
* @brief Forward list iterator inequality comparison.
*/
+ [[__nodiscard__]]
friend bool
operator!=(const _Self& __x, const _Self& __y) noexcept
{ return __x._M_node != __y._M_node; }
@@ -229,10 +233,12 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_Fwd_list_const_iterator(const iterator& __iter) noexcept
: _M_node(__iter._M_node) { }
+ [[__nodiscard__]]
reference
operator*() const noexcept
{ return *static_cast<_Node*>(this->_M_node)->_M_valptr(); }
+ [[__nodiscard__]]
pointer
operator->() const noexcept
{ return static_cast<_Node*>(this->_M_node)->_M_valptr(); }
@@ -255,6 +261,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
/**
* @brief Forward list const_iterator equality comparison.
*/
+ [[__nodiscard__]]
friend bool
operator==(const _Self& __x, const
