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[libc++][ranges] Applied [[nodiscard]] to as_rvalue_view #173145

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[libc++][ranges] Applied [[nodiscard]] to as_rvalue_view #173145

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16 changes: 8 additions & 8 deletions libcxx/include/__ranges/as_rvalue_view.h
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Original file line number Diff line number Diff line change
Expand Up @@ -48,27 +48,27 @@ class as_rvalue_view : public view_interface<as_rvalue_view<_View>> {

_LIBCPP_HIDE_FROM_ABI constexpr explicit as_rvalue_view(_View __base) : __base_(std::move(__base)) {}

_LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
requires copy_constructible<_View>
{
return __base_;
}

_LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }

_LIBCPP_HIDE_FROM_ABI constexpr auto begin()
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto begin()
requires(!__simple_view<_View>)
{
return move_iterator(ranges::begin(__base_));
}

_LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
requires range<const _View>
{
return move_iterator(ranges::begin(__base_));
}

_LIBCPP_HIDE_FROM_ABI constexpr auto end()
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto end()
requires(!__simple_view<_View>)
{
if constexpr (common_range<_View>) {
Expand All @@ -78,7 +78,7 @@ class as_rvalue_view : public view_interface<as_rvalue_view<_View>> {
}
}

_LIBCPP_HIDE_FROM_ABI constexpr auto end() const
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
requires range<const _View>
{
if constexpr (common_range<const _View>) {
Expand All @@ -88,13 +88,13 @@ class as_rvalue_view : public view_interface<as_rvalue_view<_View>> {
}
}

_LIBCPP_HIDE_FROM_ABI constexpr auto size()
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto size()
requires sized_range<_View>
{
return ranges::size(__base_);
}

_LIBCPP_HIDE_FROM_ABI constexpr auto size() const
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
requires sized_range<const _View>
{
return ranges::size(__base_);
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63 changes: 63 additions & 0 deletions libcxx/test/libcxx/ranges/range.adaptors/range.as_rvalue_view/nodiscard.verify.cpp
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Original file line number Diff line number Diff line change
@@ -0,0 +1,63 @@
//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// REQUIRES: std-at-least-c++23

// Check that functions are marked [[nodiscard]]

#include <ranges>
#include <utility>

#include "test_range.h"

struct NonSimpleView : std::ranges::view_base {
int* begin() const;
int* end() const;

const int* begin();
const int* end();

constexpr std::size_t size() { return 0; };
};
static_assert(!simple_view<NonSimpleView>);

void test() {
NonSimpleView range;

auto v = std::views::as_rvalue(range);

// [range.as.rvalue.view]

// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
v.base();
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::move(v).base();

// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
v.begin();
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::as_const(v).begin();

// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
v.end();
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::as_const(v).end();

// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
v.size();
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::as_const(v).size();

// [range.as.rvalue.overview]

// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::views::as_rvalue(range);

// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
std::views::as_rvalue(v);
}
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