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[libc++] [ranges] Fix bugs in ranges::empty(). 

It was missing the cast to `bool` in `bool(__t.empty())`.
It was wrongly using `std::forward` in some places.

Differential Revision: https://reviews.llvm.org/D115312
This commit is contained in:
Arthur O'Dwyer 2021-12-22 18:06:48 -05:00
parent 6842f52a0b
commit a2a9a5c7d3
2 changed files with 15 additions and 14 deletions
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11
libcxx/include/__ranges/empty.h
View File

@ -13,7 +13,6 @@
#include <__iterator/concepts.h>
#include <__ranges/access.h>
#include <__ranges/size.h>
#include <__utility/forward.h>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@ -29,13 +28,13 @@ namespace ranges {
namespace __empty {
template <class _Tp>
concept __member_empty = requires(_Tp&& __t) {
bool(_VSTD::forward<_Tp>(__t).empty());
bool(__t.empty());
};
template<class _Tp>
concept __can_invoke_size =
!__member_empty<_Tp> &&
requires(_Tp&& __t) { ranges::size(_VSTD::forward<_Tp>(__t)); };
requires(_Tp&& __t) { ranges::size(__t); };
template <class _Tp>
concept __can_compare_begin_end =
@ -50,13 +49,13 @@ namespace __empty {
template <__member_empty _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_Tp&& __t) const
noexcept(noexcept(bool(__t.empty()))) {
return __t.empty();
return bool(__t.empty());
}
template <__can_invoke_size _Tp>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_Tp&& __t) const
noexcept(noexcept(ranges::size(_VSTD::forward<_Tp>(__t)))) {
return ranges::size(_VSTD::forward<_Tp>(__t)) == 0;
noexcept(noexcept(ranges::size(__t))) {
return ranges::size(__t) == 0;
}
template<__can_compare_begin_end _Tp>

18
libcxx/test/std/ranges/range.access/empty.pass.cpp
View File

@ -15,11 +15,11 @@
#include <ranges>
#include <cassert>
#include <utility>
#include "test_macros.h"
#include "test_iterators.h"
using RangeEmptyT = decltype(std::ranges::empty);
using RangeSizeT = decltype(std::ranges::size);
static_assert(!std::is_invocable_v<RangeEmptyT, int[]>);
static_assert(!std::is_invocable_v<RangeEmptyT, int(&)[]>);
@ -41,12 +41,16 @@ static_assert(!std::ranges::empty(std::move(array_of_incomplete)));
static_assert(!std::ranges::empty(std::as_const(array_of_incomplete)));
static_assert(!std::ranges::empty(static_cast<const Incomplete(&&)[42]>(array_of_incomplete)));
struct NonConstSizeAndEmpty {
int size();
struct InputRangeWithoutSize {
cpp17_input_iterator<int*> begin() const;
cpp17_input_iterator<int*> end() const;
};
static_assert(!std::is_invocable_v<RangeEmptyT, const InputRangeWithoutSize&>);
struct NonConstEmpty {
bool empty();
};
static_assert(!std::is_invocable_v<RangeSizeT, const NonConstSizeAndEmpty&>);
static_assert(!std::is_invocable_v<RangeEmptyT, const NonConstSizeAndEmpty&>);
static_assert(!std::is_invocable_v<RangeEmptyT, const NonConstEmpty&>);
struct HasMemberAndFunction {
constexpr bool empty() const { return true; }
@ -60,7 +64,7 @@ struct BadReturnType {
static_assert(!std::is_invocable_v<RangeEmptyT, BadReturnType&>);
struct BoolConvertible {
constexpr /*TODO: explicit*/ operator bool() noexcept(false) { return true; }
constexpr explicit operator bool() noexcept(false) { return true; }
};
struct BoolConvertibleReturnType {
constexpr BoolConvertible empty() noexcept { return {}; }
@ -159,9 +163,7 @@ constexpr bool testBeginEqualsEnd() {
assert(std::ranges::empty(e) == false); // e.empty()
assert(std::ranges::empty(std::as_const(e)) == true); // e.begin() == e.end()
#if 0 // TODO FIXME
assert(std::ranges::empty(EvilBeginEnd()));
#endif
return true;
}