procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

libstdc++: Make std::string_view(Range&&) constructor explicit

Browse source 
The P2499R0 paper was recently approved for C++23.

libstdc++-v3/ChangeLog:

	* include/std/string_view (basic_string_view(Range&&)): Add
	explicit as per P2499R0.
	* testsuite/21_strings/basic_string_view/cons/char/range_c++20.cc:
	Adjust implicit conversions. Check implicit conversions fail.
	* testsuite/21_strings/basic_string_view/cons/wchar_t/range_c++20.cc:
	Likewise.
This commit is contained in:
Jonathan Wakely 2022-08-04 13:08:00 +01:00
parent db33daa467
commit 2678386df2
3 changed files with 50 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
libstdc++-v3/include/std/string_view
View file

@ -162,7 +162,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
})
&& (!requires { typename _DRange::traits_type; }
|| is_same_v<typename _DRange::traits_type, _Traits>)
constexpr
constexpr explicit
basic_string_view(_Range&& __r)
noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
: _M_len(ranges::size(__r)), _M_str(ranges::data(__r))

28
libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/range_c++20.cc
View file

@ -36,7 +36,7 @@ test01()
};
R r;
std::string_view s = r;
std::string_view s{r};
VERIFY( s == r.str );
VERIFY( s.data() == std::ranges::data(r) );
VERIFY( s.size() == std::ranges::size(r) );
@ -50,10 +50,15 @@ test01()
static_assert( std::ranges::contiguous_range<R2> );
static_assert( std::ranges::sized_range<R2> );
R2 r2;
std::string_view s2 = r2; // uses conversion to string_view
std::string_view s2(r2); // uses conversion to string_view
VERIFY( s2 == "Out of range" );
VERIFY( std::string_view(const_cast<const R2&>(r2)) == s2 );
// And again using copy-initialization instead of direct-initialization.
std::string_view s2_implicit = r2; // uses conversion to string_view
VERIFY( s2_implicit == "Out of range" );
VERIFY( std::string_view(const_cast<const R2&>(r2)) == s2_implicit );
struct R3 : R
{
using R::begin;
@ -91,7 +96,7 @@ test01()
static_assert( std::ranges::contiguous_range<R5> );
static_assert( std::ranges::sized_range<R5> );
R5 r5;
std::string_view s5 = r5; // Uses range constructor
std::string_view s5(r5); // Uses range constructor
VERIFY( s5 == r5.str );
s5 = std::string_view(std::move(r5)); // In C++20 this used conversion op.
VERIFY( s5 == r5.str ); // In C++23 it uses range constructor.
@ -156,15 +161,30 @@ test04()
};
R r;
std::basic_string_view s = r; // Use deduction guide.
std::basic_string_view s(r); // Use deduction guide.
static_assert( std::is_same_v<decltype(s), std::string_view> );
}
void
test05()
{
struct R
{
const char* begin() const { return nullptr; }
const char* end() const { return nullptr; }
};
// P2499R0 string_view range constructor should be explicit
// P2516R0 string_view is implicitly convertible from what?
static_assert( ! std::is_convertible_v<R, std::string_view> );
}
int main()
{
test01();
test02();
test03();
test04();
test05();
}

30
libstdc++-v3/testsuite/21_strings/basic_string_view/cons/wchar_t/range_c++20.cc
View file

@ -36,7 +36,7 @@ test01()
};
R r;
std::wstring_view s = r;
std::wstring_view s{r};
VERIFY( s == r.str );
VERIFY( s.data() == std::ranges::data(r) );
VERIFY( s.size() == std::ranges::size(r) );
@ -50,10 +50,15 @@ test01()
static_assert( std::ranges::contiguous_range<R2> );
static_assert( std::ranges::sized_range<R2> );
R2 r2;
std::wstring_view s2 = r2; // uses conversion to wstring_view
std::wstring_view s2(r2); // uses conversion to wstring_view
VERIFY( s2 == L"Out of range" );
VERIFY( std::wstring_view(const_cast<const R2&>(r2)) == s2 );
// And again using copy-initialization instead of direct-initialization.
std::wstring_view s2_implicit = r2; // uses conversion to wstring_view
VERIFY( s2_implicit == L"Out of range" );
VERIFY( std::wstring_view(const_cast<const R2&>(r2)) == s2_implicit );
struct R3 : R
{
using R::begin;
@ -91,10 +96,10 @@ test01()
static_assert( std::ranges::contiguous_range<R5> );
static_assert( std::ranges::sized_range<R5> );
R5 r5;
std::wstring_view s5 = r5; // Uses range constructor
std::wstring_view s5(r5); // Uses range constructor
VERIFY( s5 == r5.str );
s5 = std::wstring_view(std::move(r5)); // In C++20 this used conversion op.
VERIFY( s5 == r5.str ); // In C++23 it uses range constructor.
VERIFY( s5 == r5.str ); // In C++23 it uses range constructor.
wchar_t arr[] = L"arrangement\0with\0nulls";
std::wstring_view sa = arr; // Does not use range constructor
@ -156,15 +161,30 @@ test04()
};
R r;
std::basic_string_view s = r; // Use deduction guide.
std::basic_string_view s(r); // Use deduction guide.
static_assert( std::is_same_v<decltype(s), std::wstring_view> );
}
void
test05()
{
struct R
{
const wchar_t* begin() const { return nullptr; }
const wchar_t* end() const { return nullptr; }
};
// P2499R0 string_view range constructor should be explicit
// P2516R0 string_view is implicitly convertible from what?
static_assert( ! std::is_convertible_v<R, std::wstring_view> );
}
int main()
{
test01();
test02();
test03();
test04();
test05();
}