libstdc++: Add workaround to std::ranges::subrange [PR111948]
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Commit Message
I think I'll push this to work around the compiler bug. We can revert it
later if the front end gets fixed.
Tested x86_64-linux. Needed on trunk and gcc-13.
-- >8 --
libstdc++-v3/ChangeLog:
PR libstdc++/111948
* include/bits/ranges_util.h (subrange): Add constructor to
_Size to aoid setting member in constructor.
* testsuite/std/ranges/subrange/111948.cc: New test.
---
libstdc++-v3/include/bits/ranges_util.h | 21 ++++++++++++-------
.../testsuite/std/ranges/subrange/111948.cc | 8 +++++++
2 files changed, 21 insertions(+), 8 deletions(-)
create mode 100644 libstdc++-v3/testsuite/std/ranges/subrange/111948.cc
Comments
On Thu, 30 Nov 2023 at 15:52, Jonathan Wakely <jwakely@redhat.com> wrote:
>
> I think I'll push this to work around the compiler bug. We can revert it
> later if the front end gets fixed.
>
> Tested x86_64-linux. Needed on trunk and gcc-13.
Pushed to trunk now.
>
> -- >8 --
>
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/111948
> * include/bits/ranges_util.h (subrange): Add constructor to
> _Size to aoid setting member in constructor.
> * testsuite/std/ranges/subrange/111948.cc: New test.
> ---
> libstdc++-v3/include/bits/ranges_util.h | 21 ++++++++++++-------
> .../testsuite/std/ranges/subrange/111948.cc | 8 +++++++
> 2 files changed, 21 insertions(+), 8 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/std/ranges/subrange/111948.cc
>
> diff --git a/libstdc++-v3/include/bits/ranges_util.h b/libstdc++-v3/include/bits/ranges_util.h
> index ab6c69c57d0..185e46ec7a9 100644
> --- a/libstdc++-v3/include/bits/ranges_util.h
> +++ b/libstdc++-v3/include/bits/ranges_util.h
> @@ -267,13 +267,21 @@ namespace ranges
> using __size_type
> = __detail::__make_unsigned_like_t<iter_difference_t<_It>>;
>
> - template<typename, bool = _S_store_size>
> + template<typename _Tp, bool = _S_store_size>
> struct _Size
> - { };
> + {
> + [[__gnu__::__always_inline__]]
> + constexpr _Size(_Tp = {}) { }
> + };
>
> template<typename _Tp>
> struct _Size<_Tp, true>
> - { _Tp _M_size; };
> + {
> + [[__gnu__::__always_inline__]]
> + constexpr _Size(_Tp __s = {}) : _M_size(__s) { }
> +
> + _Tp _M_size;
> + };
>
> [[no_unique_address]] _Size<__size_type> _M_size = {};
>
> @@ -294,11 +302,8 @@ namespace ranges
> noexcept(is_nothrow_constructible_v<_It, decltype(__i)>
> && is_nothrow_constructible_v<_Sent, _Sent&>)
> requires (_Kind == subrange_kind::sized)
> - : _M_begin(std::move(__i)), _M_end(__s)
> - {
> - if constexpr (_S_store_size)
> - _M_size._M_size = __n;
> - }
> + : _M_begin(std::move(__i)), _M_end(__s), _M_size(__n)
> + { }
>
> template<__detail::__different_from<subrange> _Rng>
> requires borrowed_range<_Rng>
> diff --git a/libstdc++-v3/testsuite/std/ranges/subrange/111948.cc b/libstdc++-v3/testsuite/std/ranges/subrange/111948.cc
> new file mode 100644
> index 00000000000..dcc64b56def
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/ranges/subrange/111948.cc
> @@ -0,0 +1,8 @@
> +// { dg-do compile { target c++20 } }
> +
> +#include <ranges>
> +
> +// Bug libstdc++/111948 - subrange modifies a const size object
> +
> +constexpr auto r = std::ranges::subrange(std::views::iota(0), 5);
> +static_assert(std::ranges::distance(r));
> --
> 2.43.0
>
@@ -267,13 +267,21 @@ namespace ranges
using __size_type
= __detail::__make_unsigned_like_t<iter_difference_t<_It>>;
- template<typename, bool = _S_store_size>
+ template<typename _Tp, bool = _S_store_size>
struct _Size
- { };
+ {
+ [[__gnu__::__always_inline__]]
+ constexpr _Size(_Tp = {}) { }
+ };
template<typename _Tp>
struct _Size<_Tp, true>
- { _Tp _M_size; };
+ {
+ [[__gnu__::__always_inline__]]
+ constexpr _Size(_Tp __s = {}) : _M_size(__s) { }
+
+ _Tp _M_size;
+ };
[[no_unique_address]] _Size<__size_type> _M_size = {};
@@ -294,11 +302,8 @@ namespace ranges
noexcept(is_nothrow_constructible_v<_It, decltype(__i)>
&& is_nothrow_constructible_v<_Sent, _Sent&>)
requires (_Kind == subrange_kind::sized)
- : _M_begin(std::move(__i)), _M_end(__s)
- {
- if constexpr (_S_store_size)
- _M_size._M_size = __n;
- }
+ : _M_begin(std::move(__i)), _M_end(__s), _M_size(__n)
+ { }
template<__detail::__different_from<subrange> _Rng>
requires borrowed_range<_Rng>
new file mode 100644
@@ -0,0 +1,8 @@
+// { dg-do compile { target c++20 } }
+
+#include <ranges>
+
+// Bug libstdc++/111948 - subrange modifies a const size object
+
+constexpr auto r = std::ranges::subrange(std::views::iota(0), 5);
+static_assert(std::ranges::distance(r));