From 08448dc146b6dd32383d64ab491a594d41f62aaa Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 24 Oct 2023 20:15:12 +0100
Subject: [PATCH] libstdc++: Add workaround to std::ranges::subrange [PR111948]
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 ab6c69c57d0b..185e46ec7a94 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 000000000000..dcc64b56def7
--- /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));
--
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