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author | Patrick Palka <ppalka@redhat.com> | 2022-04-15 14:41:14 -0400 |
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committer | Patrick Palka <ppalka@redhat.com> | 2022-04-15 14:41:14 -0400 |
commit | 7e76cef873342a66408c126abceaf7dbddd3f477 (patch) | |
tree | 8a816011c97dd3edf618d648833df78980329f55 | |
parent | eb3f2e9348e8057f4219859a96739ff1ba350611 (diff) | |
download | gcc-7e76cef873342a66408c126abceaf7dbddd3f477.zip gcc-7e76cef873342a66408c126abceaf7dbddd3f477.tar.gz gcc-7e76cef873342a66408c126abceaf7dbddd3f477.tar.bz2 |
libstdc++: Avoid double-deref of __first in ranges::minmax [PR104858]
PR libstdc++/104858
libstdc++-v3/ChangeLog:
* include/bits/ranges_algo.h (__minmax_fn): Avoid dereferencing
__first twice at the start.
* testsuite/25_algorithms/minmax/constrained.cc (test06): New test.
-rw-r--r-- | libstdc++-v3/include/bits/ranges_algo.h | 2 | ||||
-rw-r--r-- | libstdc++-v3/testsuite/25_algorithms/minmax/constrained.cc | 30 |
2 files changed, 31 insertions, 1 deletions
diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h index 62dc605..3d30fb1 100644 --- a/libstdc++-v3/include/bits/ranges_algo.h +++ b/libstdc++-v3/include/bits/ranges_algo.h @@ -3084,7 +3084,7 @@ namespace ranges auto __last = ranges::end(__r); __glibcxx_assert(__first != __last); auto __comp_proj = __detail::__make_comp_proj(__comp, __proj); - minmax_result<range_value_t<_Range>> __result = {*__first, *__first}; + minmax_result<range_value_t<_Range>> __result = {*__first, __result.min}; if (++__first == __last) return __result; else diff --git a/libstdc++-v3/testsuite/25_algorithms/minmax/constrained.cc b/libstdc++-v3/testsuite/25_algorithms/minmax/constrained.cc index 90882af..5986404 100644 --- a/libstdc++-v3/testsuite/25_algorithms/minmax/constrained.cc +++ b/libstdc++-v3/testsuite/25_algorithms/minmax/constrained.cc @@ -20,6 +20,7 @@ #include <algorithm> #include <string> +#include <utility> #include <vector> #include <testsuite_hooks.h> #include <testsuite_iterators.h> @@ -129,6 +130,34 @@ test05() VERIFY( result.min == "a"s && result.max == "c"s ); } +struct A { + A() = delete; + A(int i) : i(i) { } + A(const A&) = default; + A(A&& other) : A(std::as_const(other)) { ++move_count; } + A& operator=(const A&) = default; + A& operator=(A&& other) { + ++move_count; + return *this = std::as_const(other); + }; + friend auto operator<=>(const A&, const A&) = default; + static inline int move_count = 0; + int i; +}; + +void +test06() +{ + // PR libstdc++/104858 + // Verify ranges::minmax doesn't dereference the iterator for the first + // element in the range twice. + A a(42); + ranges::subrange r = {std::move_iterator(&a), std::move_sentinel(&a + 1)}; + auto result = ranges::minmax(r); + VERIFY( A::move_count == 1 ); + VERIFY( result.min.i == 42 && result.max.i == 42 ); +} + int main() { @@ -137,4 +166,5 @@ main() test03(); test04(); test05(); + test06(); } |