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| author | Jonathan Wakely <jwakely@redhat.com> | 2024-11-14 17:31:43 +0000 |
|---|---|---|
| committer | Jonathan Wakely <redi@gcc.gnu.org> | 2024-11-14 17:34:29 +0000 |
| commit | 4a3a0be34f723df192361e43bb48b9292dfe3a54 (patch) | |
| tree | 8f5ca39b3697ac95ef32c8751c88df37dec830eb /libstdc++-v3/testsuite/std/ranges | |
| parent | 5673fc0c7bab700395716207a52b3d4736e90ee3 (diff) | |
| download | gcc-4a3a0be34f723df192361e43bb48b9292dfe3a54.zip gcc-4a3a0be34f723df192361e43bb48b9292dfe3a54.tar.gz gcc-4a3a0be34f723df192361e43bb48b9292dfe3a54.tar.bz2 | |
libstdc++: Fix get<0> constraint for lvalue ranges::subrange (LWG 3589)
Apprived at October 2021 plenary.
libstdc++-v3/ChangeLog:
* include/bits/ranges_util.h (subrange::begin): Fix constraint,
as per LWG 3589.
* testsuite/std/ranges/subrange/lwg3589.cc: New test.
Diffstat (limited to 'libstdc++-v3/testsuite/std/ranges')
| -rw-r--r-- | libstdc++-v3/testsuite/std/ranges/subrange/lwg3589.cc | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/libstdc++-v3/testsuite/std/ranges/subrange/lwg3589.cc b/libstdc++-v3/testsuite/std/ranges/subrange/lwg3589.cc new file mode 100644 index 0000000..1ccc52d --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/subrange/lwg3589.cc @@ -0,0 +1,30 @@ +// { dg-do compile { target c++20 } } + +// LWG 3589. The const lvalue reference overload of get for subrange does not +// constrain I to be copyable when N == 0 + +#include <ranges> +#include <testsuite_iterators.h> + +void +test_lwg3589() +{ + int a[2]{}; + __gnu_test::test_range<int, __gnu_test::input_iterator_wrapper_nocopy> r(a); + + // Use a generic lambda so we have a dependent context. + auto test = [](auto& x) + { + // This was wrong before the LWG 3589 change: + if constexpr (requires { std::ranges::get<0>(x); }) + (void) std::ranges::get<0>(x); + + // These always worked unconditionally: + (void) std::ranges::get<1>(x); + (void) std::ranges::get<0>(std::move(x)); + (void) std::ranges::get<1>(std::move(x)); + }; + + std::ranges::subrange sr(r.begin(), r.end()); + test(sr); +} |