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| author | Patrick Palka <ppalka@redhat.com> | 2021-07-16 09:44:42 -0400 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2021-07-16 09:44:42 -0400 |
| commit | 1af937eb6246ad7f63ebff03590e9eede33aca81 (patch) | |
| tree | 9c21bb371353baec99f9ac82667e07af93532494 | |
| parent | 73464a472aa4e86359f1a5dc529394fe5152fec0 (diff) | |
| download | gcc-1af937eb6246ad7f63ebff03590e9eede33aca81.zip gcc-1af937eb6246ad7f63ebff03590e9eede33aca81.tar.gz gcc-1af937eb6246ad7f63ebff03590e9eede33aca81.tar.bz2 | |
libstdc++: invalid default init in _CachedPosition [PR101231]
The primary template for _CachedPosition is a dummy implementation for
non-forward ranges, the iterators for which generally can't be cached.
Because this implementation doesn't actually cache anything, _M_has_value
is defined to be false and so calls to _M_get (which are always guarded
by _M_has_value) are unreachable.
Still, to suppress a "control reaches end of non-void function" warning
I made _M_get return {}, but after P2325 input iterators are no longer
necessarily default constructible so this workaround now breaks valid
programs.
This patch fixes this by instead using __builtin_unreachable to squelch
the warning.
PR libstdc++/101231
libstdc++-v3/ChangeLog:
* include/std/ranges (_CachedPosition::_M_get): For non-forward
ranges, just call __builtin_unreachable.
* testsuite/std/ranges/istream_view.cc (test05): New test.
| -rw-r--r-- | libstdc++-v3/include/std/ranges | 2 | ||||
| -rw-r--r-- | libstdc++-v3/testsuite/std/ranges/istream_view.cc | 12 |
2 files changed, 13 insertions, 1 deletions
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index df74ac9..d791e15 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -1232,7 +1232,7 @@ namespace views::__adaptor _M_get(const _Range&) const { __glibcxx_assert(false); - return {}; + __builtin_unreachable(); } constexpr void diff --git a/libstdc++-v3/testsuite/std/ranges/istream_view.cc b/libstdc++-v3/testsuite/std/ranges/istream_view.cc index 369790e..2f15f78 100644 --- a/libstdc++-v3/testsuite/std/ranges/istream_view.cc +++ b/libstdc++-v3/testsuite/std/ranges/istream_view.cc @@ -83,6 +83,17 @@ test04() static_assert(!std::forward_iterator<It>); } +void +test05() +{ + // PR libstdc++/101231 + auto words = std::istringstream{"42"}; + auto is = ranges::istream_view<int>(words); + auto r = is | views::filter([](auto) { return true; }); + for (auto x : r) + ; +} + int main() { @@ -90,4 +101,5 @@ main() test02(); test03(); test04(); + test05(); } |