public inbox for libstdc++-cvs@sourceware.org help / color / mirror / Atom feed
From: Patrick Palka <ppalka@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r12-2357] libstdc++: invalid default init in _CachedPosition [PR101231] Date: Fri, 16 Jul 2021 13:47:02 +0000 (GMT) [thread overview] Message-ID: <20210716134702.6FD5E3889C0E@sourceware.org> (raw) https://gcc.gnu.org/g:1af937eb6246ad7f63ebff03590e9eede33aca81 commit r12-2357-g1af937eb6246ad7f63ebff03590e9eede33aca81 Author: Patrick Palka <ppalka@redhat.com> Date: Fri Jul 16 09:44:42 2021 -0400 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. Diff: --- libstdc++-v3/include/std/ranges | 2 +- libstdc++-v3/testsuite/std/ranges/istream_view.cc | 12 ++++++++++++ 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index df74ac9dc19..d791e15d096 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 369790e89e5..2f15f787250 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(); }
reply other threads:[~2021-07-16 13:47 UTC|newest] Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20210716134702.6FD5E3889C0E@sourceware.org \ --to=ppalka@gcc.gnu.org \ --cc=gcc-cvs@gcc.gnu.org \ --cc=libstdc++-cvs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).