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From: "bugs at sehe dot nl" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/51829] New: decltype() deduces non-const but only in a template Date: Wed, 11 Jan 2012 21:30:00 -0000 [thread overview] Message-ID: <bug-51829-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51829 Bug #: 51829 Summary: decltype() deduces non-const but only in a template Classification: Unclassified Product: gcc Version: 4.6.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned@gcc.gnu.org ReportedBy: bugs@sehe.nl The problem rejects a valid `auto expr = ...;` initialization. I have reduced things to the following (full preprocessed version attached) The template arguments aren't relevant (unused). #include <boost/spirit/include/qi_eps.hpp> template <typename> // without template, works! void bug() { const auto& e1 = boost::spirit::qi::eps(false); const auto& e2 = e1 | '1'; decltype(boost::spirit::qi::eps(false) | '1') *notok; notok = &e2; // FAILS if in template function } int main() { bug<void>(); } By using a pointer declaration for `notok` I was able to use demangling to print the difference between the deduced types: boost::proto::exprns_::expr<boost::proto::tagns_::tag::bitwise_or, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::terminal_ex<boost::spirit::tag::eps, boost::fusion::vector1<bool> > >, 0l> const&, boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<char const&>, 0l> >, 2l> boost::proto::exprns_::expr<boost::proto::tagns_::tag::bitwise_or, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::terminal_ex<boost::spirit::tag::eps, boost::fusion::vector1<bool> > >, 0l> CONST&, boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<char const&>, 0l> >, 2l> const* The 'CONST' I capitalized in the middle, is missing when the decltype() is in a function template, which prevents the assignment. I don't know how to further reduce the testcase at this point in time. MSVC 2010 compiles the code without problem.
next reply other threads:[~2012-01-11 21:30 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-01-11 21:30 bugs at sehe dot nl [this message] 2012-01-11 21:32 ` [Bug c++/51829] " bugs at sehe dot nl 2012-01-12 0:30 ` bugs at sehe dot nl 2012-01-13 12:05 ` paolo.carlini at oracle dot com 2012-05-12 23:04 ` paolo.carlini at oracle dot com 2012-05-13 3:38 ` bugs at sehe dot nl 2012-05-13 9:37 ` glisse at gcc dot gnu.org 2012-10-14 15:49 ` paolo.carlini at oracle dot com 2012-10-15 21:14 ` bugs at sehe dot nl
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