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From: "bangerth at dealii dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/33518] unused code changes the result of name lookup Date: Sun, 23 Sep 2007 18:09:00 -0000 [thread overview] Message-ID: <20070923180911.20975.qmail@sourceware.org> (raw) In-Reply-To: <bug-33518-6008@http.gcc.gnu.org/bugzilla/> ------- Comment #2 from bangerth at dealii dot org 2007-09-23 18:09 ------- This indeed looks like a bug. Take this: --------------------- #include <iterator> namespace M { struct A {}; using std::distance; } namespace N { template <class> struct S {}; class Q : S<M::A> {}; int distance(Q,Q); } int i = distance (N::Q(), N::Q()); ---------------- I would expect this to compile: all arguments to the call to distance() have associated namespace N, so we would expect that the compiler finds N::distance. However, apparently, gcc also performs the derived-to-base conversion to find S<M::A> and concludes that namespace M is also associated from where it tries to use std::distance and gives the error g/x> c++ -c y.cc /usr/include/c++/4.1.2/bits/stl_iterator_base_types.h: In instantiation of 'std::iterator_traits<N::Q>': y.cc:15: instantiated from here /usr/include/c++/4.1.2/bits/stl_iterator_base_types.h:129: error: no type named 'iterator_category' in 'class N::Q' /usr/include/c++/4.1.2/bits/stl_iterator_base_types.h:130: error: no type named 'value_type' in 'class N::Q' /usr/include/c++/4.1.2/bits/stl_iterator_base_types.h:131: error: no type named 'difference_type' in 'class N::Q' /usr/include/c++/4.1.2/bits/stl_iterator_base_types.h:132: error: no type named 'pointer' in 'class N::Q' /usr/include/c++/4.1.2/bits/stl_iterator_base_types.h:133: error: no type named 'reference' in 'class N::Q' It shouldn't be hard to produce a wrong-code bug from this. If someone wants to beat me to producing something without the include file, feel free... W. -- bangerth at dealii dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Ever Confirmed|0 |1 Last reconfirmed|0000-00-00 00:00:00 |2007-09-23 18:09:10 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33518
next prev parent reply other threads:[~2007-09-23 18:09 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2007-09-21 15:40 [Bug c++/33518] New: " marc dot glisse at normalesup dot org 2007-09-22 4:32 ` [Bug c++/33518] " bangerth at dealii dot org 2007-09-23 18:09 ` bangerth at dealii dot org [this message] 2007-09-23 18:23 ` [Bug c++/33518] invalid Koenig lookup bangerth at dealii dot org 2007-09-23 18:29 ` [Bug c++/33518] invalid Koenig lookup/incorrect SFINAE bangerth at dealii dot org 2007-09-23 19:58 ` rguenth at gcc dot gnu dot org 2007-09-23 20:57 ` bangerth at dealii dot org
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