I have just tested the same code clang 3.7. Here, everything compiles without warnings and works as expected.
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Von: Boost [boost-bounces@lists.boost.org]" im Auftrag von "Auer, Jens [jens.auer@cgi.com]
Gesendet: Donnerstag, 14. Januar 2016 21:28
An: boost@lists.boost.org
Betreff: [boost] Any-Range containing transformed range fails when compiled with optimizations
Hi,
I have a program which produces different results based on the compiler options. The program uses a boost::any_range containing a transformed range where the transformation function just returns a new object of a simple struct:
#include <vector>
#include
#include
#include
#include <iostream>
template void ASSERT_EQ(T1 x,T2 y) {assert(x == y);};
struct SourceEvent
{
std::uint32_t event;
void* ptr;
};
int main()
{
using boost::adaptors::transformed;
using R = boost::any_range;
std::vectorstd::int32_t v(100);
R r = v | transformed( [](auto const&) {return SourceEvent{0u, nullptr};} );
auto t = v | transformed( [](auto const&) {return SourceEvent{0u, nullptr};} );
ASSERT_EQ( 100u, boost::size(r) );
ASSERT_EQ( 100u, boost::size(t) );
for (auto const& i: t)
{
ASSERT_EQ(0u, i.event );
ASSERT_EQ(nullptr, i.ptr);
}
for (auto const& i: r)
{
ASSERT_EQ(0u, i.event );
ASSERT_EQ(nullptr, i.ptr);
}
std::cout << "OK" << std::endl;
return 0;
}
When compiled without optimization, it just prints ok. The same source compiled with optimizations asserts, and prints some interesting warnings:
In file included from /usr/local/boost-1.60.0/include/boost/range/detail/any_iterator.hpp:22:0,
from /usr/local/boost-1.60.0/include/boost/range/any_range.hpp:17,
from prog.cc:3:
/usr/local/boost-1.60.0/include/boost/range/detail/any_iterator_wrapper.hpp: In member function 'boost::range_detail::any_forward_iterator_wrapper::reference boost::range_detail::any_forward_iterator_wrapper::dereference() const [with WrappedIterator = boost::iterators::transform_iterator, SourceEvent>, __gnu_cxx::__normal_iterator, boost::iterators::use_default, boost::iterators::use_default>; Reference = SourceEvent; Buffer = boost::any_iterator_buffer<64ul>; boost::range_detail::any_forward_iterator_wrapper::reference = SourceEvent&]':
/usr/local/boost-1.60.0/include/boost/range/detail/any_iterator_wrapper.hpp:302:57: warning: function may return address of local variable [-Wreturn-local-addr]
return dereference_cast<reference>(*m_it);
^
/usr/local/boost-1.60.0/include/boost/range/detail/any_iterator_wrapper.hpp:302:52: note: declared here
return dereference_cast<reference>(*m_it);
^
prog.exe: prog.cc:7: void ASSERT_EQ(T1, T2) [with T1 = unsigned int; T2 = unsigned int]: Assertion `x == y' failed.
Aborted
The example is compiled with gcc 5.2 and boost 1.60 (http://melpon.org/wandbox/permlink/QF1qyw5bWHKwyKJ8). Is there an error in my code? I would guess that transforming a range into a range of new objects of another type is quite common, so it should work. I am also curious why the warning is only emitted when compiling with optimizations.
Best wishes,
Jens
--
Jens Auer | CGI | Software-Engineer
CGI (Germany) GmbH & Co. KG
Rheinstraße 95 | 64295 Darmstadt | Germany
T: +49 6151 36860 154
jens.auer@cgi.commailto:jens.auer@cgi.com
Unsere Pflichtangaben gemäß § 35a GmbHG / §§ 161, 125a HGB finden Sie unter de.cgi.com/pflichtangabenhttp://de.cgi.com/pflichtangaben.
CONFIDENTIALITY NOTICE: Proprietary/Confidential information belonging to CGI Group Inc. and its affiliates may be contained in this message. If you are not a recipient indicated or intended in this message (or responsible for delivery of this message to such person), or you think for any reason that this message may have been addressed to you in error, you may not use or copy or deliver this message to anyone else. In such case, you should destroy this message and are asked to notify the sender by reply e-mail.
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