Problem with gnu libc++ 4.7's chrono in Clang 3.2

Hi,

Compiling the following 1-line file:

#include <condition_variable>

Causes the error:

$ clang++ -std=c++11 ./foo.cpp
In file included from ./foo.cpp:1:
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.7/…/…/…/…/include/c++/4.7/condition_variable:37:
/usr/lib/gcc/x86_64-linux-gnu/4.7/…/…/…/…/include/c++/4.7/chrono:539:6: error: no matching constructor for
initialization of ‘duration’ (aka ‘std::chrono::duration<long, std::ratio<1, 1000000> >’)
: __d(__t.time_since_epoch())
^ ~~~~~~~~~~~~~~~~~~~~~~
/usr/lib/gcc/x86_64-linux-gnu/4.7/…/…/…/…/include/c++/4.7/condition_variable:110:42: note: in instantiation of
function template specialization ‘std::chrono::time_point<std::chrono::system_clock, std::chrono::duration<long,
std::ratio<1, 1000000> > >::time_point<std::chrono::duration<long, std::ratio<1, 1000000000> > >’ requested here
const __clock_t::time_point __s_atime = __s_entry + __delta;
^
/usr/lib/gcc/x86_64-linux-gnu/4.7/…/…/…/…/include/c++/4.7/chrono:233:12: note: candidate constructor not viable: no
known conversion from ‘duration<[…], ratio<[…], 1000000000>>’ to ‘duration<[…], ratio<[…], 1000000>>’
for 1st argument
constexpr duration(const duration&) = default;
^
/usr/lib/gcc/x86_64-linux-gnu/4.7/…/…/…/…/include/c++/4.7/chrono:239:23: note: candidate template ignored: couldn’t
infer template argument ‘’
constexpr explicit duration(const _Rep2& __rep)
^
/usr/lib/gcc/x86_64-linux-gnu/4.7/…/…/…/…/include/c++/4.7/chrono:246:14: note: candidate template ignored: couldn’t
infer template argument ‘’
constexpr duration(const duration<_Rep2, _Period2>& __d)
^
/usr/lib/gcc/x86_64-linux-gnu/4.7/…/…/…/…/include/c++/4.7/chrono:231:12: note: candidate constructor not viable:
requires 0 arguments, but 1 was provided
constexpr duration() : __r() { }
^
1 error generated.

Searching the web doesn’t turn up anything related.

This is on Ubuntu 12.10, with Clang branches/release_32 compiled from source in release mode.

Any idea what I should look at next?

Thanks,
Martin

This doesn't look like a clang issue. The condition_variable code is trying to truncate a time_point based on nanoseconds into one based on microseconds, and <chrono> won't let you do that implicitly. This is a bug in the condition_variable code that <chrono> has found at compile time.

Howard

See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53841