c++ - std::this_thread::sleep_for() and GCC

Question

When I try to compile this simple program:

#include<thread>

void f() {
  std::this_thread::sleep_for(std::chrono::seconds(3));
}

int main() {
  std::thread t(f);
  t.join();
}

with gcc version 4.4.3 on Ubuntu 10.04 (32 bit):

$ g++ -std=c++0x -pthread a.cpp -o a

I get:

error: ‘sleep_for’ is not a member of ‘std::this_thread’

I looked in header 'thread'.
sleep_for() is protected with _GLIBCXX_USE_NANOSLEEP

#ifdef _GLIBCXX_USE_NANOSLEEP
...
/// sleep_for
template<typename _Rep, typename _Period>
  inline void
  sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
...

Why is _GLIBCXX_USE_NANOSLEEP not defined?
How do I get this example to compile?

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Update 17 Sep 2012 (jogojapan): I ran into this same problem today, using GCC 4.7.1. I wonder if there is any news on how to avoid it, other than by defining _GLIBCXX_USE_NANOSLEEP. I tried using -std=gnu11, but to no avail.

There is also an old, unresolved bug report for GCC 4.4: https://bugs.launchpad.net/ubuntu/+source/gcc-4.4/+bug/608145

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Update 19 Oct 2012 (jogojapan): The issue has now been explained and resolved by Jonathan Wakely as an anwer to this question: What is _GLIBCXX_USE_NANOSLEEP all about? This is particularly relevant for anyone who builds GCC himself instead of using a ready-made package.

Answer 1

Confirmed that it doesn't work here as well. (Recent GCC 4.6 snapshot).

You could do the obvious and simply define it before you include any std:: headers. A bit dirty but will work until GCC fixes it (unless this is intended behavior). The #define shouldn't break anything anyways. Either in source or -D_GLIBCXX_USE_NANOSLEEP flag to GCC.

You might want to try using -std=gnu++0x rather than -std=c++0x, since gnu++0x often pulls in stuff like this.