Boost C++ Libraries: Ticket #8367: chrono does not compile with clang from XCode 4.5.2 with -std=c++11 -stdlib=libc++ and -arch armv7

attachment set

Tue, 02 Apr 2013 10:02:21 GMT

attachment → clang_chrono.txt

status, description changed

viboes — Mon, 08 Apr 2013 17:44:33 GMT

status new → assigned
description modified (diff)

The error appears when the standard library doesn't uses constexpr for max()

41	./boost/chrono/duration.hpp:353:49: error: constexpr function never produces a constant expression
42	        static BOOST_CHRONO_LIB_CONSTEXPR float lowest() BOOST_CHRONO_LIB_NOEXCEPT_OR_THROW
43	                                                ^
44	./boost/chrono/duration.hpp:355:21: note: non-constexpr function 'max' cannot be used in a constant expression
45	            return -(std::numeric_limits<float>::max) ();
46	                    ^

BOOST_CHRONO_LIB_CONSTEXPR is defined as follows

#if defined( BOOST_NO_CXX11_NUMERIC_LIMITS )
#define BOOST_CHRONO_LIB_CONSTEXPR
#elif defined(_LIBCPP_VERSION) && _LIBCPP_VERSION < 1002
  #define BOOST_CHRONO_LIB_CONSTEXPR
#else
  #define BOOST_CHRONO_LIB_CONSTEXPR BOOST_CONSTEXPR
#endif

Could you tell me what is the value of BOOST_NO_CXX11_NUMERIC_LIMITS and _LIBCPP_VERSION on the environment you get the error?

Tue, 09 Apr 2013 07:05:15 GMT

BOOST_NO_CXX11_NUMERIC_LIMITS is undefined.

Here's the extract of clangs config file:

#define _LIBCPP_VERSION 1101
#define _LIBCPP_ABI_VERSION 1

The problem is related to the combination of -std=c++11 and -stdlib=libc++. If I use only one of them, everything is fine.

Marshall Clow — Tue, 09 Apr 2013 07:50:39 GMT

This was fixed (by Apple) as part of the Xcode 4.6 release.

Specifically, std::numeric_limits<>::max() is now constexpr.

viboes — Wed, 10 Apr 2013 17:01:29 GMT

Replying to Franz Detro <franz.detro@…>:

BOOST_NO_CXX11_NUMERIC_LIMITS is undefined.

Here's the extract of clangs config file:
#define _LIBCPP_VERSION 1101
#define _LIBCPP_ABI_VERSION 1
The problem is related to the combination of -std=c++11 and -stdlib=libc++. If I use only one of them, everything is fine.

Please could you try the following patch

#if defined( BOOST_NO_CXX11_NUMERIC_LIMITS )
#define BOOST_CHRONO_LIB_CONSTEXPR
#elif defined(_LIBCPP_VERSION) && _LIBCPP_VERSION <= 1101
  #define BOOST_CHRONO_LIB_CONSTEXPR
#else
  #define BOOST_CHRONO_LIB_CONSTEXPR BOOST_CONSTEXPR
#endif

viboes — Wed, 10 Apr 2013 17:02:03 GMT

Replying to marshall:

This was fixed (by Apple) as part of the Xcode 4.6 release.

Specifically, std::numeric_limits<>::max() is now constexpr.

Do you know since which _LIBCPP_VERSION this is fixed?

Marshall Clow — Wed, 10 Apr 2013 20:34:25 GMT

_LIBCPP_VERSION was changed to 1101 soon after std::numeric_limits<>::max() was marked as constexpr.

You can check for that, or use #ifdef _LIBCPP_CONSTEXPR which was added at the same time as the change.

milestone changed

viboes — Thu, 11 Apr 2013 06:00:16 GMT

milestone To Be Determined → Boost 1.54.0

Thanks for the info. Committed revision [83842].

status changed; resolution set

viboes — Sat, 13 Apr 2013 12:56:33 GMT

status assigned → closed
resolution → fixed

(In [83866]) Chrono: merge to fix #8367.