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[test] showtopper for release 1.49 - std::forward not found when compiling with clang 3.0 c++0x mode.
by Vicente J. Botet Escriba 03 Jan '12

03 Jan '12

Hi, I have created a show stopper ticket https://svn.boost.org/trac/boost/ticket/6345 as after updating the trunk, I'm unable to test any library using Boost.Test. Recent modification on Boost.Test make it unusable with clang 3.0 c++0x due to std::forward missing or not found. clang-darwin.compile.c++ ../../../bin.v2/libs/thread/test/test_thread.test/clang-darwin-3.0x/debug/threading-multi/test_thread.o In file included from test_thread.cpp:16: In file included from ../../../boost/test/unit_test.hpp:19: In file included from ../../../boost/test/test_tools.hpp:328: In file included from ../../../boost/test/tools/impl.hpp:25: ../../../boost/test/tools/assertion.hpp:278:21: error: no member named 'forward' in namespace 'std' : m_value( std::forward<T>(val) ) ~~~~~^ ../../../boost/test/tools/assertion.hpp:278:29: error: 'T' does not refer to a value : m_value( std::forward<T>(val) ) ^ The revision is https://svn.boost.org/trac/boost/changeset/75370 #ifndef BOOST_NO_RVALUE_REFERENCES explicit value_expr( T&& val ) : m_value( std::forward<T>(val) ) #else explicit value_expr( T const& val ) : m_value( val ) #endif #ifndef BOOST_NO_RVALUE_REFERENCES operator->*( T&& v ) const { return value_expr<T>( std::forward<T>( v ) ); } #else operator->*( T const& v ) const { return value_expr<T>( v ); } #endif This has as consequence that the authors developing mainly with this compiler and using Boost.Test to be unable to deliver new modifications. I have added #include <utility> without success. I guess that the standard library doesn't provides this function even if the compiler provides rvalue references. The code should test for a macro that states if std::forward is available. Please could someone help on this issue? Best, Vicente

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[Boost.Math] Re: [Monotone-debian] Bug#653764: FTBFS with Boost 1.48: lgamma_small.hpp:483:38: error: expected primary-expression before 'do'
by Steve M. Robbins 02 Jan '12

02 Jan '12

Hello, Boost Developers: I recently did rebuilds of all Debian packages that use Boost with Boost 1.48 and this is one of the casualties of the upgrade (from 1.46.1). On Sat, Dec 31, 2011 at 12:02:37PM +0100, Zack Weinberg wrote: > On Fri, Dec 30, 2011 at 9:53 PM, Steve M. Robbins <smr(a)debian.org> wrote: > > This package failed to build using the newest Boost version 1.48: > ... > > /usr/include/boost/math/special_functions/detail/lgamma_small.hpp: In function 'T boost::math::detail::lgamma_small_imp(T, T, T, const mpl_::int_<0>&, const Policy&, const L&)': > ... > > /usr/include/boost/math/special_functions/detail/lgamma_small.hpp:483:38: error: expected primary-expression before 'do' > > I'm not in a position to verify this for myself for another week, but > I have a horrible feeling I know what's wrong: Monotone defines > several one-character macros for its own use, and L() is one of them. > It looks like Boost is using L() for its own purposes and expecting it > not to be a macro. Zack, you are absolutely right. The lgamma_small header has a templated class method using "L" as one of the templates: template <class T, class Policy, class L> T lgamma_small_imp(T z, T zm1, T zm2, const mpl::int_<0>&, const Policy& pol, const L&) The compile error at line 483 is at a call to L(): result = log(gamma_imp(z, pol, L())); > I'd argue that Boost headers should take care to defend themselves > from the possibility of such macros, but fixing that in Boost might be > an enormous amount of work, and in any case, 1.48 is already out > there. Boost.Math developers: What is the right thing to do here? More descriptive class template parameters? Attached is a trivial file to reproduce the bug. Thanks, -Steve

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boost modularisation status?
by Robert Ramey 02 Jan '12

02 Jan '12

https://svn.boost.org/trac/boost/wiki/CMakeModularizationStatus hasn't been modified in 3 years. Also, when I peruse my local copy of the release tree, I don't see what I expect to see according to https://svn.boost.org/trac/boost/wiki/CMakeModularizeLibrary That is, I expect to seem include inside of the libraries at boost/libs/tr1/include - I don't see this. What is the current status of this? Robert Ramey

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[review] Boost.Context mini-review starts today, January 2nd
by Giovanni Piero Deretta 02 Jan '12

02 Jan '12

Hi all, we will start a new year of Boost reviews with a one week mini-review of the Boost.Context library of Oliver Kowalke. The review period starts today January 2nd and ends January 11. Please use [context review] as prefix of your post. Reviewers are strongly encouraged to send their reviews to the boost development mailing list as this is the I follow more assiduously. Please note that Boost.Context was already reviewed and conditionally accepted last May, so we are not voting for acceptance. Instead, this mini-review is to discuss whether the library meets the conditions on acceptance that were listed by Vicente Botet, the review manager at that time. You'll find the whole list at the end of this email. Since the end of the original review, Oliver has spent a large amount of time on a partial rewrite of the library and both me and Oliver decided to schedule this review only after we determined that all issues had been addressed or at least considered. In your review please state whether the acceptance conditions have been addressed satisfactorily. ---------------------------------------------------------------------------------- About the library: Boost.Context is a foundational library that provides a sort of cooperative multitasking on a single thread. By providing an abstraction of the current execution state in the current thread, including the stack (with local variables) and stack pointer, all registers and CPU flags, and the instruction pointer, a context instance represents a specific point in the application's execution path. This is useful for building higher-level abstractions, like coroutines and fibers. ---------------------------------------------------------------------------------- Useful Links: documentation: http://ok73.ok.funpic.de/boost/libs/context/doc/html/ library: git://github.com/olk/boost.context.git ---------------------------------------------------------------------------------- >From the original review result email: Point to be addressed before the mini review: Design 1. Separation of the context class in two interface: - A C-like interface that defines a POD struct that is memcpy-able and that can be implemented either using platform libraries, as ucontext, fibers or directly using assembler when a robust implementation is available. The context swap implementation don't need to save the signals as ucontext does. The following is just for illustrations purposes. struct boost_context; typedef void boost_context_fn_t(intptr_t); extern "C" void boost_context_make(boost_context* ctx, boost_context_fn_t * f, intptr_t p, ...); extern "C" void boost_context_swap(boost_context* from, boost_context const* to); extern "C" intptr_t boost_context_destroy( boost_context* fc); boost_context_make is a merge of get_context with make_context + some fields assignations. "A user will have lower expectations from such a low level API and at the same time will give more freedom for other people to implement on top of it higher abstractions as Boost.Corutines, Boost.Fibers ..." - A non-copiable but movable safe context class on top of the low level C-like interface, that will provide modern and efficient C++ interface, that is usable by a user in a safe way. The safe context class would just be one of the client of the C-like interface, other library authors could either use the underlying C-like API directly or the class context depending on wether they need the speed or safety. * The context class will not be templated any more, and the use of type erasure will ensure that. * The constructor will accept any C++ callable, function pointers, functors, ... * At this high level interface, the function provided by the user could throw exceptions, and the library must wrap the user function and needs to store the exception raised and provide an interface to retrieve them. 2. The stack implementation must ensure that the stack is unwound before it is destroyed. A stack should only be safely deallocated if either has been completely unwound or if it doesn't own any resources. A basic stack without protection seems mandatory. For debug purposes it has been required to provide some stack usage functions that allow to know the max size used for example. Implementation 3. The assembler implementation on Windows must be disallowed if the ABI bug reported by Holger is confirmed. As far as Windows provides a fiber implementation that is as efficient as the assembler one, the assembler implementation is not mandatory and the user of the provided Windows fiber is a preferable choice. 4. Most of the 'throw' statements in the context class should actually be asserts. 5. The provided stack should be used to store any context parameters as far as no major impediment is found during the implementation. This will avoid further allocations on the safe context class. Documentation 6. The documentation is very minimalist and should be expanded with a discussion on context switching and use cases. Take care of all the grammar/spelling improvements suggested by the reviewers (It will be great if Jeffrey could review the documentation before the mini-review). Some user land examples should be provided (why not the yield example). 7. The concept of (Movable) Stack must be clearly defined, as it is done in the standard, using expression requirements with semantic constraints. 8. The assembler implementation should be carefully documented, so others could maintain the code and add other implementations if needed. 9. Some performance measure should be added. Providing the number of cycles on each implemented platform would be nice. Build system 10. The default build on a platform must work (It must be ABI compatible with the underlying platform) and take care of the specific features. Of course, the build needs to support cross compiling, so the user should be able to override the default values. Others points that are not required but that can make the library more usable or efficient: 1. The assembler implementations could be simplified if the context itself was represented as a single pointer to the top of the stack. This would save some instructions to move the source address from the stack return address to the context struct and back. 2. Instead of supporting a 'fc_link' a-la ucontext, have the callback function return a new context (it is void now). 'fc_link' is useful only on some limited cases (usually when you have an external scheduler managing your contexts), while the having the callback return the 'next continuation' has more applications (note that fc_link can be implemented easily in term of the continuation returning variant, but the reverse is harder). This will be very useful, for example, to implement some kind of 'exit_to' functionality (unwind the stack and restore another context), a key piece for safe context destruction. 3. Give to boost_context_swap the ability to exchange a parameter with the other context: boost_context_parm_t boost_context_swap( boost_context * ofc, boost_context const* nfc, boost_context_parm_t parm) where boost_context_parm_t is either union boost_context_parm_t { void * ptr; int int_; }; or simply intptr_t; boost_context_swap saves the current context in ocf and restores the context ncf as usual; additionally, if ofc was 'captured' on a call to boost_context_swap, this call will return the value of parm on the original context. This extra parameter is equivalent to the second parameter of longjmp. If ofc was created with boost_context_swap, 'parm' will be an extra parameter to the function. Note that this can be potentially implemented with little or no overhead. 4. Add a variant of boost_context_swap that allows executing a function on the destination context (in this case 'parm' would be passed parameter to this function. This is mostly useful for injecting an exception on the destination context. This can be potentially implemented on top of the existing functionality, but would slow down every context switch; a possible efficient implementation would manipulate the destination stack to add a call to the function on top of it, so that the cost is paid only when required. 5. Add a current context function (thread local).

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[Graph] LEDA adapter - concept check VertexListGraph fails
by Jens Müller 01 Jan '12

01 Jan '12

Hi everyone, when running the tests for Graph, the first concept check in leda_graph_cc.cpp fails: gcc.compile.c++ ../../../bin.v2/libs/graph/test/leda_graph_cc.test/gcc-4.6.1/debug/leda_graph_cc.o In file included from leda_graph_cc.cpp:9:0: ../../../boost/graph/graph_concepts.hpp: In destructor 'boost::concepts::VertexListGraph<G>::~VertexListGraph() [with G = leda::GRAPH<int, int>]': ../../../boost/graph/graph_concepts.hpp:168:1: instantiated from 'static void boost::concepts::requirement<boost::concepts::failed************ Model::************>::failed() [with Model = boost::concepts::VertexListGraphConcept<leda::GRAPH<int, int> >]' leda_graph_cc.cpp:21:5: instantiated from here ../../../boost/graph/graph_concepts.hpp:189:9: error: no matching function for call to 'vertices(leda::GRAPH<int, int>&)' ../../../boost/graph/graph_concepts.hpp:189:9: note: candidate is: ../../../boost/graph/graph_concepts.hpp:45:48: note: template<class T> typename T::ThereReallyIsNoMemberByThisNameInT boost::vertices(const T&) (among some further errors, but I'd like to ask just about this one now) Apparently it cannot find a vertices() function: ../../../boost/graph/graph_concepts.hpp:189:9: error: no matching function for call to 'vertices(leda::GRAPH<int, int>&)' But there is one in leda_graph.hpp: template <class vtype, class etype> inline std::pair< typename graph_traits< leda::GRAPH<vtype,etype> >::vertex_iterator, typename graph_traits< leda::GRAPH<vtype,etype> >::vertex_iterator > vertices(const leda::GRAPH<vtype,etype>& g) { typedef typename graph_traits< leda::GRAPH<vtype,etype> >::vertex_iterator Iter; return std::make_pair( Iter(g.first_node(),&g), Iter(0,&g) ); } So, can someone enlighten me why it isn't found? Has it something to do with #ifdef BOOST_VECTOR_AS_GRAPH_GRAPH_ADL_HACK // dwa 2003/7/11 -- This clearly shouldn't be necessary, but if // you want to use vector_as_graph, it is! I'm sure the graph // library leaves these out all over the place. Probably a // redesign involving specializing a template with a static // member function is in order :( using boost::vertices; #endif ? Best regards, Jens

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Many Boost.Test unit tests fail
by Barend Gehrels 01 Jan '12

01 Jan '12

Hi, Since today or yesterday, many regression tests fail. http://www.boost.org/development/tests/trunk/developer/summary.html I believe on platforms that are recently added, at last on platforms that were not present at December 17. 1) on clang/darwin, message ../boost/test/tools/assertion.hpp:278:21: error: no member named 'forward' in namespace 'std' 2) on clang/linux, message /usr/bin/ld: skipping incompatible /sierra/Sntools/extras/compilers/gcc-4.4.4/lib/libstdc++.so when searching for -lstdc++ We have these errors in Boost.Geometry but I also noticed them in many other libraries. Regards, Barend

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[filesystem] path thread safety fix impact on POSIX systems
by Beman Dawes 01 Jan '12

01 Jan '12

Class path locale initialization has suffered from a data race for several releases. See https://svn.boost.org/trac/boost/ticket/6320 for an example of code that suffers as a result. The problem was introduced when locale initialization was changed from namespace scope initialization to function scope initialization. For Windows and Mac OS X, the fix is simply to change back to namespace scope initialization. For non-BSD based POSIX systems such as Linux, the problem is more complex. These system need std::locale(""), "the locale-specific native environment". Considerations: * std::locale("") will throw if environmental variables are configured incorrectly. For example, setting LANG=foo on my Ubuntu system causes std::locale("") to throw. * std::locale("") is only needed if conversions between wide and narrow character paths occur in the program, so it would be unfortunate to have programs throw that don't actually do any such conversion. * With GCC, std::locale("") at namespace scope will throw before main() has started! That prevents catching the exception in the user code, and was what led to moving the initialization to a function scope static. Initialization as a function scope static also meant that the exception only occurred if user code actually performed wide - narrow conversions. I can see two possible fixes: (A) Use function scope locale initialization, using boost/detail/lightweight_mutex.hpp to prevent data races. (B) Use namespace scope locale initialization, defaulting the codecvt facet to UTF-8 if std::locale("") throws. The advantage of (B) is that path always initializes without throwing, and that's what users seem to expect. The initialization is correct for all those whose environments are configured correctly, and for those uses who want UTF-8 even if their environments are misconfigured. The POSIX users who prefer an exception on a misconfigured environment can always add a std::locale("") at the start of main(). Comments or opinions? --Beman

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Re: [boost] matrix and vector iterators
by Larry Evans 31 Dec '11

31 Dec '11

On 06/12/01 14:50, David Abrahams wrote: > > ----- Original Message ----- > From: "Larry Evans" <jcampbell3(a)prodigy.net> > > >> David Abrahams wrote: >> >>> One problem with this is that it requires much more of the iterator in > some >>> cases than it otherwise might. In an array stored as vectors of vectors >>> of... vectors, each iterator would need to have references to all of the >>> containing vectors. >> >> Couldn't the iterator just contain a vector of indices of length == rank, >> and a pointer to the vector of vectors of... vectors (VofV), and then just > index into >> the VofV with the vector of indices. > > When you start talking about iterators containing vectors, I get worried. > >> I guess bad thing about that is that it takes longer. > > That's putting it mildly. Iterators should be lightweight. > > -Dave > > Another type of iterator which essentially flattens a multi-dimensional array and *may* be more lightweight is implemented here: http://svn.boost.org/svn/boost/sandbox/variadic_templates/sandbox/stepper/b… and demonstrated here: http://svn.boost.org/svn/boost/sandbox/variadic_templates/sandbox/stepper/l… A more realistic demonstration is in the Partial Differential Equation example here: http://svn.boost.org/svn/boost/sandbox/variadic_templates/sandbox/stepper/l… which uses an axes rotation feature that, IIUC, was requested by Petros here: http://article.gmane.org/gmane.comp.lib.boost.user/68017 Its also used here: http://svn.boost.org/svn/boost/sandbox/variadic_templates/sandbox/stepper/l… which is probably a bit easier to follow than the array_dyn.diff_pde.cpp one ;) I've done no benchmarks; hence, I can't say how lightweight it is; however, since all it does is keep a stack of indices in a data structure instead of on the stack, I would think it wouldn't be that much more heavyweight than simply a nested for loop nested N deep where N is the array dimensionality. BTW, Petros, in a private email to me, has indicated he has some other method for solving the rotated axes problem; however, I've no idea if that's more or less lightweight than this one. -regards, Larry I've run no benchmarks to show how lightweight it may be. Petros, in a private email to me, says he has another way of

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Re: [boost] Comparison of serialization results
by Brian Wood 31 Dec '11

31 Dec '11

Dave Abrahams: > > No post-hock marshalling? You should be able to add marshalling to a > class without modifying its declaration. > If a class is popular enough, I often do. For example, the C++ Middleware Writer (CMW) has support for the standard containers, std::complex, multi_index_container, stable_vector and others. [...] > > No argument; I'm just sayin'. I don't have to go to any great lengths to find tests where the performance of executables that use Boost Serialization lags behind CMW based executables. I just think up a test and write it. The tests are quite basic. > > That's a fundamentally intrusive design; being able to add serialization > non-intrusively was a major design goal for Boost.Serialization. I see. One thing I didn't mention yesterday is support for stream- based constructors: class Base { template <typename R> explicit Base (ReceiveBufferFile<R>& buf); ... }; Does the Boost Serialization library have support for that? Cheers, Brian Wood Ebenezer Enterprises http://webEbenezer.net

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Boost.Pool lost singleton_default -- replacement?
by Steve M. Robbins 31 Dec '11

31 Dec '11

Hi, Prior to 1.48, Boost.Pool's singleton_pool class used a helper class singleton_default. This was hidden in a detail header <boost/pool/detail/singleton.hpp>, yet I found 3 programs in the Debian distribution that used it directly to instantiate their own singletons. I didn't find any direct replacement for singleton.hpp in Boost 1.48. Is there any plan to introduce this later? Thanks, -Steve

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