November 2013 - Boost - lists.preview.boost.org

More flexible any_cast for boost::any
by DeadMG 28 Nov '13

28 Nov '13

Hello, I've been looking at ABIs and such (various unpleasant reasons). But I recently created the following code: #include <iostream> struct Base { virtual void check() = 0; template<typename T> T* IsDerivedFrom() { try { check(); } catch(T* p) { return p; } catch(...) { return nullptr; } return nullptr; } }; template<typename T> struct Derived : public Base { Derived(T obj) : t(obj) {} T t; void check() override final { throw &t; } }; struct A { virtual ~A() {} virtual void print() = 0;}; struct B : public A { int x; B(int y) : x(y) {} void print() override final { std::cout << x; } }; int main() { Base* b = new Derived<B>(B(5)); A* p = b->IsDerivedFrom<A>(); p->print(); } Whilst this is hardly the cleanest piece of code I've ever written, it also provides a base for implementing a more generic any_cast<ValueType>, which could succeed if ValueType is a base class of the stored type. Amazingly, the Standard requires the code to work but does not provide a cleaner means of implementation. I also note that, for some configurations, you could fall back to the Itanium ABI provided function directly, which would presumably be substantially faster and cleaner. Enabling this variety of any_cast would substantially improve the composability of boost::any. For example, it's arguable that std::function is merely boost::any but with additional interface requirements. With such an any_cast enhancement, it would be quite trivial to compose std::function implementations or similar concepts on top of boost::any.

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Re: [boost] [conversion] Isolating the phantom file changes problem
by Cox, Michael 28 Nov '13

28 Nov '13

In addition to re-normalizing the line endings, we could also start enforcing coding standards, e.g. tabs converted to spaces standard via gitconfig/gitattribute filters. Git allows you to define filters in your .git/config or ~/.gitconfig file and specifying their use in .gitattributes, e.g. in .gitconfig: # Convert tabs to 4 spaces (uses Linux expand/unexpand commands, so not cross-platform) [filter "tabspace"] smudge = unexpand --tabs=4 --first-only clean = expand --tabs=4 --initial Then in .gitattributes: # Code formats *.c text filter=tabspace *.cpp text filter=tabspace *.h text filter=tabspace *.hpp text filter=tabspace *.ipp text filter=tabspace *.tpp text filter=tabspace On a related topic, what is the svneol .gitattribute being used in the .gitattributes file do? I couldn't find it documented (I discovered the filter attribute while searching for the svneol attribute). Also, the mime type specified in a # comment following some attribute rule specification doesn't seem to be a supported syntax, i.e. the '#' has to be in the first column. Michael On Wed, Nov 27, 2013 at 3:02 PM, Gavin Lambert <gavinl(a)compacsort.com>wrote: > On 28/11/2013 05:17, Quoth Dave Abrahams: > > Another possibility might be to explicitly mark all text files in >>> .gitattributes with eol=lf and then run the conversion; I think that >>> would fix the repository blobs, >>> >> >> What goes into .gitattributes has no effect on the content of blobs in >> the repository. >> > > Sorry, when I wrote that I was envisaging the conversion process doing the > equivalent of an SVN checkout and then git add/commit. (And git commit > does take the attributes into account for eol conversion.) > > Since apparently it doesn't work like that, just ignore that suggestion. > > I still think that we need to renormalise the line endings though. Whether > that's done as a reconversion (fixing history) or just as an extra commit > (fixing current heads), that's up to you guys. ;) > > > > > _______________________________________________ > Unsubscribe & other changes: http://lists.boost.org/ > mailman/listinfo.cgi/boost >

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[conversion] Verification check results: svn trunk vs git develop
by Beman Dawes 28 Nov '13

28 Nov '13

* There is an entire library, Boost.Compose, long since deprecated and removed from svn in favor of Boost.Bind or Boost.Lambda, present in the git repos, both in master and develop. * Boost.Interprocess, git develop contains a header libs\include\boost\interprocess\fully_mapped_file.hpp that does not appear in the svn trunk head. * Boost.Type-Traits, git develop contains a header directory, \include\boost\detail, with two header files. Neither these two headers nor the directory are present in svn trunk head. * All 9974 headers in svn trunk/boost head have git super-project boost header entries generated by "b2 headers" and the content, ignoring end of line differences, is identical in all of them. * Exactly the same 5680 regression tests passed for both svn trunk head and git develop head. It doesn't get any better than that! --Beman

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[exception][range] boost/range/size_type.hpp + unexpected dependenciies Exeception -> Units -> Algorithms -> Range -> Concepts
by Vicente J. Botet Escriba 28 Nov '13

28 Nov '13

Hi, The regression test signal this error Test output: MinGW-w64-4.5 jc-bell.com - thread - async__async_p / gcc-mingw-4.5.4 Rev 85699 / Mon, 16 Sep 2013 13:58:07 +0000 Compile [2013-09-16 17:53:55 UTC]:fail "g++" -ftemplate-depth-128 -O0 -fno-inline -Wall -pedantic -g -mthreads -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_CHRONO_DYN_LINK=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_SYSTEM_NO_DEPRECATED -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED -DBOOST_THREAD_USE_DLL=1 -I".." -c -o "F:\boost\GCC\trunk\results\boost\bin.v2\libs\thread\test\async__async_p.test\gcc-mingw-4.5.4\debug\threading-multi\sync\futures\async\async_pass.o" "..\libs\thread\test\sync\futures\async\async_pass.cpp" In file included from ../boost/range/size.hpp:21:0, from ../boost/range/functions.hpp:20, from ../boost/range/iterator_range_core.hpp:28, from ../boost/range/iterator_range.hpp:13, from ../boost/algorithm/string/replace.hpp:16, from ../boost/units/detail/utility.hpp:25, from ../boost/exception/detail/type_info.hpp:19, from ../boost/exception/detail/object_hex_dump.hpp:15, from ../boost/exception/to_string_stub.hpp:16, from ../boost/exception/info.hpp:16, from ../boost/exception/detail/exception_ptr.hpp:20, from ../boost/exception_ptr.hpp:9, from ../boost/thread/future.hpp:28, from ..\libs\thread\test\sync\futures\async\async_pass.cpp:29: ../boost/range/size_type.hpp:80:5: error: expected ';' before '}' token ../boost/range/size_type.hpp:80:5: error: expected ';' before '}' token ../boost/range/size_type.hpp:87:5: error: expected ';' before '}' token ../boost/range/size_type.hpp:87:5: error: expected ';' before '}' token BOOST_RANGE_CONCEPT_ASSERT((boost::SinglePassRangeConcept<T>)) This is surely due to a changeset on Boost.Range (85690?). Maybe an inclusion to Concepts is missing. Could the maintainer take a look? What is more surprising is the chain of dependencies the inclusion of boost/exception_ptr.hpp conveys. Exeception -> Units -> Algorithms -> Range -> Concepts. Is there a way to break these dependencies? Best, Vicente

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Git conversion fixes
by Dave Abrahams 28 Nov '13

28 Nov '13

We have two issues currently extant: 1. Some files that were deleted in SVN history are still present in the Git HEAD 2. Some people are dissatisfied with the way line endings are handled, especially on Windows I didn't expect to spend my Thanksgiving vacation working on this stuff, but I am getting myself set up to diagnose and fix #1. I am not going to try to fix #2, mostly because it's too open-ended, and there isn't even a consensus in the community about what a fix should look like. If a consensus is formed around a desired outcome, I am willing to at _least_ help in an advisory capacity, in which case someone should send me a personal email. Thanks, Dave

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[build] clang-win help needed
by Edward Diener 28 Nov '13

28 Nov '13

The clang-win.jam file, which was provided by 'tr1gun' as an attachment to another thread in Boost Build, inherits its generators, flags, and rules from msvc.jam. The lines in clang-win.jam are: toolset.inherit-generators clang-win <toolset>clang <toolset-clang:platform>win : msvc ; toolset.inherit-flags clang-win : msvc : <debug-symbols>on/<debug-store>object : YLOPTION ; toolset.inherit-rules clang-win : msvc ; In order to eliminate the VC++ /EH(x) option, which clang using VC++ RTL does not use, I added into the file a rule: rule compile.c++ ( targets * : sources * : properties * ) { C++FLAGS on $(targets) = [ set.difference [ on $(targets[1]) return $(C++FLAGS) ] : /EHs ] ; } suggested by Steve Watanabe. This effectively eliminates the /EHs option when compiling with clang. However when a 'run' action is done, with clang as the compiler, the compile step is never called. If I remove the 'rule compile.c++' from the clang-win.jam file the compile step is called before the link and execute steps of the 'run' action, but of course the compile step then issues the /EHs warning which the insertion of the above rule eliminated. Does anybody know why adding the above rule causes the 'run' action to not compile the appropriate fle before attempting the link and execute ?

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Peer Review Report for proposed Boost.TypeIndex v2.1 Nov 12th – 21st 2013
by Niall Douglas 27 Nov '13

27 Nov '13

Please let me know as soon as possible any errata, missing credits etc. Niall Boost Peer Review Report for proposed Boost.TypeIndex v2.1 Nov 12th – 21st 2013 This report is the first edition, dated Sunday 24th November 2013. The review manager was Niall Douglas http://www.nedprod.com/. Source: https://github.com/apolukhin/type_index/zipball/master Documentation: http://apolukhin.github.com/type_index/index.html Peer review discussion detail: http://boost.2283326.n4.nabble.com/TypeIndex-Peer-review-period-for-library… My thanks to the Boost members whose peer review makes up this report: Robert Ramey, Vicente J. Botet Escriba, Gavin Lambert, Andrey Semashev, Steven Watanabe, pfultz2, Mathieu Champlon, Joël Lamotte Klaim, Rob Stewart, Jan Herrmann, Tony Van Eerd. Contents: · Summary of consensus from peer review ......................................................................................................... 1 · My recommendation to the library author and the Review Wizards ................................................................ 3 Summary of consensus from peer review: The consensus feedback was to accept TypeIndex after substantial modifications. There were two recommendations of rejection due to how substantial such modifications would need to be (i.e. a request for a second round of peer review with a new implementation). Note that my personal opinion based on post-review reflection is written in [square bracketed italics]. · Many seemed to feel that a boost::type_info’s member function API, where identically named to that of std::type_info member function API, ought to have identical compile-time effects. This implied that missing member function APIs, or other compile time errors for missing or incomplete functionality, would be okay but if name() returns some const char *, then any const char * so long as it meets the C++ standard is okay. [I think there are three use cases for a type_info like substitute: (i) as a lightest possible weight, non-RTTI requiring minimal type_info which can have any API it likes and ought to not be directly substitutable for std::type_info or std::type_index (ii) as a compile-time substitute for std::type_info in that it will compile without third party code modification, but may not produce reliable code due to not returning exactly the same values as std::type_info (iii) as a runtime substitute for std::type_info in that it will require code to be “ported” to it due to having a breaking API, but thereafter produces reliable code. I’ll be very blunt in saying that (ii) is a bad idea in my opinion, and (iii) is valuable but out of scope enhancement which could be added as a separate class after peer review. In my opinion, (i) is where we ought to focus, and I would recommend that the lightest possible weight type_info replacement be deliberately compile-time incompatible with std::type_info (where output is not identical to std::type_info) to force porting code to it so authors are not lazy.] · A large minority seemed to feel that a boost::type_info’s member function API, where identically named to that of std::type_info member function API, ought to have identical run-time outcomes. Most specifically, this would mean that member functions e.g. name() would return exactly what std::type_info’s name() does, even if for example name() returns a std::string instead of a const char * as would be necessary in pre-C++11 compilers. [This is really use case (iii) in the previous item.] · It was mentioned that it should be possible to optionally specialise std::hash<> for type_info for optional seamless use in hash taking containers. · Some felt that implementation-specific std::type_info quirks ought to be replicated. Others felt they should not, and a portable interface which works identically on all platforms is preferred. [This is really use case (iii) in the previous item.] · boost::type_info is currently initialised via a static cast from a std::type_info when RTTI is available. This is undefined behaviour, and some felt this to be a showstopper. I (Niall Douglas) looked into this more deeply due to its seriousness, and found that because most STL implementations define std::type_info with a virtual function table, the undefined behaviour static cast would cause dynamic_cast on a boost::type_info instance to misoperate. [I believe the RTTI induced misoperation to indeed be a showstopper, and that this use of undefined behaviour to reduce code bloat is an unsafe optimisation. A much lighter weight non-direct-substitute for std::type_info ought to be as code bloat parsimonious as is possible, while its lack of non-explicit interoperation ability with std::type_info ought to allow avoidance of needing any UB tricks.] · Some felt that any use of implied boost::type_info ought to be explicitly written as boost::type_info instead of relying on namespace lookup, as the name similarity to std::type_info may introduce confusion. [I agree] · It was mentioned that some function-local static data members are initialised in a thread unsafe way. [For information I have to hand a very lightweight BOOST_BEGIN_MEMORY_TRANSACTION() implementation ideal for this purpose. We could submit it to Boost.Detail and then everyone could use it?] · Magic macros such as __PRETTY_FUNCTION__ ought to not be referenced outside of a function as they don’t technically exist there. Checks for their existence ought to be within a function. · It was requested that a boost::type_id<> which takes some unknown variable instance as a parameter and therefore allows the compiler to deduce the type of the variable as the boost::type_index<T> type would be valuable. · A mechanism for programming compile-time logic with class inheritance trees such that inheritance can be determined at compile-time with RTTI disabled was requested. My recommendation to the library author and the Review Wizards: · In my opinion Antony ought to make TypeIndex v3 quite literally a very lightweight container of some unknown, but known to be uniquely identifying for some type, static const char * string. I think its class type and its list of member functions ought to be deliberately compile-time incompatible with std::type_info to force authors to upgrade their code. A conversion member function ought to be able to synthesise a corresponding std::type_info using typeid() from some boost::type_index<T>, but that’s about it. I would even, personally speaking, go so far as to only provide a boost::type_index and no corresponding boost::type_info, especially if the boost::type_id<T>() function can return a const boost::type_index<T>& and therefore can be used as a static const lref, or copy constructed from it etc. A suggested name() member function replacement which correctly breaks out the multiple confounding uses of std::type_info::name() into each of their three use cases (and which intentionally causes any use of name() to fail to compile) might be: Text Box: /*! Returns a static const char string of unknown format uniquelyidentifying this type.The only guarantee is that this string will beunique to the type within this process lifetime. */const char *unique_name() const noexcept;/*! Returns a representation of this type suitable for printing.This call may take some time as its storage may not be cached. */std::string pretty_name() const;class enum mangling{Native, //!< Whatever the native mangling used by this toolset isMSVC, //!< The Microsoft C++ mangling formatItanium //!< The Itanium C++ mangling format};/*! Returns the mangled form of the string representation of the type.After the calculation the value is cached statically such that the c_str()function can be used to convert the returned string to a const char *format identical to what may be returned by std::type_info::name() (orraw_name() on MSVC).This function may throw an exception if it does notsupport mangled type string calculation, including when mangling=Native onsome Bear in mind that user code can always subclass boost::type_index and add their own name() implementation based on one or more of the above new member functions. · In other words, here I think “less is more” in every way you look at it. I think a slimmer less heavy TypeIndex would be a superior solution. · I request the Review Wizards to allow Antony some time to make the changes to produce a v3 of the library, and then to allow TypeIndex v3 a Fast Track Review of five days to ensure the Boost community is happy and that its feedback has been incorporated. It was asked during peer review that such a five day period please include a weekend. I would be happy to serve as review manager again if requested. Niall Douglas Waterloo, Canada, November 2013

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[conversion] Verification check results: svn branches/release vs git master
by Beman Dawes 27 Nov '13

27 Nov '13

* As reported previously, the follow extra header files are present in the git repos: > boost\functional\hash\Attic\deque.hpp > boost\functional\hash\Attic\list.hpp > boost\functional\hash\Attic\map.hpp > boost\functional\hash\Attic\pair.hpp > boost\functional\hash\Attic\set.hpp > boost\functional\hash\Attic\vector.hpp > boost\property_tree\detail\exceptions_implementation.hpp > boost\property_tree\detail\path_implementation.hpp > boost\property_tree\detail\pugxml.hpp > boost\property_tree\detail\translator_implementation.hpp > boost\property_tree\detail\xml_parser_read_pugixml.hpp > boost\property_tree\detail\xml_parser_read_pugxml.hpp > boost\property_tree\detail\xml_parser_read_spirit.hpp > boost\property_tree\detail\xml_parser_read_tinyxml.hpp * There were no missing header files in master. * Except for line endings and svn $Id$, $Revision$, and $Date$, there were no differences in content between header files in svn branches/release and git master. * Regression tests were run on both svn branches/release and git master. 5447 tests passed on each, however each had one test that passed on it but failed on the other. See the following two items for details. * Boost.Thread test_thread_lib passed on svn branches/release (and in the public regression tests) but failed on svn master. The message was: ====== BEGIN OUTPUT ====== Running 8 test cases... d:/modular-boost/libs/thread/test/./util.inl(160): fatal error in "test_creation_through_reference_wrapper": Timed test didn't complete in time, possible deadlock. *** 1 failure detected in test suite "Master Test Suite" EXIT STATUS: 201 ====== END OUTPUT ====== Windows decided to go to sleep in the middle of the run, and that may account for this error. * Boost.Thread ex_executor_lib passed in git master, but failed in svn branches/release. The message was: ====== BEGIN OUTPUT ====== 1178 ..\libs\thread\test\..\example\executor.cpp[ 58] int __cdecl main(void) 940 6776 ..\libs\thread\test\..\example\executor.cpp..\libs\thread\test\..\example\executor.cpp[[ 2126] ] void __cdecl p1(void)void __cdecl p2(void) 940 d5c1a78 ..\libs\thread\test\..\example\executor.cpp..\libs\thread\test\..\example\executor.cpp[[ 2121] ] void __cdecl p1(void)void __cdecl p1(void) d5c 1a78 ..\libs\thread\test\..\example\executor.cpp..\libs\thread\test\..\example\executor.cpp[[ 2621] ] void __cdecl p2(void)void __cdecl p1(void) ..\libs\thread\test\..\example\executor.cppd5c [ 1a..\libs\thread\test\..\example\executor.cpp] [void __cdecl p2(void)26 ] void __cdecl p2(void) 940 d5c ..\libs\thread\test\..\example\executor.cpp..\libs\thread\test\..\example\executor.cpp[[ 2126] ] void __cdecl p1(void)void __cdecl p2(void) d5c 940 ..\libs\thread\test\..\example\executor.cpp..\libs\thread\test\..\example\executor.cpp[[ 3131] ] int __cdecl f1(void)int __cdecl f1(void) Assertion failed: 0 && "Boost::Chrono - Internal Error", file C:\boost\svn-release-final\boost/chrono/detail/inlined/win/chrono.hpp, line 44 1178 ..\libs\thread\test\..\example\executor.cpp[ 67] int __cdecl main(void) t1= 1 EXIT STATUS: 3 ====== END OUTPUT ====== I have no idea why it would pass for testers but not for me, but am much less worried about a failure in svn branches/release than git master. --Beman

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[conversion] Serious header integrity test failures.
by Beman Dawes 27 Nov '13

27 Nov '13

This integrity test verifies that every header file present in svn branches/release and trunk is also present in git master and develop, respectively, and visa versa. The branches/release vs master comparison is in pretty good shape - no missing headers, but a small number of extra headers. Two libraries are affected. But the trunk vs develop comparison turned up problems in many libraries. For example, the whole Boost.Chrono stopwatches sub-directory is missing. These look serious. What is the fix? --Beman

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Code to address requirement 7(a) of IOStreams Roadmap
by Gene Panov 26 Nov '13

26 Nov '13

Colleagues, I posted this before, but didn't get answers to some questions so far. I think I addressed the "output" part of requirement 7(a) from the IOStreams Roadmap: https://svn.boost.org/trac/boost/wiki/IostreamsRoadmap in this library: https://code.google.com/p/async-ostream/ Does anyone mind if I create a patch for Boost.IOStreams to add those five files and ask the maintainer (or volunteers) for feedback? Regards, Gene

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