- Boost - lists.boost.org

[Endian] Reading/writing from/to byte buffers
by Olaf van der Spek 10 Mar '17

10 Mar '17

Hi, One often needs to read or write values from/to a buffer while having a pointer. Could you support this? I guess one could use *reinterpret_cast<big_int64_buf_t&>(*p) but I think functions would be more convenient. On second guess one probably has to use memcpy rather then reinterpret_cast. The functions are probably implemented already but aren't exposed. https://github.com/boostorg/endian/issues/17 -- Olaf

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Fw: Build failed: smart_ptr 1.0.81-develop
by Peter Dimov 10 Mar '17

10 Mar '17

AppVeyor says that bootstrap.bat is broken: bootstrap Building Boost.Build engine ****** B A T C H R E C U R S I O N exceeds STACK limits ****** Recursion Count=509, Stack Usage=90 percent ****** B A T C H PROCESSING IS A B O R T E D ****** Command exited with code 255 -----Original Message----- From: AppVeyor Sent: Friday, March 10, 2017 17:22 To: pdimov(a)pdimov.com Subject: Build failed: smart_ptr 1.0.81-develop Build smart_ptr 1.0.81-develop failed Commit fac6fbe3cf by Glen Fernandes on 3/10/2017 3:21 PM: Update documentation in make_shared_array.html Configure your notification preferences

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[regression dashboard] missing tests
by Raffi Enficiaud 10 Mar '17

10 Mar '17

Hi all, The regression dashboard is truncated, I should see many more tests here: http://www.boost.org/development/tests/develop/developer/test.html at least as many as for the master branch: http://www.boost.org/development/tests/master/developer/test.html Any idea? Raffi

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[stacktrace] review
by Artyom Beilis 10 Mar '17

10 Mar '17

Hello, This is my review of stacktrace library: Note that I have experience with the subject as I developed a similar library for the CppCMS framework [1] > - What is your evaluation of the design? > The design is straight forward and I don't see any major issues with the API. Also I have several suggestions in handling backtrace with catch from } catch (const traced& e) { std::cerr << e.what() << '\n'; if (e.trace) { std::cerr << "Backtrace:\n" << e.trace << '\n'; } } catch (const std::exception& e) { std::cerr << e.what() << '\n'; } In my library I use much simpler approach in terms of API [2] catch(std::exception const &e) { std::cerr << e.what() << std::endl; std::cerr << booster::trace(e); } Where booster::trace is a manipulator that prints strack trace if "e" contains backtrace information - much shorted code without additional catch. I find it very easy to use. Just a suggestion. I also like with_trace templated class idea. > - What is your evaluation of the implementation? Most of my > personal concerns with this library are with the implementation and I > would hugely appreciate feedback from others with substantial > experience of using stacktracing "in anger" in non-trivial use case > scenarios. I mostly reviewed the backend. Linux: ========= 1st of all: I recommend mentioning in the documentation the option -rdynamic/-export-dynamic as otherwise dladdr would likely to fail - it is critical as many may miss one. Regarding use of add2line utility: 1. Failing to calling an external program in case of dladdr fails is bad idea. This behaviour is unexpected by the user. I understand the advantage of this as you can use debug information but should be done only per user specific request (i.e. compilation option) and not by default. 2. If you call add2line - use it for ALL addresses in backtrace at once and not for each single one! My recommendation is to provide alternative backed that uses other way to extract information not involving forking. Maybe try to analyze debug data or so - or require preparing initial map using nm tool and than loading it from file or something like that. Additionally calling the backed linux is bad - as same approach with slight modifications works on *BSD, Mac OS X and Solaris (RIP). Windows: ======== I have a question why you used COM instead of SymFromAddr functions? I understand thread safety issues but simple mutex can solve them. My concerns are regarding MinGW compilers. Have you tested it on MinGW compiler? It wouldn't work as it used MSVC debug information in general so maybe it is good idea to provide an alternative backend that extracts only address and DLL name so you can analyse the stacktrace later (using addr2line utility for example) Take a look on my code [1] regarding non-msvc windows compilers - it provides at least some useful information. > - What is your evaluation of the documentation? The documentation is ok in general and straight forward as the library itself. What I do lack is the documentation of underlying backends - how do they work. 1. use of -rdynamic/-export-dynamic should be noted in "bold face" regarding the use of the library. 2. please do not call it "POSIX backend" - as there none of the stuff you use is actually POSIX... Also you'll probably need different backends for MINGW and mention it. > - What is your evaluation of the potential usefulness of the > library? Very Very useful. > - Did you try to use the library? With what compiler? Did you have any problems? No I didn't - I mostly read the documentation and the backend code. > - How much effort did you put into your evaluation? A glance? A > quick reading? In-depth study? 3-4 hours > - Are you knowledgeable about the problem domain? Yes I am. I have written similar library for CppCMS project [1] - FINAL VOTE: Yes, Conditionally Conditions: Use of addr2line must not be enabled by default. [1] https://sourceforge.net/p/cppcms/code/HEAD/tree/framework/trunk/booster/boo… https://sourceforge.net/p/cppcms/code/HEAD/tree/framework/trunk/booster/lib… [2] https://sourceforge.net/p/cppcms/code/HEAD/tree/framework/trunk/booster/boo… Best Regards, Artyom Beilis

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boost::asio::ssl::stream handshake hang up in reconnection
by jupiter 09 Mar '17

09 Mar '17

Hi, I am running boost socket communication on Debian 8, the following client code works fine when it connected to the server the first time. s.lowest_layer().connect(*endpoint_iterator++, error); s.handshake(boost::asio::ssl::stream_base::client, error); But when the server connection lost, the client would try to run above code repeatedly until the server connection was resumed, the it passed the first line of s.lowest_layer().connect without error, but the it stuck at s.handshake(boost::asio::ssl::stream_base::client, error), the handshake hang up. What I could be missing here? Thank you.

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[preprocessing] Feedback requested on a C99 preprocessor written in pure universal Python
by Niall Douglas 09 Mar '17

09 Mar '17

Those of you who watch reddit/r/cpp will know I've been working for the past month on a pure Python implementation of a C99 conforming preprocessor. I am pleased to be able to ask for Boost feedback on a fairly high quality implementation: https://github.com/ned14/pcpp It passes the C11 standard's list of "tricky" preprocessor expansions and the mcpp test suite. It has no issue correctly handling the preprocessor metaprogramming I've thrown at it from my Boost libraries. I'm not going to claim it can handle Boost.Preprocessor or especially Boost.VMD and I've tried neither, but pull requests with source code fixes adding support for those (with accompanying unit tests) would be welcome. My main use case for writing this is to assemble my header only Boost libraries into a single "drop in and go" file. To that end it has a (still buggy) --passthru mode which passes through #define and #undef plus any #if logic which uses an undefined macro. I'm still working on pass through mode so expect showstopper bugs in that configuration, but as a straight highly standards conforming preprocessor it's ready for others to use and I welcome any feedback. There are a multitude of use cases, everything from running as a conforming preprocessor before invoking MSVC to compile right through to parsing, reflection and introspection of source code. (and yes it is also a Python library as well as a command line tool, you can find API reference docs at https://ned14.github.io/pcpp/) I look forward to any feedback and my thanks in advance for it. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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[regression runner] Preference libstdc++ vs. libc++
by Tom Kent 09 Mar '17

09 Mar '17

I have a bunch of linux regression runners that are executing clang runs of the boost regression suite (clang 3.0 - 4.0), currently these are all using the default, GCC libstdc++. Is there an interest from developers to see these runs with libc++? The basic options: 1) Convert all compatible clang builds to libc++, don't mess with libstdc++ & clang. 2) Duplicate all the clang builds to build each version with both (acknowledging that will add nearly 1/3 to the already large ~125 linux runs). 3) Change most of the runs, but keep a few token libstdc++ & clang runs, with the latest compiler version (what c++ standard c++14? c++1z?). 4) Just add a few token libc++ runs, with the latest compiler version (what c++ standard c++14? c++1z?). 5) Don't add libc++. For background (you can respond to one of the above preferences without reading on), there are two machines constantly running linux builds (in addition to the two windows ones) that I manage. One I consider the "full" suite of compilers. It runs clang 3.0 - 4.0 and gcc 4.4 - 6. For the oldest and latest releas (gcc 4.4, gcc 6, clang 3.0, clang 3.9), I run all the supported standard configs I could find (c++98, c++0x, gnu98, gnu0x -- c++03, c++11, c++14, c++1z and their gnu equivalents). I also do runs with optimization and warnings cranked, against the latest standard config e.g. "-std=c++1z -O2". For all the compiler versions that aren't on the endcaps, I just run a single config with whatever was the latest standard config for that compiler (e.g. gcc-4.8 with c++1y). This is all repeated for develop and master for a total of about 100 different configurations. The machine I consider the "fast results" machine is configured with only four runs, one each for the latest release of gcc and clang with the latest supported standard config (currently gcc-6 1z and clang-3.9 1z), for both master and develop. The goal here is that for any change checked in, the author will have feedback on its success against something modern and relevant within just a few hours. As a backup to the "fast results" machine, I also run those four regression modern runs, interspersed with the rest of the configs every dozen or so runs, bringing the total number of runs on the "full" machine up to around 125, which takes about a week for the machine to get through all the configurations. You can see more details about all of this on the github page where I keep my regression build scripts: https://github.com/teeks99/boost-build/tree/master/Regression The actual confgs run by the "full": https://github.com/teeks99/boost-build/blob/master/ Regression/teeks99-02/machine_vars.json The docker builds for all these machine configurations are kept at: https://github.com/teeks99/boost-build/tree/master/Docker And can be pulled from the docker hub with e.g. `docker pull teeks99/boost-build:clang-3.9` If you've read this far, I'd be happy for any other opinions from developers who use the test matrix. Is it worth keeping all those compilers in the middle? Do we need to test the latest compilers with all the different standard configs (03, 11, 14, 1z + gnu equivalents)? Thanks, Tom

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[safe numerics] comment
by Robert Ramey 09 Mar '17

09 Mar '17

I'm re-posting Vicente's message which apparently got lost in a server issue so we can respond to it. Robert Ramey Hi, let me start with some comments and questions. I was wondering if the requirements of Numeric don't need some kind of conversions between other numeric types. https://htmlpreview.github.io/?https://raw.githubusercontent.com/robertrame… T(u) T{u} How can you implement the conversion from safe<U> to T if you can not convert from U to T? We have implicit conversion from T to Safe and from Safe to T template<class T> constexpr /*explicit*/ safe_base(const T & t); template< class R, typename std::enable_if< !boost::numeric::is_safe<R>::value, int >::type = 0 > constexpr operator R () const; constexpr operator Stored () const; I believed that the conversion from Safe to T needed to be explicit. Having implicit conversion in both directions is suspect. Why the explicit conversion between safe<T> and safe<U> are not allowed when T and U are not the same? IMO, safe_base<T> is either not trivial default constructible and we check the validity of 0, if we don't check it, we should declare it =default. The current definition doesn't adds nothing and makes the type a non-POD and non trivial_default_constructible, which forbids its use on binary messages. constexpr explicit safe_base() { // this permits creating of invalid instances. This is inline // with C++ built-in but violates the premises of the whole library // choice are: // do nothing - violates premise of he library that all safe objects // are valid // initialize to valid value - violates C++ behavior of types. // add "initialized" flag. Preserves fixes the above, but doubles // "overhead" // still pending on this. } I'll suggest to use constexpr safe_base() = default; BTW, why the default constructor is declared explicit? As you say, could we talk of safe<short> when we can have one uninitialized? I believe this needs to appear clearly on the documentation if not already in. Has safe<const T> a sense? Integer<T> are not traits as there is a compiler error when T is not an integer :( template <class T> class Integer : public Numeric<T> { // integer types must have the corresponding numeric trait. static_assert( std::numeric_limits<T>::is_integer, "Fails to fulfill requirements for an integer type" ); }; The same for Numeric. Have you considered to define traits (usable with SFINAE)? I don't see a concept SafeNumeric. Have you considerd it? BTW, these concept classes check only for a single requirement. Shouldn't you specialize numeric_limits lowest()? Have you considered to define basic algorithms managing with the valid conversion between Numeric with the different policies, as Lawrence Crowl is proposing for the standard? http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0103r1.html http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0105r1.html I find weird the way you are including the files #include "concept/integer.hpp" #include "concept/exception_policy.hpp" #include "concept/promotion_policy.hpp" #include "safe_common.hpp" #include "exception_policies.hpp" #include "boost/concept/assert.hpp" I believed we used to inlcude boost files using <> and the absolute path. Is this a good practice? Does it allows the compiler to perform better? Best, Vicente

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Regarding Mentor
by Shaunak Dixit 08 Mar '17

08 Mar '17

Hi I have joined the Boost Developer's mailing list please help me how to find a mentor. thanks you

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[gsoc17] Project1: Static map: Can I implement the competency test in g++-7?
by Vic Luo 07 Mar '17

07 Mar '17

Hi, I'm Zheng Luo, a third-year undergraduate from Shanghai Jiaotong University who have special interest in C++ programming(especially for templates). This is my second year of applying Google Summer of Code and I'm willing to contribute to Static Map project mentioned on SoC2017 page. Previously I worked for a company as a C++ intern for months on Chromium-related projects where I gained some experience about C++ in industry. And my question is, am I allowed to implement the competency test of static_map in g++-7? I have just implemented my own version of static_map which supports the following operations: constexpr StaticMap<int, const char *, 3> m(make_pair(2, "abc"), make_pair(4, "def"), make_pair(6, "ghi")); if (!m[4]) abort(); const char *foo = m[2]; return 0; which is compiled into assembly as: main: xorl %eax, %eax ret under g++-7 with -std=c++1z -O3 So I was wondering did I pass the test? Thanks, -- --------------------------------- Vic Luo Shanghai Jiaotong University Key fingerprint 0x98809ca08bf5662a

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