October 2017 - Boost - lists.preview.boost.org

[timer][msvc] Universal-Windows advice needed
by Beman Dawes 23 Oct '17

23 Oct '17

Pull request https://github.com/boostorg/timer/pull/3 is a fix for Universal-Windows: "universal-windows: GetProcessTimes is not supported". Does anyone have a clue whether the P/R is correct and the best solution? Is the stated problem a temporary one that Microsoft will likely fix, and will it likely be a permanent limitation? Thanks, --Beman

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[system] Header-only Boost.System by default ?
by Damien Buhl 23 Oct '17

23 Oct '17

Dear Boost, Is there any reason why Boost system couldn't be set to be header only by default ? Defining both macros allows it : - BOOST_SYSTEM_NO_DEPRECATED - BOOST_ERROR_CODE_HEADER_ONLY This ease, speeds up and reduces binary size greatly, that it's sad that non-aware Boost User needs to link to some dll/so/dylib of Boost.System per default. It has been in many releases of Boost, wouldn't it be good to set it to be the default for a next release ? Cheers, -- Damien Buhl Software Developer +33 6 77 43 10 05

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[BoostBook] how to automatically test code examples?
by Hans Dembinski 19 Oct '17

19 Oct '17

Hi everyone, I am using BoostBook to prepare the documentation for the proposed histogram library https://github.com/HDembinski/histogram I have written a good deal of the documentation already, and it compiles fine with bjam (thanks to Klemens who showed me how). It says in the BoostBook documentation http://www.boost.org/doc/libs/1_65_1/doc/html/boostbook.html "The BoostBook format allows testcases to be generated by weaving together program fragments from example programs in the documentation. This capability is integrated with testsuite generation so that example programs are normal tests in BoostBook." That's awesome, I would love to use this feature, but the documentation is not explaining how to actually do that. I found the element "testsuite" which probably does what I want. I went on to scan the Boost repository for this BoostBook element, but couldn't find an example to copy from. Could someone help me out? How do I modify my BoostBook and Jam files to generate tests out of the code examples in the documentation? Best regards, Hans

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[msvc] #warning preprocessor directive
by Beman Dawes 17 Oct '17

17 Oct '17

I find it very irritating that VC++ does not support #warning, and have opened a feature request: https://visualstudio.uservoice.com/forums/121579-visual-studio?query=Add%20… The last time #warning was suggested it was rejected because not enough people voted for it. So please consider upvoting it on the above link. The lack of #warning affects Boost libraries in that developers avoid otherwise useful warnings because of the hassle for using an extension not supported by VC++. --Beman

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Merged #149, "Encode architecture and address model in versioned layout names"
by Peter Dimov 17 Oct '17

17 Oct '17

I've just merged https://github.com/boostorg/boost/pull/149, "Encode architecture and address model in versioned layout names", into the develop branch. Let's see how this goes. Welcome to 2005. :-)

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How to build boost on windows with Clang/LLVM
by degski 17 Oct '17

17 Oct '17

With the latest snapshot builds of clang, thin LTO is supported on Windows. This thin LTO gives very interesting (speed) results. I would therefore like to start to build boost with clang and no longer with msvc. I have msvc 15.4 installed (the latest incarnation). I made a project-config.jam: =============start=============== import option ; using clang : 6.0 : clang++.exe : <cxxflags>-fmacro-backtrace-limit=0 <cxxflags>-Wno-invalid-token-paste <compileflags>-fmsc-version=1911 <linkflags>-fuse-ld=lld <linkflags>-flto=thin ; option.set keep-going : false ; ==============end=============== I call: bjam -a -d+2 cxxflags="-O0" "-sZLIB_SOURCE=%HOME%\zlib-1.2.8" "-sBZIP2_SOURCE=%HOME%\bzip2-1.0.6" variant=debug instruction-set=haswell threading=multi link=static runtime-link=static --prefix=%PREFIX% --build-dir=c:\boost-build address-model=64 architecture=x86 toolset=msvc --without-python --without-mpi --disable-filesystem2 install This does not work. What is the proper way to compile boost on windows using clang++.exe or clang-cl.exe for use with VS2017. degski -- "*Ihre sogenannte Religion wirkt bloß wie ein Opiat reizend, betäubend, Schmerzen aus Schwäche stillend.*" - Novalis 1798

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Looking for a task to contribute to boost
by vivek pandya 17 Oct '17

17 Oct '17

Hello Boost Developers, I am Vivek. I contribute small patches to LLVM project. I wanted to work for boost open source project to enhance my C++ knowledge. Could someone suggest some project to me? I will be able to complete task suitable for Google Summer of Code with help and guidance form community. Please also suggest required assignments as I am not a frequent user of Boost libraries. Thanks, Vivek

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Recommend dropping test coverage on msvc-7.1 and msvc-8.0
by James E. King, III 16 Oct '17

16 Oct '17

MSVC 7.1 and MSVC 8.0 are currently listed as "tested" in the Boost 1.65.1 release notes however there are a lot of projects that do not seem to support them well, if at all: http://www.boost.org/development/tests/master/developer/issues.html <http://www.boost.org/development/tests/develop/developer/issues.html> It looks like a large number of libraries will no longer build properly against them based on this report. I'm not sure what the procedure is to come to an agreement to drop a compiler in a release, but it looks like we should consider dropping msvc-7.1 and msvc-8.0. These are very old compilers for Windows development. Dropping them would also allow folks to more easily focus on failures in this report to make sure a release is as clean as possible and simplify the test matrix a little bit. Appveyor only supports back to Visual Studio 2010 at this point, so our ability to get pre-commit checks on compilers before msvc-10.0 is solely based on maintainer effort. I suspect this effort is no longer justified based on the age of the compilers. Thanks - Jim

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Bjam broken on windows with VS2017?
by degski 16 Oct '17

16 Oct '17

My lappie has vs2017 installed, latest (15.4) version, from some days ago. I did the following: 1. Put a clean copy of the boost 1.65.1 source in c: root. 2. issue 'bootstrap.bat' in c:\boost_1_65_1\ (ordinary prompt, no vs thingy). This creates a project-config.jam msvc file. 3. Copied (overwrote project-config.jam) the below contents as project-config.jam to c:\boost_1_65_1\ =======start======= import option ; using clang : 6.0 : "C:\\Program Files\\LLVM\\bin\\clang++.exe" : <compileflags>-fmsc-version=1911 <compileflags>-DBOOST_USE_WINAPI_VERSION=0x1000 <compileflags>-DBOOST_USE_WINDOWS_H=1 <compileflags>-D_WIN32_WINNT=0x1000 <compileflags>-DNOMINMAX <ranlib>"C:\\Program Files\\LLVM\\bin\\llvm-ranlib.exe" <archiver>"C:\\Program Files\\LLVM\\bin\\llvm-ar.exe" <linkflags>-fuse-ld=lld <linkflags>-flto=thin ; option.set keep-going : false ; =======end======== 4. issue 'bjam -d0 --clean' The script of that, and the result is below: Microsoft Windows [Version 10.0.15063] (c) 2017 Microsoft Corporation. All rights reserved. C:\Users\User>cd \ C:\>cd boost_1_65_1 C:\boost_1_65_1>bootstrap.bat Building Boost.Build engine Bootstrapping is done. To build, run: .\b2 To adjust configuration, edit 'project-config.jam'. Further information: - Command line help: .\b2 --help - Getting started guide: http://boost.org/more/getting_started/windows.html - Boost.Build documentation: http://www.boost.org/build/doc/html/index.html C:\boost_1_65_1>bjam -d0 --clean 'C:/Program' is not recognized as an internal or external command, operable program or batch file. etc.. etc... the rest is history? Any ideas? degski

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'Fibre safe optimisations' with gcc/clang (non Windows target) and Boost.Context
by james 15 Oct '17

15 Oct '17

I was considering whether I could/should build an actor system on Rust rather than C++, since it would be an interesting exercise for me. And then I found this article: https://www.reddit.com/r/rust/comments/56wgzq/status_of_coroutines/ In particular: > we noticed that the Rust stdlib is actually using TLS (!) to implement exceptions It seems to me that in practice other compilers might use some sort of thread-local hook for exceptions, whether it is TLS or something lower-level that supports TLS. And that the issue is whether the compiler will assume that the address of the TLS (or thread information block etc) is volatile, or can be cached in a stack frame or register across calls. It seems to me that any such caching of an address might cause difficulty, not just in Rust but also other languages. Microsoft's compiler explicitly has a switch for 'fibre safe optimisations' that disables such caching. The worry I have is code like this: void foo() { try { A() } catch (...) {} B(); // Can switch the context to another underlying OS thread try { C() } catch (...) {} } I am concerned that information about exception handling that was acquired for the first try block, might be retained in the frame and reused in the second try block. and the information might be captured in the frame and/or registers that get saved in the context, but in an arbitrary way. I suspect that access to explicit ABI TLS or C++ thread local is also impacted, although it might be easier to avoid. I guess its not a complete show-stopper if we ensure that fibres never migrate between OS threads, but that is somewhat inconvenient. So - is this actually a Rustc specific issue?

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