October 2014 - Boost - lists.preview.boost.org

[context] msvc /SAFESEH
by Jeff Flinn 12 Aug '15

12 Aug '15

I need to build my application with /SAFESEH which uses boost coroutine which uses context. I'm getting the following link errors: 1>libboost_context-vc100-mt-gd-1_53.lib(jump_i386_ms_pe_masm.obj) : error LNK2026: module unsafe for SAFESEH image. 1>libboost_context-vc100-mt-gd-1_53.lib(make_i386_ms_pe_masm.obj) : error LNK2026: module unsafe for SAFESEH image. I've built boost static libs with the same MSVC vesion and options (sans /SAFESEH as it's not a compile/lib option) Compiler/linker versions: Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.40219.01 for 80x86 Microsoft (R) Incremental Linker Version 10.00.40219.01 Has anyone run into this and resolved the error? Any insight is appreciated. Thanks, Jeff

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[build] b2 headers broken?
by Eric Niebler 02 Mar '15

02 Mar '15

I just updated to the latest develop. I ran bootstrap, then nuked my boost directory and reran b2 headers. Worked fine. Then I changed directory to libs/proto/test and ran ../../../b2 mem_ptr to run a test. Here's what I get: f:\modular-boost\libs\proto\test>..\..\..\b2 mem_ptr Performing configuration checks - symlinks supported : no - junctions supported : yes - hardlinks supported : yes ...patience... ...patience... ...found 4951 targets... ...updating 441 targets... common.mkdir ..\..\..\bin.v2\libs common.mkdir ..\..\..\bin.v2\libs\proto common.mkdir ..\..\..\bin.v2\libs\proto\test common.mkdir ..\..\..\bin.v2\libs\proto\test\mem_ptr.test common.mkdir ..\..\..\bin.v2\libs\proto\test\mem_ptr.test\msvc-12.0 common.mkdir ..\..\..\bin.v2\libs\proto\test\mem_ptr.test\msvc-12.0\debug common.mkdir ..\..\..\bin.v2\libs\proto\test\mem_ptr.test\msvc-12.0\debug\link-static common.mkdir ..\..\..\bin.v2\libs\proto\test\mem_ptr.test\msvc-12.0\debug\link-static\threading-multi link.rm ..\..\..\boost\mpl common.mkdir ..\..\..\boost\mpl link.hardlink ..\..\..\boost\mpl\print.hpp Hardlink created for ..\..\..\boost\mpl\print.hpp <<===>> ..\..\mpl\include\boost\mpl\print.hpp <snip> link.rm ..\..\..\boost\numeric\conversion link.hardlink ..\..\..\boost\numeric\conversion\conversion_traits.hpp The system cannot find the path specified. if exist "..\..\..\boost\numeric\conversion\conversion_traits.hpp" del "..\..\..\boost\numeric\conversion\conversion _traits.hpp" mklink /H "..\..\..\boost\numeric\conversion\conversion_traits.hpp" "..\..\numeric\conversion\include\boost\numeric\ conversion\conversion_traits.hpp" ...failed link.hardlink ..\..\..\boost\numeric\conversion\conversion_traits.hpp... link.hardlink ..\..\..\boost\numeric\conversion\int_float_mixture_enum.hpp The system cannot find the path specified. For some reason, b2 thinks it needs to rerun b2 headers, but it does a crap job of it and dies. What's going on? Eric

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Interactive metaprogramming shells
by Abel Sinkovics 28 Dec '14

28 Dec '14

Hi, I've built interactive shells for preprocessor and template metaprogramming. I've been using them for development and debugging of metaprograms and I think Boost developers could also find them useful. You can type in (metaprogramming) expressions which get evaluated and the result is displayed immediately. For example you can type boost::mpl::push_front<boost::mpl::vector<int, char>, double>::type and you get boost_::mpl::vector<double, int, char> as the result (the boost_ namespace is used because there are some tricks there to make the output more readable). As an example for the preprocessor shell you can type BOOST_PP_REPEAT(3, foo BOOST_PP_TUPLE_EAT(3), ~) and you get foo foo foo as the result. The tools are based on the Boost.Wave library and Clang. You can get them here: Preshell for preprocessor: https://github.com/sabel83/preshell Metashell for template metaprograms: https://github.com/sabel83/metashell You can also try them from your browser here: http://abel.web.elte.hu/shell Feedback is welcome. Regards, Ábel

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[coroutine] x86 msvc11 stack corruption
by Tobias Loew 12 Dec '14

12 Dec '14

Hi, I use Boost 1.55 uni-directional coroutines to build an x86 MSVC11 application. I have a simple pull-type (boost::coroutines::coroutine<void>::pull_type) that under certain reproducable conditions destroys the stack after returning from the coroutine. Here is the corrupted stack as shown by VS2012 > ebs2000.exe!CScriptMainFrame::DoRun(CPascalEditorDoc * 0x00000000, int 0x00000000, int 0x00000000) Line 3372 C++ ebs2000.exe!CScriptMainFrame::OnDebugStepover() Line 4916 C++ mfc110u.dll!_AfxDispatchCmdMsg(CCmdTarget *, unsigned int, int, void (void) *, void *, unsigned int, AFX_CMDHANDLERINFO *) C++ 00000002() Unknown [Frames below may be incorrect and/or missing] mfc110u.dll!CCmdTarget::OnCmdMsg(unsigned int, int 0x00000000, void *, AFX_CMDHANDLERINFO *) Line 364 C++ mfc110u.dll!CWnd::OnCommand(unsigned int 0x00018263, long 0x00000000) Line 2785 C++ mfc110u.dll!CFrameWnd::OnCommand(unsigned int 0x00018263, long 0x00000000) Line 389 C++ ... This only happens in windows x86 32-bit release-builds when the coroutine finishes upon a user-action that also includes a windows WM_SETFOCUS message on my menu-bar. If at least one of the following is true, the stack-corruption does NOT happen: - debug-build - x64 build - using a different pull-type, e.g. enum status_enum{...}; boost::coroutines::coroutine<status_enum>::pull_type - not returning form the coroutine, but pushing just before the end of the coroutine and swapping the pull-type-variable with a default constructed "not-a-coroutine" Even though I have a lot of workarounds, I still would like to know, why this happens. regards Tobias PS: I had to recompile ml /safeseh /c make_i386_ms_pe_masm.asm ml /safeseh /c jump_i386_ms_pe_masm.asm to get SAFESEH-libraries. -- View this message in context: http://boost.2283326.n4.nabble.com/coroutine-x86-msvc11-stack-corruption-tp… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Review request for Compute
by Antony Polukhin 10 Dec '14

10 Dec '14

Hi, Please add the the Compute library to the review schedule. Compute is a GPU/parallel-computing library for C++ based on OpenCL. Author: Kyle Lutz Source code: https://github.com/kylelutz/compute Documentation: http://kylelutz.github.io/compute/ Review Manager: Antony Polukhin Approximate review date: end of November - December 2014 -- Best regards, Antony Polukhin

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Boost People section largely outdated
by Joaquin M Lopez Munoz 09 Dec '14

09 Dec '14

Hi, It is a pity that the Boost People section: http://www.boost.org/users/people.html is so outdated: many people there are no longer around, and, more importantly, many (most) current contributors are not listed. This is is a reminder for people to get themselves on that page! Instructions at http://www.boost.org/development/submissions.html#People Best Joaquín M López Muñoz Telefónica

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[mpl] [build] [testing] Merge pull requests
by Andrey Semashev 08 Dec '14

08 Dec '14

Hi, There were a lot of discussions about MPL recently, and I created a few pull requests to address issues: https://github.com/boostorg/boost/pull/39 Invoke 'headers' target before building testing tools. Note that several testers are currently failing to run because of this problem. Since this affects the testing process, I'd appreciate if someone familiar with it could take a look. https://github.com/boostorg/boost/pull/38 Add MPL.Core tests to the test report. These tests are currently not run by testers. https://github.com/boostorg/mpl/pull/12 Move a misplaced header from MPL to MPL.Core to resolve circular dependency between the two. I believe the first PR is especially critical. Could someone with permissions merge these? Thanks.

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[Range] New I/O functions for ranges
by Indiana 25 Nov '14

25 Nov '14

I'm currently putting together a proposal to the standards committee about a set of range I/O functions, but i think they would make a good addition to Boost as well. They would probably fit in the Range library - i don't think they warrant a library all of their own. The stuff i wrote for the standards proposal is available at http://cpp.indi.frih.net/rangeio/ - it goes into quite a bit of detail about the interface, and links to a sample implementation. But here's the executive summary: There is a single output function - currently called "write_all" - that takes a range and, optionally, a delimiter, like this: // BEGIN CODE ///////////////////////// auto const r = std::array<int, 4>{1, 2, 3, 4}; cout << write_all(r); // prints "1234" cout << "{ " << write_all(r, ", ") << " }"; // prints "{ 1, 2, 3, 4 }" // END CODE /////////////////////////// It takes anything that works with range-for, so it works with range adaptors: // BEGIN CODE ///////////////////////// struct is_even { auto operator()(int x) const -> bool { return x % 2 == 0; } }; cout << write_all(r | reversed | filtered(is_even{})); // prints "42" // END CODE /////////////////////////// Note also that the delimiter doesn't have to be a string (there are some examples in the reference of that). Why not just use std::copy() and stream iterators? Several reasons - the most obvious of which you can see above: this syntax is much cleaner, much less error-prone, well-integrated with the existing stream I/O mechanisms, and it produces properly delimited output (unlike the delimited version of ostream_iterator). But also, stream formatting is properly handled: // BEGIN CODE ///////////////////////// auto const r = std::array<int, 3>{1, 2, 3}; std::cout.width(3); std::cout.fill('0'); // --------------------------- // The old way: using std::begin; using std::end; std::copy(begin(r), end(r), std::ostream_iterator<int>{std::cout, ", "}); // even with Boost.Range, this just reduces to: //boost::copy(r, std::ostream_iterator<int>{std::cout, ", "}); // prints: "001, 2, 3, " // --------------------------- // The new way: std::cout << write_all(r, ", "); // prints "001, 002, 003" // END CODE /////////////////////////// And of course this works as expected in chained expressions: // BEGIN CODE ///////////////////////// auto const r = array<int, 3>{1, 2, 3}; cout.width(3); cout.fill('0'); cout << '(' << setw(3) << setfill('0') << write_all(r, ',') << ')'; // prints: "(001,002,003)" // END CODE /////////////////////////// It is also possible to get more information about errors, and react better to them. If there is an error in the formatting or in the stream during an output operation using std::copy() and ostream_iterator, the algorithm will chug merrily along until it's all the way through the range even though it's no longer writing anything. You will have no way to detect where the problem occurred - did it fail after the first element was written, or *before*, or did it fail after the millionth element? If the range is begin lazy-generated, that could be particularly wasteful, or even problematic. By contrast, write_all() stops immediately when there is an error in the output stream. It is even possible get more information about the last range write operation by capturing the temporary object, like this: // BEGIN CODE ///////////////////////// auto const r = array<int, 3>{1, 2, 3}; auto p = write_all(r); cout << p; if (!cout) { cerr << "only " << p.count << " elements written\n"; cerr << "next element would have been " << *p.next << '\n'; } // END CODE /////////////////////////// On the input side, there are 7 functions: * overwrite * back_insert * front_insert * insert * back_insert_n * front_insert_n * insert_n Overwrite simply replaces the contents of a range with whatever is read from input: // BEGIN CODE ///////////////////////// auto r = array<int, 100>{}; cin >> overwrite(r); // reads up to 100 ints // END CODE /////////////////////////// The *insert functions map to the *insert_iterators in the standard library, using push_back(), push_front(), or insert(). In each case: in >> ???insert(r[, i]); is basically equivalent to: copy(istream_iterator<value_type_of_r>{in}, // use braces on the next line, or face the most vexing parse istream_iterator<value_type_of_r>{}, ???inserter(r[, i])); The *insert_n functions are for the common case where you know in advance how many elements will be read, at maximum - or for when you want to limit the amount of elements read in a single read operation. This: in >> ???insert_n(r[, i], n); is conceptually equivalent to: copy_n(istream_iterator<value_type_of_r>{in}, n, ???inserter(r[, i])); except it can handle formatting and errors properly. The reference at http://cpp.indi.frih.net/rangeio/ goes into much more detail, of course. Why add it to Boost? Because these operations (reading/writing ranges) are so common they are almost universal, and there is no standard facility that handles them easily or well. They are not *difficult* to implement, but they are far from trivial - for example, you might think write_all() is just a simple range-for loop or for_each(), and it is... up until you add error checking, the delimiter, and formatting awareness. A sample implementation already exists - it can be implemented portably in pure standard C++11. (Can it be implemented in C++03 with? Good question. It might be possible with some Boost help, but it might require dependencies on libraries other than Boost.Range. If this proposal finds approval, that's something i can look into.) Would there be any interest in adding these functions to Boost.Range?

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[dynamic_bitset] capacity(), reserve(), shrink_to_fit()
by Riccardo Marcangelo 24 Nov '14

24 Nov '14

Hi, I have implemented capacity(), reserve(), and shrink_to_fit() for dynamic_bitset. I find these useful and am surprised by their omission. I'm wondering if there is any interest in including them in Boost. Perhaps there are reasons why they're not implemented? Riccardo -- View this message in context: http://boost.2283326.n4.nabble.com/dynamic-bitset-capacity-reserve-shrink-t… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Changes in Boost.Optional
by Dean Michael Berris 24 Nov '14

24 Nov '14

Suppose I have the following type: struct container { boost::optional<uint16_t> optional() const { return value_; } private: boost::optional<uint16_t> value_; }; struct value_wrapper { value_wrapper(const container& c) : c_(c) {} operator uint16_t () { return 1; } operator boost::optional<uint16_t>() { return c_.optional(); } private: const container& c_; }; And that I have the following function: value_wrapper value(const container& c) { return value_wrapper(c); } The following used to work in MSVC 2010: container c; // leave c.value_ alone. boost::optional<uint16_t> some_value = value(c); assert(!some_value); Now with Boost 1.56, this breaks because the constructor for some_value from a temporary optional is now marked explicit. What is the work-around for the previous behavior to be regained? All the following changes cause the assertion to fail: boost::optional<uint16_t> some_value(value(c)); assert(!some_value); // some_value's constructor will use the uint16_t conversion operator, therefore some_value == 1 boost::optional<uint16_t> some_value = static_cast<boost::optional<uint16_t> >(value(c)); assert(!some_value); // same problem as above, the temporary created will favor the uint16_t conversion operator Help? PS. For better context, see https://github.com/cpp-netlib/cpp-netlib/blob/0.11-devel/boost/network/prot…

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