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Boost.Outcome review - First questions
by Vicente J. Botet Escriba 21 May '17

21 May '17

Hi, I've tried to read the tutorial, but it is too long for my taste. I will try it later on :( A minor issue * "As inferred in the example code cases earlier, you can check if an |expected<T, E>| has an expected value via a simple test for boolean true or more explicitly via |.has_value()| before retrieving the value using |.value()|." This is not correct. It is correct for the de-reference operator, but .value() don't needs any check with .has_value(). Instead of some deviation, I would expect a report of all deviations and a rationale explaining why it is better to do this way. # "Types |T| and |E| cannot be constructible into one another. This is a fundamental design choice in basic_monad to significantly reduce compile times so it won't be fixed." * "Note though that |expected<void, void>| is permitted (which is legal in the LEWG proposal)." What are the compile time cost |associated the std::experimental::expected<T,E>? | I don't see what |expected<void, void> could mean. | # |unexpected_type<E>| is implemented as an |expected<void, E>| and it lets the basic_monad machinery do the implicit conversion to some |expected<T, E>| through the less representative to more representative conversion rules. Note that our Expected passes the LEWG Expected test suite just fine, so you probably won't notice this implementation detail in your code. The test of my POC implementation couldn't be complete, so this is not a sign of compatibility. Which operation allow to convert expected<void,E> to expected<T,E> and what is the expected behavior if expected<void,E> has a value? # Our |expected<T, E>| defaults E to |std::error_code| rather than |std::error_condition| (the LEWG proposal fixes this in P0323R2). I don't have a strong opinion on which default would be the best. As you suggested, I have added it to the next revision. We don't implement the ordering and hashing operator overloads due to https://akrzemi1.wordpress.com/2014/12/02/a-gotcha-with-optional/. The fact the LEWG proposal does as currently proposed is a defect (it will be discussed by LEWG with P0323R2 in Toronto). As for optional this could be considered a defect. The question is if we want expected to differen from the optional interface. If we considered it a defect, I don't believe that we should remove comparison, but IMHO we should make the constructor from T explicit. I don't expect the committee to fix this for expected and let the issue for optional. We will see. # We don't implement |make_expected_from_call()| as we think it highly likely to be removed from the next version of the proposal due to it conferring little value. This is possible and the function can be implemented very easily. I can live with and without it. # Our |make_expected()| and |make_unexpected()| functions deviate significantly as we believe the LEWG ones to be defective in various ways. This topic will be discussed in Toronto and reconciliation later is highly likely. Please, could you tell how those are defective so that we can fix them? Otherwise I don't see what we could discuss in Toronto. # Our |value_or()| member functions pass through the reference rather than returning by value (we don't understand why the LEWG proposal does except that |std::optional<T>| does, which itself is a bad design choice and it should be changed). Well, what is the advantage to returning by reference? Rather than |void|, our |value_type| and |error_type| typedefs are set to a descriptive compiler error generating type if the Expected is configured with |void|. If you want to know if no type was configured, use the static constexpr bools at |expected<T, E>::has_value_type| and |expected<T, E>::has_error_type| or use |raw_value_type| and |raw_error_type|. The reason for this deviation is to make metaprogramming using Outcome's transports much easier and less error prone. Sorry. I don't understand what is the issue. Could you elaborate? # Our Expected always defines the default, copy and move constructors even if the the type configured is not capable of it. That means |std::is_copy_constructible| etc returns true when they should return false. The reason why is again to significantly improve compile times by hugely reducing the number of templates which need to be instantiated during routine basic_monad usage, and again this won't be fixed. Instead use the static constexpr bools at: Defining these operation when they can not be implemented means that you cannot use SFINAE on this type. Maybe I'm wrong, but I believe we want to check if a type is constructible, ... using the C++ standard type traits. Next follow the first questions I have mainly from the reference documentation of expected<T,E>. In general I find most of the operation not specified enough. I would like to have something in line with the standard way of specifying an interface. * it is not clear from the reference documentation if expected<void,E> is valid? |* |is expected<T,E> the sum type of T, E and empty? and exception_ptr? |"outcome<T>| can be empty, or hold an instance of a type |T|, or hold an instance of |error_code_extended|, or hold an instance of |std::exception_ptr|. This saves you having to wrap an error code into an exception pointer instance, thus also avoiding a memory allocation." std::experimental::expected requires that its Error type to be no throw constructible, copyable and movable. What are the exception warranties for |error_code_extended? | What are the exception warranties for |outcome<T>||? | * inplace construction What is the difference between: constexpr expected (value_t _) noexcept(std::is_nothrow_default_constructible< value_type >::value) Implicit constructor of a valued monad (default constructed) and constexpr expected (in_place_t, Args &&... args) noexcept(std::is_nothrow_constructible< value_type, Arg, Args... >::value) when there is no Args. IMO the second subsumes the first and so there is no need fro the first overload and the value_t tag. * default constructor constexpr expected () noexcept(is_nothrow_default_constructible) Default constructor. This doesn't say what the default constructor does. * Shouldn't constexpr expected (in_place_t, std::initializer_list l) noexcept(std::is_nothrow_constructible< value_type, std::initializer_list>::value) Implicit constructor from an initializer list. be constexpr explicit expected(in_place_t, initializer_list il, Args&&... args); * What is void_rebound and where it is defined constexpr expected (const void_rebound &v) noexcept(std::is_nothrow_copy_constructible< error_type >::value) Implicit constructor from an identically configured basic_monad<void> by copy. * construction from error type What is wrong with template <class... Args> constexpr explicit expected(unexpect_t, Args&&...); template <class U, class... Args> constexpr explicit expected(unexpect_t, initializer_list, Args&&...); Why do you prefer an implicit conversion. This deviation must be in the rationale of the differences. constexpr expected (const error_type &v) noexcept(std::is_nothrow_copy_constructible< error_type >::value) Implicit constructor from a error_type by copy. constexpr expected (error_type &&v) noexcept(std::is_nothrow_move_constructible< error_type >::value) * raw types It is not clear what is the difference between xxx and raw_xxx typedef value_storage_type::value_type value_type The type potentially held by the monad. typedef implementation_policy::value_type raw_value_type The raw type potentially held by the monad. typedef value_storage_type::error_type error_type The error code potentially held by the monad. typedef implementation_policy::error_type raw_error_type The raw error code potentially held by the monad. typedef value_storage_type::exception_type exception_type The exception ptr potentially held by the monad. typedef implementation_policy::exception_type raw_exception_type The raw exception ptr potentially held by the monad. * What is the "The exception ptr potentially held by the monad"? * what is the sizeof expected <T,E>? * is basic_monad something proposed or an implementation detail? If the first, this should be renamed, if the second this class should not appear in the documentation and the word monad should be banned. * What is expected<Policy> in template<class Policy , typename = typename std::enable_if<std::is_same<typename implementation_policy::value_type, typename Policy::value_type>::value || std::is_void<typename Policy::value_type>::value || std::is_constructible<typename implementation_policy::value_type, typename Policy::value_type>::value>::type, typename = typename std::enable_if<std::is_same<typename implementation_policy::error_type, typename Policy::error_type>::value || std::is_constructible<typename implementation_policy::error_type, typename Policy::error_type>::value>::type, typename = typename std::enable_if<std::is_same<typename implementation_policy::exception_type, typename Policy::exception_type>::value || std::is_constructible<typename implementation_policy::exception_type, typename Policy::exception_type>::value>::type> constexpr expected (expected< Policy > &&o, explicit_conversion_from_different_policy=explicit_conversion_from_different_policy()) Explicit move constructor from a basic_monad with a differing implementation policy. For this constructor to be available, value_type, error_type and exception_type must be identical or constructible. * move constructor/copy constructor The reference documentation doesn't says what this does. * Missing move/copy assignment * bool conversion should be explicit * is_ready has nothing to be with expected. * Shouldn't value_or return by value? otherwise what would be the difference between get_or and value_or? * emplace. Missing overload template <class U, class... Args> void emplace(initializer_list, Args&&...); * swap: What is the meaning of swapping an expected with an option? swap must follow the standard signature. * Missing preconditions on the observers, which make them wide operations. Saying that they return an address makes them wide operations however accessing to the contents of this address will be undefined behavior. I prefer the standard way, defining a narrow function and stating clearly the pre-conditions. * what error_or <https://ned14.github.io/boost.outcome/structboost_1_1outcome_1_1v1__xxx_1_1…> returns if it contains an exception? * what is the difference between get_error_or and error_or? https://github.com/ned14/boost.outcome/issues/19 * Missing overload for get_unexpected. In addition it doesn't return an unexpected_type. constexpr const E & get_unexpected () const; Best, Vicente

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Boost.Outcome and the C++ standard proposals
by Vicente J. Botet Escriba 20 May '17

20 May '17

Hi, for those that will follow the Boost.Outcome review I wanted to share some links related to the standard: The draft of the next revision : * D0323R2 -*A proposal to add a utility class to represent expected monad *(Revision 4) - https://github.com/viboes/std-make/blob/master/doc/proposal/expected/d0323r… The monadic interface draft proposal * DXXXX - *C++ Monadic inteface* - https://github.com/viboes/std-make/blob/master/doc/proposal/monads/Monads.md This is based on Hana customization in its pre-Boost version. And last a very draft paper I don't pretend to send to the standard meetings, at least not yet, about how FileSystem TS could be adapted to take in account the proposes status_value and expected classes. * DXXXX -*Refactoring FileSystem TS using **|expected|**or **|status_value|*||- https://github.com/viboes/std-make/blob/master/doc/proposal/expected/DXXXXR… This paper show that there is not silver bullet solution to reporting errors, but that making abstractions as status_value or expected makes the interface more clear, composable and readable (for me at least) than using out parameters error codes. The paper show also that wanting to have exception interfaces and non-exception interface forces to double the interface. Using expected could reduce it at the price of using .value(). I have an POC implementation in https://github.com/viboes/std-make/tree/master/include/experimental/fundame… Look for expected, functor, applicative, monad, monad_error folders for the implementation and std for the customization. My intention is to show that there is something on-going on the standard aside the expected proposal as requested by the committee. Note these drafts are of course not reviewed yet by the committee and I don't know if they will like the direction. We will see in Toronto next July Best, Vicente P.S. The dead line for next meeting is the 19 Jun. Any feedback is welcome, but as this is not C++ standard ML, I will prefer to have this feedback either privately or vi a the std-proposals ML.

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Issue with cross-compiling boost
by Roy Kleefman 17 May '17

17 May '17

Hello all, I am trying to cross-compile the boost libraries for an ARM based linux system. The system is an FX30 IoT gateway by Sierra Wireless. It comes with a dedicated, Eclipse based, development studio, which supplies the cross-compiler & a disk image with all the required headers & libraries to cross-compile to. For starters, I've created a user-config.jam file in my home directory with the following contents (my apologies on this being a bit hard to read, I had to use absolute paths or else the cross-compiler would complain): using gcc : arm : /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-g++ : <cxxflags>--sysroot=/home/developer /legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/armv7a-vfp-neon-poky-linux-gnueabi <include>~/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/armv7a-vfp-neon-poky-linux-gnueabi <linkflags>-L/home/developer /legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/lib -L/home/developer /legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/local/lib <compileflags>-v ; As you can see I've set the sysroot to the directory that is the / directory of the disk image. I've also set library paths to the disk image's /usr/lib & /usr/local/lib directories. I also tried several variations on setting the include path to point to the disk image, but I run into issues when compiling the boost libraries. When the compiler hits the alloc_lib.c file, it errors out on: COLLECT_GCC=/home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-g++ Target: arm-poky-linux-gnueabi Configured with: /work/build_src/tmp/work-shared/gcc-4.9.1-r0/gcc-4.9.1/configure --build=x86_64-linux --host=x86_64-pokysdk-linux --target=arm-poky-linux-gnueabi --prefix=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr --exec_prefix=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr --bindir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi --sbindir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi --libexecdir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi --datadir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/share --sysconfdir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/etc --sharedstatedir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/com --localstatedir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/var --libdir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/lib/arm-poky-linux-gnueabi --includedir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/include --oldincludedir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/include --infodir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/share/info --mandir=/opt/swi/y17-ext/sysroots/x86_64-pokysdk-linux/usr/share/man --disable-silent-rules --disable-dependency-tracking --with-libtool-sysroot=/work/build_src/tmp/sysroots/x86_64-nativesdk-pokysdk-linux --with-gnu-ld --enable-shared --enable-languages=c,c++ --enable-threads=posix --enable-multilib --enable-c99 --enable-long-long --enable-symvers=gnu --enable-libstdcxx-pch --program-prefix=arm-poky-linux-gnueabi- --without-local-prefix --enable-target-optspace --enable-lto --enable-libssp --disable-bootstrap --disable-libmudflap --with-system-zlib --with-linker-hash-style=gnu --enable-linker-build-id --with-ppl=no --with-cloog=no --enable-checking=release --enable-cheaders=c_global --with-gxx-include-dir=/opt/swi/y17-ext/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/include/c++/4.9.1 --with-build-time-tools=/work/build_src/tmp/sysroots/x86_64-linux/usr/arm-poky-linux-gnueabi/bin --with-sysroot=/opt/swi/y17-ext/sysroots/armv7a-vfp-neon-poky-linux-gnueabi --with-build-sysroot=/work/build_src/tmp/sysroots/swi-mdm9x15 --enable-poison-system-directories --with-mpfr=/work/build_src/tmp/sysroots/x86_64-nativesdk-pokysdk-linux --with-mpc=/work/build_src/tmp/sysroots/x86_64-nativesdk-pokysdk-linux --enable-nls --with-arch=armv7-a Thread model: posix gcc version 4.9.1 (GCC) COLLECT_GCC_OPTIONS='-O3' '-finline-functions' '-Wno-inline' '-Wall' '-v' '-pthread' '-D' 'BOOST_ALL_NO_LIB=1' '-D' 'BOOST_CONTAINER_STATIC_LINK=1' '-D' 'NDEBUG' '-I' '.' '-c' '-o' 'bin.v2/libs/container/build/gcc-arm/release/link-static/threading-multi/alloc_lib.o' '-shared-libgcc' '-march=armv7-a' '-mtls-dialect=gnu' /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/cc1 -quiet -v -I . -iprefix /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/ -D_REENTRANT -D BOOST_ALL_NO_LIB=1 -D BOOST_CONTAINER_STATIC_LINK=1 -D NDEBUG libs/container/src/alloc_lib.c -quiet -dumpbase alloc_lib.c -march=armv7-a -mtls-dialect=gnu -auxbase-strip bin.v2/libs/container/build/gcc-arm/release/link-static/threading-multi/alloc_lib.o -O3 -Wno-inline -Wall -version -finline-functions -o /tmp/ccNP4WY6.s GNU C (GCC) version 4.9.1 (arm-poky-linux-gnueabi) compiled by GNU C version 4.9.1, GMP version 6.0.0, MPFR version 3.1.2, MPC version 1.0.2 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 ignoring nonexistent directory "/home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/../../../../../arm-poky-linux-gnueabi/include" ignoring duplicate directory "/home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/../../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/include" ignoring nonexistent directory "/opt/swi/y17-ext/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/lib/gcc/arm-poky-linux-gnueabi/4.9.1/include" ignoring nonexistent directory "/opt/swi/y17-ext/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/local/include" ignoring duplicate directory "/home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/../../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/include-fixed" ignoring nonexistent directory "/home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/../../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/../../../../../arm-poky-linux-gnueabi/include" ignoring nonexistent directory "/opt/swi/y17-ext/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/include" #include "..." search starts here: #include <...> search starts here: . /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/include /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/include-fixed End of search list. GNU C (GCC) version 4.9.1 (arm-poky-linux-gnueabi) compiled by GNU C version 4.9.1, GMP version 6.0.0, MPFR version 3.1.2, MPC version 1.0.2 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: 89d75e59a6fc83bde96963c802ac00fb In file included from libs/container/src/alloc_lib.c:19:0: libs/container/src/dlmalloc_ext_2_8_6.c:13:100: fatal error: errno.h: No such file or directory #include "errno.h" //dlmalloc bug EINVAL is used in posix_memalign without checking LACKS_ERRNO_H ^ compilation terminated. "/home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-g++" -x c -O3 -finline-functions -Wno-inline -Wall -v -pthread -DBOOST_ALL_NO_LIB=1 -DBOOST_CONTAINER_STATIC_LINK=1 -DNDEBUG -I"." -c -o "bin.v2/libs/container/build/gcc-arm/release/link-static/threading-multi/alloc_lib.o" "libs/container/src/alloc_lib.c" ...failed gcc.compile.c bin.v2/libs/container/build/gcc-arm/release/link-static/threading-multi/alloc_lib.o... ...failed updating 1 target... ...updated 123 targets... Which I find strange, because the "errno.h" header is available on the disk image. It is found in these directories: <sysroot>/usr/include/linux/errno.h <sysroot>/usr/include/bits/errno.h <sysroot>/usr/include/sys/errno.h <sysroot>/usr/include/asm-generic/errno.h <sysroot>/usr/include/asm-generic/errno-base.h <sysroot>/usr/include/errno.h <sysroot>/usr/include/asm/errno.h What struck me as odd is that the include search for this file has a lot shorter search list than for other files. For example, searching for headers for libboost_atomic, it looks in more directories: #include "..." search starts here: #include <...> search starts here: . /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/include /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/include /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/../../lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.9.1/include-fixed /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/include/c++/4.9.1 /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/include/c++/4.9.1/arm-poky-linux-gnueabi /home/developer/legato/packages/legato.toolchain.1.7.3.SWI9X15Y_07112100-wp85-wp750x-native-x86_64-201701091132/resources/native/sysroots/armv7a-vfp-neon-poky-linux-gnueabi/usr/include/c++/4.9.1/backward Can anybody help me with this problem? Kind regards, Roy Kleefman [cid:image001.jpg@01D2CEED.E27ADF00] Rohill * Edisonstraat 12 * 7903 AN Hoogeveen * The Netherlands Phone: +31-528-263355 * Fax: +31-528-271844 * www.rohill.com<http://www.rohill.com/> Chamber of Commerce Meppel registration no. 09084362 This email, including any attached files, is confidential, may be legally privileged, and is solely for the intended recipient(s). If you have received this email in error, please destroy it and notify Rohill immediately. Any unauthorised use, dissemination, disclosure, copying or printing is strictly prohibited. Thank you. [cid:image003.jpg@01D2CEED.E27ADF00]<http://www.criticalcommunicationsworld.com/>

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UTF: test/included/unit_test.hpp vs test/unit_test.hpp
by Manav Bhatia 15 May '17

15 May '17

Hi, I am using the UTF in my code. Below is the key component of my code that I have been using on Mac for a few years with boost installed from macports. #define BOOST_TEST_DYN_LINK #define BOOST_TEST_MODULE MAST_TESTS #include <boost/test/unit_test.hpp> // C++ includes #include <memory> struct GlobalTestFixture { GlobalTestFixture() { /* my code here */ } ~GlobalTestFixture() { } }; BOOST_GLOBAL_FIXTURE( GlobalTestFixture ); A few days ago I started using this code on Ubuntu and kept getting segmentation faults with random values being returned for boost::unit_test::framework::master_test_suite().argc I managed to get rid of this problem by changing the included header to #include <boost/test/included/unit_test.hpp> I have seen the description here: http://www.boost.org/doc/libs/1_48_0/libs/test/doc/html/utf/compilation/dir… <http://www.boost.org/doc/libs/1_48_0/libs/test/doc/html/utf/compilation/dir…>. However, I am not quite able to follow why this problem occurred on Ubuntu (with system boost library) when I was still linking against the precompiled library (version 1.58). Is there a test I can include in my code to automatically switch from one include to the other? I will appreciate some guidance. Regards, Manav

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Test: Skip test from fixture
by Florian Lindner 15 May '17

15 May '17

Hello, given I have a test with a fixture. How can I skip that test from within the fixture? Thanks, Florian

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(no subject)
by Daniel Estermann 14 May '17

14 May '17

Hello everybody, I am trying to build HPX (https://github.com/STEllAR-GROUP/hpx) which uses Boost under Cygwin and I bumped into an incompatibility issue between the class boost::asio::detail::winsock_init_base and the WinSocket-API exposed by Cygwin. The error summary: the types of variable members in winsock_init_base::data are long (defined in boost/asio/detail/winsock_init.hpp). These variable are passed to functions _InterlockedIncrement, _InterlockedExchange etc (called from boost/asio/detail/impl/winsock_init.ipp). But there are no functions defined in Cygwin (in headers in /usr/include/w32api) expecting a long parameter. Here you can see the full gcc output: https://pastebin.com/raw/8MDa8QXJ I also produced the the preprocessor output which I zipped and uploaded to https://www.dropbox.com/s/anmjsjnvq7lnesr/hpx_init.cpp.i.zip?dl=0 Am I overlooking anything or is this really an incompatibility issue?

1 0

Context and coroutine for ARM
by Daniel Estermann 14 May '17

14 May '17

I am trying to cross compile boost 1.63 for Raspberry Pi, i.e. for an ARM core. But the build fails for boost-coroutine and boost-context. Here is my build log http://sprunge.us/NVDd As far as I can see from development files in https://github.com/ boostorg/context/tree/develop/src/asm ARM is supported at least by boost-context. Is there anything I can do about or any progress for this issue? If not, is there an older version I should try? Regards

5 18

Using the (new) C++ standard library in boost::dll
by Benjamin Buch 12 May '17

12 May '17

The boost::dll depends on 4 different boost-libraries which all have counterparts in the C++17 standard library. Worse, two of them (system & filesystem) are not header-only libraries, so you need to link against these libraries. Is it possible and planned to use the standard library counterparts as plug in replacement for these boost dependencies in a future release? In my opinion this would improve the usability massively, especially when you already use this counterparts in the rest of your program. Best regards, Benjamin

3 2

boost::process::search_path() and compound cmd
by niXman 12 May '17

12 May '17

Hi, I need to execute the 'stdbuf -oL -eL python scrypt.py' cmd but if I write the: auto p = boost::process::search_path("stdbuf -oL -eL python2"); boost::process::child c(p, "script.py"); c.wait(); I get the exception with 'execve failed: Permission denied' message. My question is, what should I change in my example for executing the 'stdbuf -oL -eL python2 scrypt.py' cmd? Thanks. -- Regards, niXman ___________________________________________________ Dual-target(32 & 64-bit) MinGW-W64 compilers for 32 and 64-bit Windows: https://sf.net/p/mingw-w64/

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[Fiber] Can a fiber promise be set in a different OS thread on which has no fibers running
by lin li 11 May '17

11 May '17

I have tested the following example code with Boost 1.61. And it worked (ignore the potential race conditions when accessing the variable 'p'). But I am not sure the fiber promise can be used in this way or I am just being lucky. #include <cstdlib> #include "boost/fiber/fiber.hpp" #include "boost/fiber/future.hpp" #include "boost/thread.hpp" #include <set> #include <iostream> #include <boost/date_time/posix_time/posix_time_duration.hpp> #include <boost/thread/pthread/mutex.hpp> #include <boost/thread/lock_guard.hpp> #include "boost/thread/pthread/thread_data.hpp" #include "boost/chrono/duration.hpp" using namespace std; boost::fibers::promise<int>* p; void wait() { p = new boost::fibers::promise<int>; auto future = p->get_future(); auto status = future.wait(); std::cout << "Value: " << future.get() << std::endl; delete p; } void f() { boost::fibers::fiber fiberJob(&wait); fiberJob.join(); } void setf() { // Is it safe to do this? boost::this_thread::sleep(boost::posix_time::seconds(5)); p->set_value(20); } void f1() { boost::fibers::fiber fiberJob(&setf); fiberJob.join(); } int main(int argc, char** argv) { boost::thread t(&f); setf(); cout << "Here" << endl; t.join(); cout << "Here 2" << endl; return 0; }

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