Hello, A typical "hello world" C++ fails in an environment with both `gcc-toolchain' and `clang-toolchain', apperently due to the setup of the `CPLUS_INCLUDE_PATH' environment variable (used because of the `#include <iostream>' instruction), when compiling with `clang++'.
I do not know if this is a bug or the expected behaviour. Obviously one is not likely to explicitly load an environment with both `gcc-toolchain' and `clang-toolchain' but migth do so implictly (and possibly not being aware of it) for instance having `gcc-toolchain' globally installed and at some point loading `clang-toolchain' in an environment. Note that it is not critical at all in practice in my case, and I do not know whether it it is desirable to fix it in some way, or, maybe mention the incompatibility somewhere (<https://guix.gnu.org/manual/en/html_node/Development.html> ?) if not already done so – in which case I am sorry for the noise. Please find below: 1. a simplified C++ "hello world" hello.cpp program 2. an expected g++ behaviour in a `gcc-toolchain' environment 3. an expected clang++ behaviour in a `clang-toolchain' environment 4. an environment with both `gcc-toolchain' & `clang-toolchain' - 4.1. with an expected behaviour using `g++' - 4.2. with an (expected or not?) error using `clang++' - 4.3. a (non desirable) fix of the `CPLUS_INCLUDE_PATH' (removing `/gnu/store/…/include/c++') 5. the employed channels if it may help Thanks much for the continous development and support, and once again sorry for the possible noise if this is a known expected behaviour. With best regards, Emmanuel 1 simplified (no newline) C++ "hello world" hello.cpp program ═════════════════════════════════════════════════════════════ ┌──── │ #include <iostream> │ │ int main() { │ std::cout << "Hello World!"; │ return 0; │ } └──── 2 `gcc-toolchain' environment ═════════════════════════════ ┌──── │ guix environment -C --ad-hoc gcc-toolchain coreutils grep │ env | grep CPLUS_INCLUDE_PATH │ g++ hello.cpp │ ./a.out └──── ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ CPLUS_INCLUDE_PATH=/gnu/store/gsylxn8q06w6y7622nw159f3q1vvcx2i-profile/include/c++:/gnu/store/gsylxn8q06w6y7622nw159f3q1vvcx2i-profile/include Hello World! ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 3 `clang-toolchain' environment ═══════════════════════════════ ┌──── │ guix environment -C --ad-hoc clang-toolchain coreutils grep │ env | grep CPLUS_INCLUDE_PATH │ clang++ hello.cpp │ ./a.out └──── ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ CPLUS_INCLUDE_PATH=/gnu/store/8qlafmilvc0g1yv8lmilpjmps3p4nrmq-profile/include Hello World! ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 4 environment with both `gcc-toolchain' & `clang-toolchain' ═══════════════════════════════════════════════════════════ 4.1 compilation with `g++' ────────────────────────── `g++' in an environment with both gcc and clang toolchains is fine: ┌──── │ guix environment -C --ad-hoc gcc-toolchain clang-toolchain coreutils grep │ env | grep CPLUS_INCLUDE_PATH │ g++ hello.cpp │ ./a.out └──── ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ CPLUS_INCLUDE_PATH=/gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++:/gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include Hello World! ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 4.2 compilation with `clang++' (FAIL) ───────────────────────────────────── But `clang++' in the same environment (with both gcc and clang toolchains) breaks, raising the following error: ┌──── │ guix environment -C --ad-hoc gcc-toolchain clang-toolchain coreutils grep │ clang++ hello.cpp └──── Error obtained during the `clang++ hello.cpp' step: ┌──── │ In file included from hello.cpp:1: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/iostream:39: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/ostream:38: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/ios:39: │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/exception:105:3: error: unknown type name '_GLIBCXX17_DEPRECATED' │ _GLIBCXX17_DEPRECATED │ ^ │ In file included from hello.cpp:1: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/iostream:39: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/ostream:38: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/ios:39: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/exception:147: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/bits/exception_ptr.h:40: │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/new:126:1: error: unknown type name '_GLIBCXX_NODISCARD' │ _GLIBCXX_NODISCARD void* operator new(std::size_t) _GLIBCXX_THROW (std::bad_alloc) │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/new:128:1: error: unknown type name '_GLIBCXX_NODISCARD' │ _GLIBCXX_NODISCARD void* operator new[](std::size_t) _GLIBCXX_THROW (std::bad_alloc) │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/new:140:1: error: unknown type name '_GLIBCXX_NODISCARD' │ _GLIBCXX_NODISCARD void* operator new(std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/new:142:1: error: unknown type name '_GLIBCXX_NODISCARD' │ _GLIBCXX_NODISCARD void* operator new[](std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/new:174:1: error: unknown type name '_GLIBCXX_NODISCARD' │ _GLIBCXX_NODISCARD inline void* operator new(std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/new:175:10: error: cannot initialize return object of type 'int *' with an lvalue of type 'void *' │ { return __p; } │ ^~~ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/new:176:1: error: unknown type name '_GLIBCXX_NODISCARD' │ _GLIBCXX_NODISCARD inline void* operator new[](std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/new:177:10: error: cannot initialize return object of type 'int *' with an lvalue of type 'void *' │ { return __p; } │ ^~~ │ In file included from hello.cpp:1: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/iostream:39: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/ostream:38: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/ios:39: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/exception:148: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/bits/nested_exception.h:40: │ In file included from /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/bits/move.h:57: │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:696:27: error: expected unqualified-id │ _GLIBCXX20_DEPRECATED("use is_standard_layout && is_trivial instead") │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:696:27: error: expected ')' │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:696:26: note: to match this '(' │ _GLIBCXX20_DEPRECATED("use is_standard_layout && is_trivial instead") │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:2648:5: error: unknown type name '_GLIBCXX20_CONSTEXPR' │ _GLIBCXX20_CONSTEXPR │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:2650:5: error: no variable template matches partial specialization │ _Require<__not_<__is_tuple_like<_Tp>>, │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:2652:31: error: expected ';' at end of declaration │ is_move_assignable<_Tp>> │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:2653:10: error: unknown type name '_Tp' │ swap(_Tp&, _Tp&) │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:2653:16: error: unknown type name '_Tp' │ swap(_Tp&, _Tp&) │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:2654:51: error: use of undeclared identifier '_Tp' │ noexcept(__and_<is_nothrow_move_constructible<_Tp>, │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:2654:55: error: expected a type │ noexcept(__and_<is_nothrow_move_constructible<_Tp>, │ ^ │ /gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include/c++/type_traits:2653:5: error: C++ requires a type specifier for all declarations │ swap(_Tp&, _Tp&) │ ^ │ fatal error: too many errors emitted, stopping now [-ferror-limit=] │ 20 errors generated. └──── 4.3 (non desirable) fix of the `CPLUS_INCLUDE_PATH' (removing `/gnu/store/.../include/c++') ─────────────────────────────────────────────────────────────────────────────────────────── For information, it is possible (but obviously in general not desirable) to fix the `CPLUS_INCLUDE_PATH' variable (removing `/gnu/store/.../include/c++'), which leads to a correct compilation (and execution). ┌──── │ guix environment -C --ad-hoc gcc-toolchain clang-toolchain coreutils grep │ export CPLUS_INCLUDE_PATH=/gnu/store/3ka3a9wgx5sk6ac84nldx7ldpxppn29z-profile/include │ clang++ hello.cpp │ ./a.out └──── ┌──── │ Hello World! └──── 5 channels ══════════ ┌──── │ guix describe --format=channels └──── ┌──── │ (list (channel │ (name 'guix-hpc) │ (url "https://gitlab.inria.fr/guix-hpc/guix-hpc.git";) │ (commit │ "fa87605fe93fb85b02dad9db246299bcf223f2e0")) │ (channel │ (name 'guix-hpc-non-free) │ (url "https://gitlab.inria.fr/guix-hpc/guix-hpc-non-free.git";) │ (commit │ "43d8cb72144a183aa7a93499f9c59ec0f84244b0")) │ (channel │ (name 'guix) │ (url "https://git.savannah.gnu.org/git/guix.git";) │ (commit │ "c6872990b51971922f3064cba54ab752fcdc1559") │ (introduction │ (make-channel-introduction │ "9edb3f66fd807b096b48283debdcddccfea34bad" │ (openpgp-fingerprint │ "BBB0 2DDF 2CEA F6A8 0D1D E643 A2A0 6DF2 A33A 54FA"))))) └────
