[Bug] Fails to compile with TBB and XSIMD enabled #2736

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1. spectre-ns commented on Oct 31, 2023

   

   spectre-ns

   on Oct 31, 2023

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   Example of failed build

   https://github.com/spectre-ns/xtensor/actions/runs/6706077908/job/18221831529
2. JohanMabille commented on Nov 1, 2023

   

   JohanMabille

   on Nov 1, 2023

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   I guess we need to capture needs_cast here, but I wonder if it's a compiler issue. Do you have the same issue with MSVC 2022 ?
3. spectre-ns commented on Nov 1, 2023

   

   spectre-ns

   on Nov 1, 2023

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   @JohanMabille yes the same issue exists in MSVC 2022
4. spectre-ns commented on Nov 1, 2023

   

   spectre-ns

   on Nov 1, 2023

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   @JohanMabille looks like this is a bug as constexpr variables should be captured in lambda scope implicitly.

   https://stackoverflow.com/questions/33873788/can-i-use-a-constexpr-value-in-a-lambda-without-capturing-it

   Specifically MSVC:

   https://stackoverflow.com/questions/71493298/why-cant-a-constexpr-variable-be-seen-only-by-a-capturing-lambda
5. spectre-ns commented on Nov 1, 2023

   

   spectre-ns

   on Nov 1, 2023

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   Also there are issues out of the box around tbb defining min and max that need to be mitigated using #define NOMINMAX
6. tdegeus

   added

   Compiler bug

   C++20

   on Nov 9, 2023
7. spectre-ns commented on Nov 12, 2023

   

   spectre-ns

   on Nov 12, 2023

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   @tdegeus this issue isn't C++20 specific. Not sure what that label means though.
8. PerretB commented on Jul 19, 2024

   

   PerretB

   on Jul 19, 2024

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   @spectre-ns @JohanMabille hello, did you find a workaround for this problem? Activating the flag /Zc:lambda does solve the failed capture of the constexpr var in the lambda https://learn.microsoft.com/en-us/cpp/build/reference/zc-lambda?view=msvc-170 . However the syntax error: 'template' remains on this line (and several others):

   xtensor/include/xtensor/xassign.hpp

   Line 1252 in 8c0a484

   res_stepper.template store_simd(fct_stepper.template step_simd<value_type>());

   👍React with 👍1Reacted by Bruno Cabral

   👀React with 👀1Reacted by Jordão Bragantini
9. spectre-ns commented on Jul 19, 2024

   

   spectre-ns

   on Jul 19, 2024

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   Hi @PerretB I have not found a workaround. It works in clang and GCC so it is a compiler issue...

   👍React with 👍1Reacted by Bruno Cabral
10. brccabral commented on Sep 25, 2024

    

    brccabral

    on Sep 25, 2024

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    This small example triggers the error

    #include <xtensor/xarray.hpp>
    #include <xtensor/xrandom.hpp>
    #include <xtensor-blas/xlinalg.hpp>
    
    int main()
    {
        auto W1 = xt::random::rand<float>({10, 50}) - 0.5f;
        auto X = xt::random::rand<float>({10, 50}) - 0.5f;
        xt::xarray<float> d1 = xt::linalg::dot(W1, X);
    
        return 0;
    }

    cmake_minimum_required(VERSION 3.14)
    project(xt_tbb)
    
    set(XTENSOR_USE_XSIMD 1)
    set(XTENSOR_USE_TBB 1)
    find_package(xtensor REQUIRED)
    find_package(xtensor-blas REQUIRED)
    
    add_executable(xt_tbb main.cpp)
    target_compile_options(xt_tbb PUBLIC "/Zc:lambda")
    target_include_directories(xt_tbb PUBLIC ${xtensor-blas_INCLUDE_DIRS})
    target_link_libraries(xt_tbb PUBLIC xtensor)

    C:\Program Files (x86)\xtensor\include\xtensor\xassign.hpp(1252,41): error C2187: syntax error: 'template' was unexpected here