Fix support for oneTBB new inteface >= v2021.1

[jeanchristopheruel]

Submitting a support for oneTBB new interface. I suggest that this should be tested with a proper CI/CD.
oneTBB library do not provide <tbb/tbb_stddef.h> anymore as can be seen here. It is now replaced by <tbb/tbb.h> since v2021.1.

[WardBrian]

I believe __has_include is only available for C++17, while Stan still supports C++14 as a minimum.

Are you defining TBB_INTERFACE_NEW during compilation? That is required to use Stan-math with TBB 2021

[jeanchristopheruel]

Instead of relying on the makefile, I use CMake's FetchContent to integrate Stan-math into my project as a module. This approach streamlines the build process and eliminates the need to install unused components, allowing greater flexibility in managing dependencies.

I could find related interest in using FetchContent + CMakeList.txt in #2967

include(FetchContent)
FetchContent_Declare(
     stanmath
     GIT_REPOSITORY https://github.com/jeanchristopheruel/math
     GIT_TAG develop
     GIT_SHALLOW TRUE
     )
FetchContent_MakeAvailable(stanmath)

find_package(Boost 1.81.0 REQUIRED)
find_package(TBB 2021 REQUIRED)
find_package(Eigen3 3.4 REQUIRED)

add_library(stan-math INTERFACE)
target_link_libraries(stan-math INTERFACE Eigen3::Eigen TBB::tbb -lstdc++ -lm)
target_include_directories(stan-math INTERFACE ${stanmath_SOURCE_DIR} ${Boost_INCLUDE_DIRS})
add_library(stan::math ALIAS stan-math)

[WardBrian]

#2967 is definitely the right place to discuss CMake, and I'm hoping we can support it sooner rather than later.

In the mean time, you should still be using target_compile_definitions or just add_compile_options to define TBB_INTERFACE_NEW as the way of selecting to use newer versions

[jeanchristopheruel]

Thanks for your time. I will do so. However, it still wont support TBB_VERSION_MAJOR == 2021. Current statement for #if TBB_VERSION_MAJOR >= 2020 will fail.

[WardBrian]

We use TBB 2021 for the conda-forge builds of cmdstan with this. If you can share the error you are getting I can try to help debug it, but it is definitely possible to use newer TBBs without source changes

[jeanchristopheruel]

OneApi TBB does not have tbb_stddef.h anymore. TBB might?
Migration guide TBB -> OneApi TBB

[WardBrian]

If you define TBB_INTERFACE_NEW, that header will not be included by Stan Math

[jeanchristopheruel]

Indeed, as you previously pointed out. My apologies.
Closing issue.