Faulty toolset specification in bootstrap.sh / build.sh

I tried to compile boost with the latest intel compiler release (oneapi/Intel-2021.4) both with icpx and icpc.

I spotted 3 main issues:

1) Specifying any intel toolset version is currently faulty due to the mechanism in build.sh. Here, in the function check_toolset, the toolset string is split based on - and in the function test_toolset only the first part is then compared against the input. Meaning that the function compares intel with its input, which is always intel-linux or linux-darwin. The function then runs through and guesses the toolset.

2) not specifying a toolset correctly identifies in my case the intel-linux within the tools/build/src/engine/build.sh script if I have the intel oneapi at the default location (/opt/intel/.....), but the correctly identified toolset is not returned to bootstrap.sh, because the $TOOLSET variable is not altered, but kept empty. This leads to a faulty project-config.jam file:

if !  in [ feature.values <toolset> ]
{
    using  ;   
}

project : default-build <toolset> ;

I get the same file with the procedure in 1), because the TOOLSET variable is set empty by build.sh?

3) For the bootstrap/build pipeline the CXXFLAGS env variable is currently ignored. build.sh supports it as a command line argument, but does not check the env variable and bootstrap does not give the env variable to the build script as an argument. The CXXFLAGS should be supported for some "non-default" location setups.

All of this is easy to change, but I am confused that there are so many dangling variables, so I am not sure whether I understood this correctly as written here (but some quick fixes were able to fix the pipeline as expected)

boostorg / build

Faulty toolset specification in bootstrap.sh / build.sh #743