Different Lib/CMake Layout between Pre-Build-Binaries and Build from source

From: Dennis Luehring (dl.soluz_at_[hidden])
Date: 2021-07-26 08:08:33

target_link_libaries(... Boost::boost) seems not to work if the
stagedir/<lib> folder is missing

but the pre-build binaries missing this folder

https://sourceforge.net/projects/boost/files/boost-binaries/1.75.0/
https://sourceforge.net/projects/boost/files/boost-binaries/1.75.0/boost_1_75_0-msvc-14.1-64.exe
boost_1_75_0
    <boost>
    ...
    bootstrap.bat
    bootstrap.sh
    <lib64-msvc-14.1>
      <cmake>
      *.lib

if i build 1.75.0 from source with

b2 --toolset=msvc-14.1 --stagedir=./lib64-msvc-14.1 address-model=64
architecture=x86 link=static threading=multi

i've get this hierachy

c:\Boost\boost_1_75_0
    <boost>
    ...
    bootstrap.bat
    bootstrap.sh
    ...
    <lib64-msvc-14.1> <-- stagedir
      <lib>
        <cmake>
        *.lib

what is the very same hierarchy with Qt6 cmake-configs (so its seems to
be "more" standard)

C:\Qt\6.1.2
   <msvc2017_64> <-- aka "stagedir"
     <lib>
       <cmake>
       Qt6*.lib

why does the pre build binary package got a different hierarchy?