Okay, maybe one more question for the next poor soul that has the same-ish issue
 
Why does this work:
 
*** Prior to bitbake ***
 
export ABC="AAAAAAAAAAAAAAAHHHHHHHHHHHHHHH"
export BB_ENV_PASSTHROUGH_ADDITIONS="$BB_ENV_PASSTHROUGH_ADDITIONS ABC"
 
*** bitbake recipe ***
....
do_configure () {
    export ABC=${ABC} && cmake_do_configure } <<<--- Obviously referencing and seeing ${ABC}
....
 
CMAKE configures and compiles successfully
 
but this doesn't
 
*** bitbake recipe ***
....
do_configure () {
    cmake_do_configure <<<---  ${ABC} doesn't make it to cmake
}
....
 
*** cmakelists.txt ***
 
if( NOT DEFINED ENV{ABC})
    message(FATAL_ERROR "Undefined environmental variable: ABC\n")
endif()
 
*** bitbake output ***
....
| DEBUG: Executing shell function do_configure
....
 
*** cmake output ***
| CMake Error at CMakeLists.txt:12 (message):
|   Undefined environmental variable: ABC
 
 
 
Even doing something like the following makes it visible to CMAKE
 
SOME_VAR = "${ABC}"
do_configure () {
  export ABC=${SOME_VAR} && cmake_do_configure
}