If I didn’t use --variables-files=etc/scons/propagate_shell_environment.vars in command line then I used to get below error:
[root@portal4 mongo-r3.6.9]# python buildscripts/scons.py all
scons: Reading SConscript files ...
scons version: 2.5.0
python version: 2 7 5 'final' 0
Checking whether the C compiler works... yes
Checking whether the C++ compiler works... yes
Checking that the C++ compiler can link a C++ program... yes
Checking if C++ compiler "g++" is GCC... yes
Checking if C compiler "gcc" is GCC... yes
Detected a x86_64 processor
Checking if target OS linux is supported by the toolchain... yes
Checking if C compiler is GCC 5.3.0 or newer...no
Checking if C++ compiler is GCC 5.3.0 or newer...no
ERROR: Refusing to build with compiler that does not meet requirements
See /root/mongoCompilation_TagCode/mongo-r3.6.9/build/scons/config.log for details
And now as per your suggestion, now started clean compilation with below command
python buildscripts/scons.py MONGO_VERSION=3.6.9 MONGO_GIT_HASH=unknown CC=$HOME/gcc/bin/gcc CXX=$HOME/gcc/bin/g++