Issue with Intel compilation on macOS 10.15 Catalina : catastrophic error: cannot open source file "stdlib.h" - c++

Question

I try desperatly to compile with c++ intel compiler (icpc) a simple code that I was used to compile on my previous macBook 10.14.
Now, since Headers don't exist anymore with 10.15 Catalina, the compiler has difficulties to find stdlib.h. Here the output I get :
icpc -std=c++11 -O3 -xHost -fp-model strict -prec-div -prec-sqrt -fma -ftz -mp1 -qopenmp -Wall -c -I/opt/intel/compilers_and_libraries_2020.2.258/mac/mkl/include -mkl=parallel main.cpp -o main.o
In file included from /Library/Developer/CommandLineTools/usr/include/c++/v1/math.h(301),
from /opt/intel/compilers_and_libraries_2020.2.258/mac/compiler/include/math.h(177),
from /Library/Developer/CommandLineTools/usr/include/c++/v1/cmath(304),
from TSAF.h(1),
from main.cpp(1):
/Library/Developer/CommandLineTools/usr/include/c++/v1/stdlib.h(20): catastrophic error: cannot open source file "stdlib.h"
#include_next <stdlib.h>
^
compilation aborted for main.cpp (code 4)
make: *** [Makefile:13: main.o] Error 4
./main_intel.exe: No such file or directory
I tried a lot of potential workarounds from the net but none works. I would like to avoid to create a directory /usr/include/ by removing the security system of my macBook.
I thought maybe this would work by downloading XCode_12.0.1 but same problems remain.
For the moment, I have the version Catalina OS 10.15.7, all has been updated.
EDIT 1: There is something that I don't understand : on my previous macBook 10.14, I didn't need to use the headers of clang c++ for intel compilation.
If anyone could give me a suggestion/clue/track, this would be fine.

Answer 1

Run the command in the Terminal
sudo xcode-select --reset
And then check if proper developer tools are selected instead of the command line tools
xcode-select -p