What happened to header files after Catalina update? I am getting the error "assert.h:No such file or directory". In Mojave this issue was solved by using macOS_SDK_headers_for_macOS_10.14.pkg package. Is there any such package for 10.15 or any other solution? Is anyone else facing this issue?
Recently I also updated to Catalina and got the same problem. As it was mentioned there is no equivalent package macOS_SDK_headers_for_macOS_10.14.pkg for Mac OS 10.15 which solves the problem for Mojave.
There are several things you can do which worked for me.
Some answers recommend to agree with the license. I'm not sure if it's helpful but I did it anyway
sudo xcodebuild -license
and type agree.
Apparently you can find these headers in a /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include directory. So you can add it to some environment/build system variable.