Binary package “libclang-9-dev” in ubuntu focal

Clang library - Development package

 Clang project is a C, C++, Objective C and Objective C++ front-end
 based on the LLVM compiler. Its goal is to offer a replacement to the
 GNU Compiler Collection (GCC).
 .
 Clang implements all of the ISO C++ 1998, 11 and 14 standards and also
 provides most of the support of C++17.
 .
 This package contains the Clang headers to develop extensions over
 libclang1-9.