Well, the whole purpose of OpenMP is to be a syntactically lightweight way of parallelizing code; it is a well supported standard. C++17 in fact has paralel extensions to the standard library, but if you have access to OpenMP it is often better.

OpenMP is not C++ specific, it is also supported in fortran and C (although the newer OpenMP standards have first class support for C++ iterator semantics). In principle it could also be supported in rust although I assume that making it work with the borrow checker might not be easy.