While FreeBSD and OpenBSD both switched to using LLVM/Clang as their base system compiler, NetBSD picked a different path and remained with GCC and binutils regardless of the license change to GPLv3. However, it doesn't mean that the NetBSD project endorses this license, and the NetBSD Foundation's has issued a statement about its position on the subject.
Realistically, NetBSD is more or less tied to GCC, as it supports more architectures than the other BSDs, some of which will likely never be supported in LLVM.
As of NetBSD 9.1, the latest released version, all supported platforms have recent versions of GCC (7.5.0) and binutils (2.31.1) in the base system. Newer (and older!) versions of GCC can be installed via Pkgsrc, and the following packages are available, going all the way back to GCC 3.3.6:
+---------+------------+-------------------+ | Package | Version | Release date | +---------+------------+-------------------+ | gcc10 | GCC 10.2.0 | July 23, 2020 | | gcc9 | GCC 9.3.0 | March 12, 2020 | | gcc8 | GCC 8.4.0 | March 4, 2020 | | gcc7 | GCC 7.5.0 | November 14, 2019 | | gcc6 | GCC 6.5.0 | October 26, 2018 | | gcc5 | GCC 5.5.0 | October 10, 2017 | | gcc49 | GCC 4.9.4 | August 3, 2016 | | gcc48 | GCC 4.8.5 | June 23, 2015 | | gcc3 | GCC 3.3.6 | May 3, 2005 | +---------+------------+-------------------+
The focus on GCC doesn't mean that the GNU and LLVM toolchains cannot coexist within NetBSD, and work has in fact been done during the last decade to make it happen.
Despite currently not being built by default in official NetBSD releases, LLVM has been imported in the NetBSD source tree in 2013. Daily images are built from NetBSD-current for selected platforms (at least amd64, i386 and evbarm) with the MKLLVM and HAVE_LLVM build options enabled, and contain LLVM and Clang.
Moreover, NetBSD has invested a lot of work on LLVM during the past few years, including funding some developer contracts for Kamil Rytarowski (kamil@) and Michał Górny (mgorny@), which allowed them to work on various parts of the LLVM toolchain to add and enhance support for sanitizers, and to improve LLDB support.
They both published several dozen articles on the NetBSD blog along the way, retracing their journey. Kamil's final report about upstreaming support to LLVM sanitizers summarizes the work accomplished. Thanks to this work, sanitizer support on NetBSD is mature and mostly on par with Linux. As a result, because LLVM is upstream for GCC sanitizers, they are also available in GCC on NetBSD. Similarly, Michał's final report on his LLDB work details the achievements on the debuggers front.
As always, work continues towards keeping the toolchains up to date, and upstreaming local changes whenever possible.