Isn't lint/splint just used for static code analysis? If that's true, then something like scan-build(1) from devel/llvm might work, and you might already have it installed. apropos scan-build should help to find which to use if you have something like devel/llvm80 or devel/llvm90 installed.
And then there's this commercial tool available for FreeBSD developers via Phabricator?
Years ago I had a cheap license for Sniff++, a very sophisticated tool for static code analysis. Unfortunately it doesn't exist anymore. Does anyone know of anything similar?