is there a way to tell pants to treat warnings as errors? in our CI/CD if a change introduces warnings I'd like the job to fail

which warnings? each tool pants runs has its own config. Some language backends have independent settings, such as the Python backend's unowned dependency behavior

in this case it was unmatched globs -- someone had copied a BUILD file including a

python_tests()

rule to a package that didn't have tests. They didn't catch it in CI/CD since the WARN lines aren't really obvious there; all the tests did pass.

probably unmatched build file globs setting is the one you'd want for that

so I'm inferring that I can turn these specific warnings into errors, but can't easily just say to exit with a nonzero if any warnings are emitted

yes, unfortunately. we don't have a global "default error behaviour" toggle (or even a list of all the places that have toggleable error behaviour). Although, that would be neat