First noticed here. I haven't managed to boil this down to a test case with no dependencies yet, so for the time being, this requires vector. To reproduce, follow these steps:

$ git clone https://github.com/erikd/vector
$ cd vector/
$ cabal install --only-dependencies --enable-tests -w /opt/ghc/8.2.1/bin/ghc
$ cabal configure --enable-tests -w /opt/ghc/8.2.1/bin/ghc
$ cabal test

When building vector-tests-O2, GHC will stall when compiling the Tests.Vector module. On machines with modest memory allowances (e.g., the machines used on Travis CI), GHC will be killed with an out-of-memory error after trying to compile Tests.Vector for a while.