Something strange going on with statically built GHCs, TH and flushing

If you have a splice which writes to stdout on Windows (or more generally when static linking, see #20791 (comment 402740)) then for some reason the output doesn't show up on CI unless you explicitly flush.

For example

-- () will not be printed
$(liftIO $ print ())

If you add a flush then it works

-- () will be printed
$(liftIO $ print () >> hFlush stdout)