best way to detect invalid Haddock early?

[Norman Ramsey]

I've had some CI failures because of invalid Haddock comments.  What
is the best way to detect such issues locally, early?  I tried setting
environment variable GHC_FLAGS to "-Winvalid-haddock", which should
have told `./hadrian/ghci` to issue a warning.  But for some reason,
no warning was issued.

What's a good way to detect invalid Haddock before it hits CI?


Norman