Is anyone else seeing this in a GHC build

utils/hsc2hs/HSCParser.hs:170:14: error: [-Wunused-matches, -Werror=unused-matches]

    Defined but not used: ‘d’

    |

170 |         '\'':d:'\'':_ -> do any3Chars_; text -- Case 2

    |              ^

Indeed, d looks unused.  But this line of code has been there since 28 Dec, so I can’t understand why it has not bitten before.

With -Werror my build fails.  I could switch to -Wwarn, but I think -Werror is the default.

Simon