updCtxt upd = updLclEnv (\ env@(TcLclEnv { tcl_ctxt = ctxt }) ->
env { tcl_ctxt = upd ctxt })
--- Conditionally add an error context
-maybeAddErrCtxt :: Maybe Message -> TcM a -> TcM a
-maybeAddErrCtxt (Just msg) thing_inside = addErrCtxt msg thing_inside
-maybeAddErrCtxt Nothing thing_inside = thing_inside
-
popErrCtxt :: TcM a -> TcM a
popErrCtxt = updCtxt (\ msgs -> case msgs of { [] -> []; (_ : ms) -> ms })