install error of threads-0.5.0.2

error

Configuring threads-0.5.0.2...
Building threads-0.5.0.2...
Preprocessing library threads-0.5.0.2...

Control/Concurrent/Thread.hs:129:30:
     warning: \u used with no following hex digits; treating as '\' followed by identifier [-Wunicode]
              doForkWithUnmask $ \unmask →
                                 ^

Control/Concurrent/Thread.hs:139:12:
     warning: missing terminating ' character [-Winvalid-pp-token]
-- and wasn't catched or the actual value that was returned by the thread.
           ^
2 warnings generated.

Control/Concurrent/Thread/Group.hs:6:4:
     error: invalid preprocessing directive
      #-}
       ^

Control/Concurrent/Thread/Group.hs:182:24:
     warning: \u used with no following hex digits; treating as '\' followed by identifier [-Wunicode]
        doForkWithUnmask $ \unmask → do
                           ^
1 warning and 1 error generated.
Failed to install threads-0.5.0.2
cabal: Error: some packages failed to install:
threads-0.5.0.2 failed during the building phase. The exception was:
ExitFailure 1