Fix the build with ghc-8.2.1. (#147)

- Avoid using a deprecated Cabal function
- Use newer versions of proto-lens packages in stack.yaml
- Work around a new type-level warning that affects `OneOf/TensorTypes`.

stack.yaml

@@ -20,7 +20,8 @@ extra-deps:
 - proto-lens-protobuf-types-0.2.2.0
 - proto-lens-0.2.2.0
 - proto-lens-descriptors-0.2.2.0
-- proto-lens-protoc-0.2.2.1
+- proto-lens-protoc-0.2.2.3
+- lens-labels-0.1.0.2
 
 # For Mac OS X, whose linker doesn't use this path by default
 # unless you run `xcode-select --install`.

tensorflow-core-ops/Setup.hs

@@ -11,6 +11,7 @@
 -- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 -- See the License for the specific language governing permissions and
 -- limitations under the License.
+{-# LANGUAGE CPP #-}
 
 -- | Generates the wrappers for Ops shipped with tensorflow.
 module Main where
@@ -20,7 +21,7 @@ import Distribution.PackageDescription
     , libBuildInfo
     , hsSourceDirs
     )
-import Distribution.Simple.BuildPaths (autogenModulesDir)
+import qualified Distribution.Simple.BuildPaths as BuildPaths
 import Distribution.Simple.LocalBuildInfo (LocalBuildInfo)
 import Distribution.Simple
     ( defaultMainWithHooks
@@ -91,3 +92,10 @@ blackList =
     [ -- Requires the "func" type:
       "SymbolicGradient"
     ]
+
+autogenModulesDir :: LocalBuildInfo -> FilePath
+#if MIN_VERSION_Cabal(2,0,0)
+autogenModulesDir = BuildPaths.autogenPackageModulesDir
+#else
+autogenModulesDir = BuildPaths.autogenModulesDir
+#endif

tensorflow/src/TensorFlow/Types.hs

@@ -19,6 +19,7 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE MonoLocalBinds #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RankNTypes #-}
@@ -453,10 +454,10 @@ infixr 5 /:/
 --
 -- using an enumeration of all the possible 'TensorType's.
 type OneOf ts a
-    -- Assert `TensorTypes ts` to make error messages a little better.
-    = (TensorType a, TensorTypes ts, NoneOf (AllTensorTypes \\ ts) a)
+    -- Assert `TensorTypes' ts` to make error messages a little better.
+    = (TensorType a, TensorTypes' ts, NoneOf (AllTensorTypes \\ ts) a)
 
-type OneOfs ts as = (TensorTypes as, TensorTypes ts,
+type OneOfs ts as = (TensorTypes as, TensorTypes' ts,
                         NoneOfs (AllTensorTypes \\ ts) as)
 
 type family NoneOfs ts as :: Constraint where
@@ -486,6 +487,29 @@ instance TensorTypes '[] where
 instance (TensorType t, TensorTypes ts) => TensorTypes (t ': ts) where
     tensorTypes = TensorTypeProxy :/ tensorTypes
 
+-- | A simpler version of the 'TensorTypes' class, that doesn't run
+-- afoul of @-Wsimplifiable-class-constraints@.
+--
+-- In more detail: the constraint @OneOf '[Double, Float] a@ leads
+-- to the constraint @TensorTypes' '[Double, Float]@, as a safety-check
+-- to give better error messages.  However, if @TensorTypes'@ were a class,
+-- then GHC 8.2.1 would complain with the above warning unless @NoMonoBinds@
+-- were enabled.  So instead, we use a separate type family for this purpose.
+-- For more details: https://ghc.haskell.org/trac/ghc/ticket/11948
+type family TensorTypes' (ts :: [*]) :: Constraint where
+    -- Specialize this type family when `ts` is a long list, to avoid deeply
+    -- nested tuples of constraints.  Works around a bug in ghc-8.0:
+    -- https://ghc.haskell.org/trac/ghc/ticket/12175
+    TensorTypes' (t1 ': t2 ': t3 ': t4 ': ts)
+        = (TensorType t1, TensorType t2, TensorType t3, TensorType t4
+              , TensorTypes' ts)
+    TensorTypes' (t1 ': t2 ': t3 ': ts)
+        = (TensorType t1, TensorType t2, TensorType t3, TensorTypes' ts)
+    TensorTypes' (t1 ': t2 ': ts)
+        = (TensorType t1, TensorType t2, TensorTypes' ts)
+    TensorTypes' (t ': ts) = (TensorType t, TensorTypes' ts)
+    TensorTypes' '[] = ()
+
 -- | A constraint checking that two types are different.
 type family a /= b :: Constraint where
     a /= a = TypeError a ~ ExcludedCase
@@ -529,7 +553,7 @@ type family as \\ bs where
 -- Assumes that @a@ and each of the elements of @ts@ are 'TensorType's.
 type family NoneOf ts a :: Constraint where
     -- Specialize this type family when `ts` is a long list, to avoid deeply
-    -- nested tuples of constraints.  Works around a bug in ghc-8:
+    -- nested tuples of constraints.  Works around a bug in ghc-8.0:
     -- https://ghc.haskell.org/trac/ghc/ticket/12175
     NoneOf (t1 ': t2 ': t3 ': t4 ': ts) a
         = (a /= t1, a /= t2, a /= t3, a /= t4, NoneOf ts a)