Add functor-classes-compat

build-constraints.yaml

@@ -1107,6 +1107,7 @@ packages:
         - binary-tagged
         - cabal-doctest
         - edit-distance
+        - functor-classes-compat
         - generics-sop-lens
         - github
         - insert-ordered-containers
@@ -3048,6 +3049,10 @@ package-flags:
         ghc_7_7: false
         ghc_8_0: true
 
+    functor-classes-compat:
+        containers: false
+        unordered-containers: false # https://github.com/fpco/stackage/issues/2386
+
 # end of package-flags
 
 # Special configure options for individual packages