cabal: Tweak warnings during compilation

Uses two new flags:

  -fdefer-typed-holes: Allows to load code into ghci or use editor
   autocompletion in the presence of typed holes

  - fno-warn-name-shadowing: Removes one annoying type of warnings

osek-verification.cabal

@@ -35,7 +35,7 @@ library
                      , mtl >= 2.2 && <2.3
                      , process >= 1.4 && <1.5
   default-language:    Haskell2010
-  ghc-options:         -Wall
+  ghc-options:         -Wall -fdefer-typed-holes -fno-warn-name-shadowing
 
 executable mockup_generator
   main-is:             Main.hs
@@ -46,7 +46,7 @@ executable mockup_generator
                      , optparse-applicative >= 0.12 && <0.13
   hs-source-dirs:      src/main
   default-language:    Haskell2010
-  ghc-options:         -Wall
+  ghc-options:         -Wall -fdefer-typed-holes -fno-warn-name-shadowing
 
 test-suite spec
   type:                exitcode-stdio-1.0
@@ -71,4 +71,4 @@ test-suite spec
                      , here >= 1.2 && < 1.3
                      , mtl >= 2.2 && <2.3
   default-language:    Haskell2010
-  ghc-options:         -Wall
+  ghc-options:         -Wall -fdefer-typed-holes -fno-warn-name-shadowing