Add -Werror=unused-packages option

Author: phadej

src/HaskellCI/Config/Grammar.hs

@@ -163,6 +163,8 @@ configGrammar = Config
         ^^^ help "Don't insert the haskell-ci version into the generated Travis YAML file"
     <*> optionalFieldDef "error-missing-methods"                                            (field @"cfgErrorMissingMethods") defaultConfig
         ^^^ metahelp "PKGSCOPE" "Insert -Werror=missing-methods for package scope (none, local, all)"
+    <*> booleanFieldDef     "error-unused-packages"                                         (field @"cfgErrorUnusedPkgs") defaultConfig
+        ^^^ help "Insert -Werror=unused-packages"
     <*> blurFieldGrammar (field @"cfgDoctest") doctestConfigGrammar defaultConfig
     <*> blurFieldGrammar (field @"cfgDocspec") docspecConfigGrammar defaultConfig
     <*> pure [] -- constraint sets

src/HaskellCI/Config/Initial.hs

@@ -74,6 +74,7 @@ initialConfig = Config
     , cfgGitHubPatches       = []
     , cfgInsertVersion       = True
     , cfgErrorMissingMethods = PackageScopeLocal
+    , cfgErrorUnusedPkgs     = True -- TODO: False
     , cfgDoctest             = initialDoctestConfig
     , cfgDocspec             = initialDocspecConfig
     , cfgConstraintSets      = []

src/HaskellCI/Config/Type.hs

@@ -74,6 +74,7 @@ data Config = Config
     , cfgGitHubPatches       :: [FilePath]
     , cfgInsertVersion       :: !Bool
     , cfgErrorMissingMethods :: !PackageScope
+    , cfgErrorUnusedPkgs     :: !Bool
     , cfgDoctest             :: !DoctestConfig
     , cfgDocspec             :: !DocspecConfig
     , cfgConstraintSets      :: [ConstraintSet]

src/HaskellCI/GitHub.hs

@@ -350,12 +350,17 @@ makeGitHub _argv config@Config {..} gitconfig prj jobs@JobVersions {..} = do
                 PackageScopeLocal -> for_ pkgs $ \Pkg{pkgName,pkgJobs} -> do
                     let range = Range (C.orLaterVersion (C.mkVersion [8,2])) /\ RangePoints pkgJobs
                     echo_if_to range "cabal.project" $ "package " ++ pkgName
-                    echo_if_to range "cabal.project" $ "    ghc-options: -Werror=missing-methods"
+                    echo_if_to range "cabal.project" $ "    ghc-options: -Werror=missing-methods -Werror=missing-fields"
                 PackageScopeAll   -> cat "cabal.project" $ unlines
                     [ "package *"
                     , "  ghc-options: -Werror=missing-methods -Werror=missing-fields"
                     ]
 
+            when cfgErrorUnusedPkgs $ for_ pkgs $ \Pkg{pkgName,pkgJobs} -> do
+                let range = Range (C.orLaterVersion (C.mkVersion [8,10])) /\ RangePoints pkgJobs
+                echo_if_to range "cabal.project" $ "package " ++ pkgName
+                echo_if_to range "cabal.project" $ "    ghc-options: -Werror=unused-packages"
+
             -- extra cabal.project fields
             cat "cabal.project" $ C.showFields' (const C.NoComment) (const id) 2 $ extraCabalProjectFields "$GITHUB_WORKSPACE/source/"