Add smell for limitting the number of explicit imports

data/import_explicit_limit.yaml

@@ -0,0 +1,3 @@
+- smell:
+    type: many explicit imports
+    limit: 2

src/Config/Type.hs

@@ -166,14 +166,15 @@ data Restrict = Restrict
     ,restrictMessage :: Maybe String
     } deriving Show
 
-data SmellType = SmellLongFunctions | SmellLongTypeLists | SmellManyArgFunctions | SmellManyImports
+data SmellType = SmellLongFunctions | SmellLongTypeLists | SmellManyArgFunctions | SmellManyImports | SmellManyExplicitImports
   deriving (Show,Eq,Ord)
 
 getSmellType :: String -> Maybe SmellType
 getSmellType "long functions" = Just SmellLongFunctions
 getSmellType "long type lists" = Just SmellLongTypeLists
 getSmellType "many arg functions" = Just SmellManyArgFunctions
 getSmellType "many imports" = Just SmellManyImports
+getSmellType "many explicit imports" = Just SmellManyExplicitImports
 getSmellType _ = Nothing
 
 data Setting

src/Hint/Smell.hs

@@ -74,6 +74,20 @@ import A
 import A; import B
 import A
 </TEST>
+
+<TEST> [{smell: { type: many explicit imports, limit: 2}}]
+import A (x, y, z) --
+import A (x, y)
+import A
+import A hiding (x, y, z)
+</TEST>
+
+<TEST>
+import A (x, y, z)
+import A (x, y)
+import A
+import A hiding (x, y, z)
+</TEST>
 -}
 
 import Hint.Type(ModuHint,ModuleEx(..),DeclHint,Idea(..),rawIdea,warn)
@@ -93,17 +107,34 @@ import Language.Haskell.GhclibParserEx.GHC.Utils.Outputable
 smellModuleHint :: [Setting] -> ModuHint
 smellModuleHint settings scope m =
   let (L _ mod) = ghcModule m
-      imports = hsmodImports mod in
-  case Map.lookup SmellManyImports (smells settings) of
+      imports = hsmodImports mod
+      sm = smells settings in
+  manyImportsHint sm imports ++
+  concatMap (explicitImportLengthHint sm) imports
+
+manyImportsHint :: Map.Map SmellType Int -> [LImportDecl GhcPs] -> [Idea]
+manyImportsHint sm imports =
+  case Map.lookup SmellManyImports sm of
     Just n | length imports >= n ->
              let span = foldl1 combineSrcSpans $ locA . getLoc <$> imports
                  displayImports = unlines $ f <$> imports
-             in [rawIdea Config.Type.Warning "Many imports" span displayImports  Nothing [] [] ]
+             in [rawIdea Config.Type.Warning "Many imports" span displayImports Nothing [] []]
       where
         f :: LImportDecl GhcPs -> String
         f = trimStart . unsafePrettyPrint
     _ -> []
 
+explicitImportLengthHint :: Map.Map SmellType Int -> LImportDecl GhcPs -> [Idea]
+explicitImportLengthHint sm imp@(L _ decl) =
+  case Map.lookup SmellManyExplicitImports sm of
+    Just limit ->
+      case ideclImportList decl of
+        Just (Exactly, L _ names) | length names > limit ->
+          [rawIdea Config.Type.Warning "Too many explicit imports" (locA $ getLoc imp)
+            (trimStart $ unsafePrettyPrint imp) Nothing [] []]
+        _ -> []
+    Nothing -> []
+
 smellHint :: [Setting] -> DeclHint
 smellHint settings scope m d =
   sniff smellLongFunctions SmellLongFunctions ++

tests/import_explicit_limit.test

@@ -0,0 +1,35 @@
+---------------------------------------------------------------------
+RUN tests/import_explicit_limit_pos.hs --hint=data/import_explicit_limit.yaml
+FILE tests/import_explicit_limit_pos.hs
+import A (sort, nub, group)
+import B (Map, lookup, insert)
+OUTPUT
+tests/import_explicit_limit_pos.hs:1:1-27: Warning: Too many explicit imports
+Found:
+  import A ( sort, nub, group )
+
+tests/import_explicit_limit_pos.hs:2:1-30: Warning: Too many explicit imports
+Found:
+  import B ( Map, lookup, insert )
+
+2 hints
+
+---------------------------------------------------------------------
+RUN tests/import_explicit_limit_default.hs
+FILE tests/import_explicit_limit_default.hs
+import A (sort, nub, group)
+import B (Map, lookup, insert)
+OUTPUT
+No hints
+
+---------------------------------------------------------------------
+RUN tests/import_explicit_limit_neg.hs --hint=data/import_explicit_limit.yaml
+FILE tests/import_explicit_limit_neg.hs
+import A (sort, nub)
+import B (sort)
+import C
+import D hiding (sort, nub, group)
+OUTPUT
+No hints
+
+---------------------------------------------------------------------