Change how dependencies on sublibraries are printed

Changelog.md

@@ -1,3 +1,26 @@
+# 0.1.11
+
+- Change how dependencies on (multiple) sublibraries are output:
+  Always print each sublibrary on individual line,
+  with the first one having the version range.
+
+  ```cabal
+  build-depends:
+    ...
+    , megalib              >=0.1 && <0.2
+    , megalib:sublib-a
+    , megalib:sublib-b
+    , megalib:sublib-c
+  ```
+
+  instead of previous
+
+  ```
+  build-depends:
+    ...
+    , megalib:{megalib, sublib-a, sublib-b, sublib-c} >=0.1 && <0.2
+  ```
+
 # 0.1.10
 
 - Fix removal of empty lines in free text fields (like `description`)

cabal-fmt.cabal

@@ -1,6 +1,6 @@
 cabal-version:      2.2
 name:               cabal-fmt
-version:            0.1.10
+version:            0.1.11
 synopsis:           Format .cabal files
 category:           Development
 description:

fixtures/sublib.cabal

@@ -0,0 +1,23 @@
+cabal-version:      3.0
+name:               sublib
+version:            0
+
+library
+  default-language: Haskell2010
+  hs-source-dirs:   src
+
+  -- the anotherlib case tests case insensitivity.
+  build-depends:
+      base        >=4.3   && <4.18
+    , megalib
+    , megalib:sublib-a >=0.1
+    , megalib:sublib-b <0.3
+    , megalib:sublib-c <0.2
+
+    , anotherlib:sublib-B <0.3
+    , anotherlib:sublib-a >=0.1
+    , anotherlib:sublib-C <0.2
+
+  exposed-modules:
+    Data.ExampleA
+    Data.ExampleB

fixtures/sublib.format

@@ -0,0 +1,22 @@
+cabal-version: 3.0
+name:          sublib
+version:       0
+
+library
+  default-language: Haskell2010
+  hs-source-dirs:   src
+
+  -- the anotherlib case tests case insensitivity.
+  build-depends:
+    , anotherlib:sublib-a  >=0.1 && <0.2
+    , anotherlib:sublib-B
+    , anotherlib:sublib-C
+    , base                 >=4.3 && <4.18
+    , megalib              >=0.1 && <0.2
+    , megalib:sublib-a
+    , megalib:sublib-b
+    , megalib:sublib-c
+
+  exposed-modules:
+    Data.ExampleA
+    Data.ExampleB

fixtures/with-sublibs.format

@@ -1,4 +1,3 @@
-Up to date
 cabal-version: 3.0
 name:          with-sublibs
 version:       1
@@ -7,14 +6,21 @@ library
   hs-source-dirs:   src
   default-language: Haskell2010
   build-depends:
-    , test1:{test1, sub}
-    , test2:{test2, sub}  >=2 && <3
+    , test1
+    , test1:sub
+    , test2      >=2 && <3
+    , test2:sub
 
   build-depends:    test1
   build-depends:    test2 >=1
   build-depends:    test2:sub
   build-depends:    test2:sub
-  build-depends:    test2:{sub1, sub2}
+  build-depends:
+    , test2:sub1
+    , test2:sub2
+
   build-depends:    test2:sub >=1 && <3
   build-depends:    test2:sub >=2 && <3
-  build-depends:    test2:{sub1, sub2} >=3 && <4
+  build-depends:
+    , test2:sub1  >=3 && <4
+    , test2:sub2

src/CabalFmt/Fields/BuildDepends.hs

@@ -11,20 +11,22 @@ module CabalFmt.Fields.BuildDepends (
 
 import Data.List (dropWhileEnd)
 
+import           CabalFmt.Fields
+import           CabalFmt.Options
+import           CabalFmt.Prelude
 import qualified Distribution.CabalSpecVersion    as C
+import qualified Distribution.Compat.NonEmptySet  as NES
 import qualified Distribution.FieldGrammar        as C
 import qualified Distribution.Parsec              as C
 import qualified Distribution.Pretty              as C
 import qualified Distribution.Types.Dependency    as C
 import qualified Distribution.Types.DependencyMap as C
 import qualified Distribution.Types.ExeDependency as C
+import qualified Distribution.Types.LibraryName   as C
 import qualified Distribution.Types.VersionRange  as C
 import qualified Text.PrettyPrint                 as PP
-
-import CabalFmt.Fields
-import CabalFmt.Options
-import CabalFmt.Prelude
-import VersionInterval  (normaliseVersionRange, ConversionProblem (..))
+import           VersionInterval
+                 (ConversionProblem (..), normaliseVersionRange)
 
 setupDependsF :: Options -> FieldDescrs () ()
 setupDependsF opts = singletonF "setup-depends" (pretty opts) parse
@@ -48,7 +50,7 @@ normaliseVersionRange' vr = either fromConversionProblem id (normaliseVersionRan
     fromConversionProblem OtherConversionProblem = vr
 
 pretty :: Options -> [C.Dependency] -> PP.Doc
-pretty opts deps = case deps of
+pretty opts deps = case deps' of
     []    -> PP.empty
     [dep] -> PP.text (prettyDepNoVersion dep) PP.<+> prettyVR vr'
       where
@@ -58,18 +60,33 @@ pretty opts deps = case deps of
                     | vr == C.noVersion  = PP.text "<0"
                     | otherwise          = C.pretty vr
 
-    _ -> prettyMany opts deps'
+    _ -> prettyMany opts deps''
       where
-        deps' :: [(String, C.VersionRange)]
-        deps' = sortOn (map toLower . fst)
-              $ map (prettyDepNoVersion &&& C.depVerRange)
-              $ C.fromDepMap . C.toDepMap -- this combines duplicate packages
-              $ deps
+        deps'' :: [(String, C.VersionRange)]
+        deps'' =
+            sortOn (map toLower . fst) $
+            map (prettyDepNoVersion &&& C.depVerRange) deps'
     where
+      -- combined and expanded dependencies
+      deps' :: [C.Dependency]
+      deps' = concatMap expandDep $ C.fromDepMap $ C.toDepMap deps
+
       prettyDepNoVersion :: C.Dependency -> String
       prettyDepNoVersion (C.Dependency pkg _ libs) =
         C.prettyShow (C.Dependency pkg C.anyVersion libs)
 
+      expandDep :: C.Dependency -> [C.Dependency]
+      expandDep (C.Dependency pkg vr libs) = makeDep $ sortOn f (NES.toList libs)
+        where
+          f C.LMainLibName    = Nothing
+          f (C.LSubLibName n) = Just (map toLower (C.prettyShow n))
+
+          -- attach version range to the first dependency of the group.
+          makeDep :: [C.LibraryName] -> [C.Dependency]
+          makeDep []         = []
+          makeDep (ln : lns) =
+              C.Dependency pkg vr (NES.singleton ln) :
+              map (\ln' -> C.Dependency pkg C.anyVersion (NES.singleton ln')) lns
 
 prettyExe :: Options -> [C.ExeDependency] -> PP.Doc
 prettyExe opts deps = case deps of

tests/golden.hs

@@ -33,6 +33,9 @@ main = defaultMain $ testGroup "tests"
 
     , goldenTest' "issue69"
     , goldenTest' "issue29"
+
+    , goldenTest' "sublib"
+    , goldenTest' "with-sublibs"
     ]
 
 goldenTest' :: String -> TestTree