Revert "layoutWL: Don't let indentation result in trailing whitespace (#139)"

This reverts commit 9635a5d.

Fixes #205.

Author: sjakobi

prettyprinter/src/Prettyprinter/Internal.hs

@@ -2073,15 +2073,7 @@ layoutWadlerLeijen
         Empty           -> best nl cc ds
         Char c          -> let !cc' = cc+1 in SChar c (best nl cc' ds)
         Text l t        -> let !cc' = cc+l in SText l t (best nl cc' ds)
-        Line            -> let x = best i i ds
-                               -- Don't produce indentation if there's no
-                               -- following text on the same line.
-                               -- This prevents trailing whitespace.
-                               i' = case x of
-                                   SEmpty  -> 0
-                                   SLine{} -> 0
-                                   _       -> i
-                           in SLine i' x
+        Line            -> SLine i (best i i ds)
         FlatAlt x _     -> best nl cc (Cons i x ds)
         Cat x y         -> best nl cc (Cons i x (Cons i y ds))
         Nest j x        -> let !ij = i+j in best nl cc (Cons ij x ds)

prettyprinter/test/Testsuite/Main.hs

@@ -90,8 +90,6 @@ tests = testGroup "Tests"
             [ testCase "Line" regressionUnboundedGroupedLine
             , testCase "Line within align" regressionUnboundedGroupedLineWithinAlign
             ]
-        , testCase "Indentation on otherwise empty lines results in trailing whitespace (#139)"
-                   indentationShouldntCauseTrailingWhitespaceOnOtherwiseEmptyLines
         , testCase "Ribbon width should be computed with `floor` instead of `round` (#157)"
                    computeRibbonWidthWithFloor
         ]
@@ -395,14 +393,6 @@ regressionUnboundedGroupedLineWithinAlign
         expected = SChar 'x' (SLine 0 (SChar 'y' SEmpty))
     in assertEqual "" expected sdoc
 
-indentationShouldntCauseTrailingWhitespaceOnOtherwiseEmptyLines :: Assertion
-indentationShouldntCauseTrailingWhitespaceOnOtherwiseEmptyLines
-  = let doc :: Doc ()
-        doc = indent 1 ("x" <> hardline <> hardline <> "y" <> hardline)
-        sdoc = layoutPretty (LayoutOptions Unbounded) doc
-        expected = SChar ' ' (SChar 'x' (SLine 0 (SLine 1 (SChar 'y' (SLine 0 SEmpty)))))
-    in assertEqual "" expected sdoc
-
 computeRibbonWidthWithFloor :: Assertion
 computeRibbonWidthWithFloor
   = let doc :: Doc ()