From 8916b91907833b5aaabd493d4184444383fa0ba5 Mon Sep 17 00:00:00 2001
From: Simon Jakobi <simon.jakobi@gmail.com>
Date: Fri, 8 Nov 2019 05:24:38 +0100
Subject: [PATCH 1/2] Add regression test for #91

---
 prettyprinter/test/Testsuite/Main.hs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/prettyprinter/test/Testsuite/Main.hs b/prettyprinter/test/Testsuite/Main.hs
index 97695e0f..d03e2784 100644
--- a/prettyprinter/test/Testsuite/Main.hs
+++ b/prettyprinter/test/Testsuite/Main.hs
@@ -80,6 +80,8 @@ tests = testGroup "Tests"
             , testCase "Preserve leading indentation"
                        removeTrailingWhitespacePreserveIndentation
             ]
+        , testCase "Unbounded layout of `group`ed Line fails (#91)"
+                   regressionUnboundedGroupedLine
         ]
     ]
 
@@ -296,3 +298,9 @@ removeTrailingWhitespacePreserveIndentation
   = let sdoc :: SimpleDocStream ()
         sdoc = SLine 2 (SChar 'x' SEmpty)
     in assertEqual "" sdoc (removeTrailingWhitespace sdoc)
+
+regressionUnboundedGroupedLine :: Assertion
+regressionUnboundedGroupedLine
+  = let sdoc :: SimpleDocStream ()
+        sdoc = layoutPretty (LayoutOptions Unbounded) (group hardline)
+    in assertEqual "" (SLine 0 SEmpty) sdoc

From a06e0cd97f7da39458553912567965c8f82e93fe Mon Sep 17 00:00:00 2001
From: Simon Jakobi <simon.jakobi@gmail.com>
Date: Fri, 8 Nov 2019 04:25:02 +0100
Subject: [PATCH 2/2] Fix #91 by removing the shortcuts from the fitting
 predicates

---
 .../src/Data/Text/Prettyprint/Doc/Internal.hs | 37 ++++++++-----------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/prettyprinter/src/Data/Text/Prettyprint/Doc/Internal.hs b/prettyprinter/src/Data/Text/Prettyprint/Doc/Internal.hs
index 9c966c25..9ee709a2 100755
--- a/prettyprinter/src/Data/Text/Prettyprint/Doc/Internal.hs
+++ b/prettyprinter/src/Data/Text/Prettyprint/Doc/Internal.hs
@@ -1654,21 +1654,19 @@ layoutPretty
     -> Doc ann
     -> SimpleDocStream ann
 layoutPretty = layoutWadlerLeijen
-    (FittingPredicate (\_pWidth _minNestingLevel maxWidth sdoc -> case maxWidth of
-        Nothing -> True
-        Just w -> fits w sdoc ))
+    (FittingPredicate (\_pWidth _minNestingLevel maxWidth sdoc -> fits maxWidth sdoc))
   where
-    fits :: Int -- ^ Width in which to fit the first line
+    fits :: Maybe Int -- ^ Width in which to fit the first line
          -> SimpleDocStream ann
          -> Bool
-    fits w _ | w < 0      = False
-    fits _ SFail          = False
-    fits _ SEmpty         = True
-    fits w (SChar _ x)    = fits (w - 1) x
-    fits w (SText l _t x) = fits (w - l) x
-    fits _ SLine{}        = True
-    fits w (SAnnPush _ x) = fits w x
-    fits w (SAnnPop x)    = fits w x
+    fits (Just w) _ | w < 0 = False
+    fits _ SFail            = False
+    fits _ SEmpty           = True
+    fits w (SChar _ x)      = fits (pred <$> w) x
+    fits w (SText l _t x)   = fits (subtract l <$> w) x
+    fits _ SLine{}          = True
+    fits w (SAnnPush _ x)   = fits w x
+    fits w (SAnnPop x)      = fits w x
 
 -- | A layout algorithm with more lookahead than 'layoutPretty', that introduces
 -- line breaks earlier if the content does not (or will not, rather) fit into
@@ -1719,10 +1717,7 @@ layoutSmart
     :: LayoutOptions
     -> Doc ann
     -> SimpleDocStream ann
-layoutSmart = layoutWadlerLeijen
-    (FittingPredicate (\pWidth minNestingLevel maxWidth sdoc -> case maxWidth of
-        Nothing -> True
-        Just w -> fits pWidth minNestingLevel w sdoc ))
+layoutSmart = layoutWadlerLeijen (FittingPredicate fits)
   where
     -- Search with more lookahead: assuming that nesting roughly corresponds to
     -- syntactic depth, @fits@ checks that not only the current line fits, but
@@ -1733,16 +1728,16 @@ layoutSmart = layoutWadlerLeijen
     -- exponential runtime (and is prohibitively expensive in practice).
     fits :: PageWidth
          -> Int -- ^ Minimum nesting level to fit in
-         -> Int -- ^ Width in which to fit the first line
+         -> Maybe Int -- ^ Width in which to fit the first line
          -> SimpleDocStream ann
          -> Bool
-    fits _ _ w _ | w < 0                    = False
+    fits _ _ (Just w) _ | w < 0             = False
     fits _ _ _ SFail                        = False
     fits _ _ _ SEmpty                       = True
-    fits pw m w (SChar _ x)                 = fits pw m (w - 1) x
-    fits pw m w (SText l _t x)              = fits pw m (w - l) x
+    fits pw m w (SChar _ x)                 = fits pw m (pred <$> w) x
+    fits pw m w (SText l _t x)              = fits pw m (subtract l <$> w) x
     fits pw m _ (SLine i x)
-      | m < i, AvailablePerLine cpl _ <- pw = fits pw m (cpl - i) x
+      | m < i, AvailablePerLine cpl _ <- pw = fits pw m (Just (cpl - i)) x
       | otherwise                           = True
     fits pw m w (SAnnPush _ x)              = fits pw m w x
     fits pw m w (SAnnPop x)                 = fits pw m w x