Respect empty lines after let keyword

source/library/Language/Haskell/Brittany/Internal/S3_ToBriDocTools.hs

@@ -720,6 +720,10 @@ instance DocFlushCommsPost (Maybe GHC.RealSrcSpan) (ToBriDocM BriDocNumbered) wh
       bd <- bdm
       pure (i1, BDFlushCommentsPost (GHC.realSrcSpanEnd loc) shouldMark bd)
 
+instance DocFlushCommsPost GHC.EpaLocation (ToBriDocM BriDocNumbered) where
+  docFlushCommsPost shouldMark epaLocation =
+    docFlushCommsPost shouldMark (Just $ GHC.epaLocationRealSrcSpan epaLocation)
+
 instance DocFlushCommsPost ann (ToBriDocM BriDocNumbered)
       => DocFlushCommsPost ann (ToBriDocM [BriDocNumbered]) where
   docFlushCommsPost shouldMark loc bdm = do

source/library/Language/Haskell/Brittany/Internal/ToBriDoc/Expr.hs

@@ -556,7 +556,10 @@ layoutExpr lexpr@(L _ expr) = do
       -- to making brittany idempotent, even though the result is non-optimal
       -- if "let" is moved horizontally as part of the transformation, as the
       -- comments before the first let item are moved horizontally with it.
-      letDoc  <- shareDoc $ wrapLet $ docLit $ Text.pack "let"
+      letDoc  <- shareDoc
+        $ docFlushCommsPost True spanLet
+        $ wrapLet
+        $ docLitS "let"
       inDoc   <- shareDoc $ wrapIn $ docLit $ Text.pack "in"
       docSetBaseAndIndent $ case fmap snd mBindDocs of
         Just [bindDoc] -> runFilteredAlternative $ do

source/library/Language/Haskell/Brittany/Internal/ToBriDoc/Stmt.hs

@@ -47,18 +47,20 @@ layoutStmt lstmt@(L _ stmt) = do
           ]
         ]
     LetStmt epAnn binds -> docHandleComms epAnn $ do
+      let spanLet = obtainAnnPos epAnn AnnLet
+      letDoc <- shareDoc $ docFlushCommsPost True spanLet $ docLitS "let"
       let isFree = indentPolicy == IndentPolicyFree
       let indentFourPlus = indentAmount >= 4
       (wrapBinds, bindrDocsMay) <- callLayouter layout_localBinds binds
       case bindrDocsMay of
-        Nothing -> docLit $ Text.pack "let"
+        Nothing -> letDoc
           -- i just tested the above, and it is indeed allowed. heh.
-        Just (_, []) -> docLit $ Text.pack "let" -- this probably never happens
+        Just (_, []) -> letDoc -- this probably never happens
         Just (_, [bindDoc]) -> docAlt
           [ -- let bind = expr
             docCols
             ColDoLet
-            [ appSep $ docLit $ Text.pack "let"
+            [ appSep $ letDoc
             , let
                 f = case indentPolicy of
                   IndentPolicyFree -> docSetBaseAndIndent
@@ -71,7 +73,7 @@ layoutStmt lstmt@(L _ stmt) = do
           , -- let
             --   bind = expr
             docAddBaseY BrIndentRegular $ docPar
-            (docLit $ Text.pack "let")
+            letDoc
             (wrapBinds $ docSetBaseAndIndent $ return bindDoc)
           ]
         Just (_, bindDocs) -> runFilteredAlternative $ do
@@ -79,7 +81,7 @@ layoutStmt lstmt@(L _ stmt) = do
           --     bbb = exprb
           --     ccc = exprc
           addAlternativeCond (isFree || indentFourPlus) $ docSeq
-            [ appSep $ docLit $ Text.pack "let"
+            [ appSep $ letDoc
             , let
                 f = if indentFourPlus
                   then docEnsureIndent BrIndentRegular
@@ -93,7 +95,7 @@ layoutStmt lstmt@(L _ stmt) = do
           addAlternativeCond (not indentFourPlus)
             $ docAddBaseY BrIndentRegular
             $ docPar
-                (docLit $ Text.pack "let")
+                letDoc
                 (wrapBinds $ docSetBaseAndIndent $ docLines $ return <$> bindDocs)
     RecStmt epAnn (L _ stmts) _ _ _ _ _ ->
       docHandleComms epAnn $ runFilteredAlternative $ do