Support generating HIE files

Adds a `-fenable-ide-info` flag which instructs GHC to generate `.hie`
files (see the wiki page:
https://ghc.haskell.org/trac/ghc/wiki/HIEFiles).

This is a rebased version of Zubin Duggal's (@wz1000) GHC changes for
his GSOC project, as posted here:
https://gist.github.com/wz1000/5ed4ddd0d3e96d6bc75e095cef95363d.

Test Plan: ./validate

Reviewers: bgamari, gershomb, nomeata, alanz, sjakobi

Reviewed By: alanz, sjakobi

Subscribers: alanz, hvr, sjakobi, rwbarton, wz1000, carter

Differential Revision: https://phabricator.haskell.org/D5239

1 files changed, 143 insertions, 0 deletions

diff --git a/compiler/hieFile/HieDebug.hs b/compiler/hieFile/HieDebug.hs
new file mode 100644
index 0000000000..7896cf7720
--- /dev/null
+++ b/compiler/hieFile/HieDebug.hs
@@ -0,0 +1,143 @@
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleContexts #-}
+module HieDebug where
+
+import GhcPrelude
+
+import SrcLoc
+import Module
+import FastString
+import Outputable
+
+import HieTypes
+import HieBin
+import HieUtils
+
+import qualified Data.Map as M
+import qualified Data.Set as S
+import Data.Function    ( on )
+import Data.List        ( sortOn )
+import Data.Foldable    ( toList )
+
+ppHies :: Outputable a => (HieASTs a) -> SDoc
+ppHies (HieASTs asts) = M.foldrWithKey go "" asts
+  where
+    go k a rest = vcat $
+      [ "File: " <> ppr k
+      , ppHie a
+      , rest
+      ]
+
+ppHie :: Outputable a => HieAST a -> SDoc
+ppHie = go 0
+  where
+    go n (Node inf sp children) = hang header n rest
+      where
+        rest = vcat $ map (go (n+2)) children
+        header = hsep
+          [ "Node"
+          , ppr sp
+          , ppInfo inf
+          ]
+
+ppInfo :: Outputable a => NodeInfo a -> SDoc
+ppInfo ni = hsep
+  [ ppr $ toList $ nodeAnnotations ni
+  , ppr $ nodeType ni
+  , ppr $ M.toList $ nodeIdentifiers ni
+  ]
+
+type Diff a = a -> a -> [SDoc]
+
+diffFile :: Diff HieFile
+diffFile = diffAsts eqDiff `on` (getAsts . hie_asts)
+
+diffAsts :: (Outputable a, Eq a) => Diff a -> Diff (M.Map FastString (HieAST a))
+diffAsts f = diffList (diffAst f) `on` M.elems
+
+diffAst :: (Outputable a, Eq a) => Diff a -> Diff (HieAST a)
+diffAst diffType (Node info1 span1 xs1) (Node info2 span2 xs2) =
+    infoDiff ++ spanDiff ++ diffList (diffAst diffType) xs1 xs2
+  where
+    spanDiff
+      | span1 /= span2 = [hsep ["Spans", ppr span1, "and", ppr span2, "differ"]]
+      | otherwise = []
+    infoDiff
+      = (diffList eqDiff `on` (S.toAscList . nodeAnnotations)) info1 info2
+     ++ (diffList diffType `on` nodeType) info1 info2
+     ++ (diffIdents `on` nodeIdentifiers) info1 info2
+    diffIdents a b = (diffList diffIdent `on` normalizeIdents) a b
+    diffIdent (a,b) (c,d) = diffName a c
+                         ++ eqDiff b d
+    diffName (Right a) (Right b) = case (a,b) of
+      (ExternalName m o _, ExternalName m' o' _) -> eqDiff (m,o) (m',o')
+      (LocalName o _, ExternalName _ o' _) -> eqDiff o o'
+      _ -> eqDiff a b
+    diffName a b = eqDiff a b
+
+type DiffIdent = Either ModuleName HieName
+
+normalizeIdents :: NodeIdentifiers a -> [(DiffIdent,IdentifierDetails a)]
+normalizeIdents = sortOn fst . map (first toHieName) . M.toList
+  where
+    first f (a,b) = (fmap f a, b)
+
+diffList :: Diff a -> Diff [a]
+diffList f xs ys
+  | length xs == length ys = concat $ zipWith f xs ys
+  | otherwise = ["length of lists doesn't match"]
+
+eqDiff :: (Outputable a, Eq a) => Diff a
+eqDiff a b
+  | a == b = []
+  | otherwise = [hsep [ppr a, "and", ppr b, "do not match"]]
+
+validAst :: HieAST a -> Either SDoc ()
+validAst (Node _ span children) = do
+  checkContainment children
+  checkSorted children
+  mapM_ validAst children
+  where
+    checkSorted [] = return ()
+    checkSorted [_] = return ()
+    checkSorted (x:y:xs)
+      | nodeSpan x `leftOf` nodeSpan y = checkSorted (y:xs)
+      | otherwise = Left $ hsep
+          [ ppr $ nodeSpan x
+          , "is not to the left of"
+          , ppr $ nodeSpan y
+          ]
+    checkContainment [] = return ()
+    checkContainment (x:xs)
+      | span `containsSpan` (nodeSpan x) = checkContainment xs
+      | otherwise = Left $ hsep
+          [ ppr $ span
+          , "does not contain"
+          , ppr $ nodeSpan x
+          ]
+
+-- | Look for any identifiers which occur outside of their supposed scopes.
+-- Returns a list of error messages.
+validateScopes :: M.Map FastString (HieAST a) -> [SDoc]
+validateScopes asts = M.foldrWithKey (\k a b -> valid k a ++ b) [] refMap
+  where
+    refMap = generateReferencesMap asts
+    valid (Left _) _ = []
+    valid (Right n) refs = concatMap inScope refs
+      where
+        mapRef = foldMap getScopeFromContext . identInfo . snd
+        scopes = case foldMap mapRef refs of
+          Just xs -> xs
+          Nothing -> []
+        inScope (sp, dets)
+          |  definedInAsts asts n
+          && any isOccurrence (identInfo dets)
+            = case scopes of
+              [] -> []
+              _ -> if any (`scopeContainsSpan` sp) scopes
+                   then []
+                   else return $ hsep $
+                     [ "Name", ppr n, "at position", ppr sp
+                     , "doesn't occur in calculated scope", ppr scopes]
+          | otherwise = []