Fix nested type splices in hie fileswip/21619

The issue is that when we compile a typed bracket we replace the splice
with HsSpliced (unTypeCode ...).

Then when computing types for

> [|| T $$(...) ||]

GHC is asked to compute the type of `T $$(..)`, which panics because
of the bogus type of T applied to `HsSpliced`, which is not type
correct.

The fix is to not attempt to compute the type for `HsSpliceE`
constructors if we come across them as they should have either been
already evaluated or lifted into a splice environment.

As part of the patch I made hie files traverse into the splice
environments so now we also get type information for things used inside
nested splices.

Fixes #21619

8 files changed, 83 insertions, 5 deletions

diff --git a/compiler/GHC/Hs/Syn/Type.hs b/compiler/GHC/Hs/Syn/Type.hs
index be1fd40ce0..4b49c41243 100644
--- a/compiler/GHC/Hs/Syn/Type.hs
+++ b/compiler/GHC/Hs/Syn/Type.hs
@@ -133,9 +133,9 @@ hsExprType (HsTypedBracket   (HsBracketTc _ ty _wrap _pending) _) = ty
 hsExprType (HsUntypedBracket (HsBracketTc _ ty _wrap _pending) _) = ty
 hsExprType e@(HsSpliceE{}) = pprPanic "hsExprType: Unexpected HsSpliceE"
                                       (ppr e)
-                                      -- Typed splices should have been eliminated during zonking, but we
-                                      -- can't use `dataConCantHappen` since they are still present before
-                                      -- than in the typechecked AST.
+                               -- Typed splices should have been eliminated during zonking, but we
+                               -- can't use `dataConCantHappen` since they are still present before
+                               -- than in the typechecked AST
 hsExprType (HsProc _ _ lcmd_top) = lhsCmdTopType lcmd_top
 hsExprType (HsStatic (_, ty) _s) = ty
 hsExprType (HsPragE _ _ e) = lhsExprType e
diff --git a/compiler/GHC/Iface/Ext/Ast.hs b/compiler/GHC/Iface/Ext/Ast.hs
index e309fe7d47..86e4522043 100644
--- a/compiler/GHC/Iface/Ext/Ast.hs
+++ b/compiler/GHC/Iface/Ext/Ast.hs
@@ -744,6 +744,9 @@ instance HiePass p => HasType (LocatedA (HsExpr (GhcPass p))) where
         RecordCon con_expr _ _ -> computeType con_expr
         ExprWithTySig _ e _ -> computeLType e
         HsPragE _ _ e -> computeLType e
+        -- By this point all splices are lifted into splice environments so
+        -- the remaining HsSpliceE in the syntax tree contain bogus information.
+        HsSpliceE {} -> Nothing
         XExpr (ExpansionExpr (HsExpanded (HsGetField _ _ _) e)) -> Just (hsExprType e) -- for record-dot-syntax
         XExpr (ExpansionExpr (HsExpanded _ e)) -> computeType e
         XExpr (HsTick _ e) -> computeLType e
@@ -1873,10 +1876,10 @@ instance ToHie (HsQuote a) where
   toHie _ = pure []
 
 instance ToHie PendingRnSplice where
-  toHie _ = pure []
+  toHie (PendingRnSplice _ _ e) = toHie e
 
 instance ToHie PendingTcSplice where
-  toHie _ = pure []
+  toHie (PendingTcSplice _ e) = toHie e
 
 instance ToHie (LBooleanFormula (LocatedN Name)) where
   toHie (L span form) = concatM $ makeNode form (locA span) : case form of
diff --git a/testsuite/tests/hiefile/should_compile/all.T b/testsuite/tests/hiefile/should_compile/all.T
index 73b98a1f94..018585a0f4 100644
--- a/testsuite/tests/hiefile/should_compile/all.T
+++ b/testsuite/tests/hiefile/should_compile/all.T
@@ -16,6 +16,7 @@ test('hie007',       normal,                   compile, ['-fno-code -fwrite-ide-
 test('hie008',       normal,                   compile, ['-fno-code -fwrite-ide-info -fvalidate-ide-info'])
 test('hie009',       normal,                   compile, ['-fno-code -fwrite-ide-info -fvalidate-ide-info'])
 test('hie010',       normal,                   compile, ['-fno-code -fwrite-ide-info -fvalidate-ide-info'])
+test('hie011',       normal,                   compile, ['-fno-code -fwrite-ide-info -fvalidate-ide-info'])
 test('CPP',          normal,                   compile, ['-fno-code -fwrite-ide-info -fvalidate-ide-info'])
 test('Constructors', normal,                   compile, ['-fno-code -fwrite-ide-info -fvalidate-ide-info'])
 test('Scopes',       normal,                   compile, ['-fno-code -fwrite-ide-info -fvalidate-ide-info'])
diff --git a/testsuite/tests/hiefile/should_compile/hie011.hs b/testsuite/tests/hiefile/should_compile/hie011.hs
new file mode 100644
index 0000000000..63a6899fb9
--- /dev/null
+++ b/testsuite/tests/hiefile/should_compile/hie011.hs
@@ -0,0 +1,15 @@
+{-# LANGUAGE TemplateHaskell #-}
+{-# OPTIONS_GHC -fwrite-ide-info #-}
+module M where
+
+import Language.Haskell.TH.Syntax
+
+newtype T = T { getT :: Int }
+
+instance Lift T where
+  lift = undefined
+  liftTyped v = [||T $$(liftTyped (getT v))||]
+
+
+top_level :: ()
+top_level = $$([|| () ||])
diff --git a/testsuite/tests/hiefile/should_compile/hie011.stderr b/testsuite/tests/hiefile/should_compile/hie011.stderr
new file mode 100644
index 0000000000..f31d37d99f
--- /dev/null
+++ b/testsuite/tests/hiefile/should_compile/hie011.stderr
@@ -0,0 +1,2 @@
+Got valid scopes
+Got no roundtrip errors
diff --git a/testsuite/tests/hiefile/should_run/SpliceTypes.hs b/testsuite/tests/hiefile/should_run/SpliceTypes.hs
new file mode 100644
index 0000000000..6ea4134692
--- /dev/null
+++ b/testsuite/tests/hiefile/should_run/SpliceTypes.hs
@@ -0,0 +1,47 @@
+{-# LANGUAGE TemplateHaskell #-}
+
+module Main where
+
+import TestUtils
+import qualified Data.Map as M
+import Data.Foldable
+import Language.Haskell.TH.Syntax
+
+
+newtype T = T { getT :: Int }
+
+instance Lift T where
+  liftTyped v = [||T $$(liftTyped (getT v))||]
+--              ^  ^  ^     ^           ^
+--              1  2  3     4           5
+--
+
+top_level :: ()
+top_level = $$([|| () ||])
+--               ^  ^
+--               1  2
+
+p1,p2, p3, p4:: (Int,Int)
+p1 = (14,18)
+p2 = (14,21)
+p3 = (14,24)
+p4 = (14,29)
+p5 = (14,41)
+
+q1 = (20, 19)
+q2 = (20, 21)
+
+selectPoint' :: HieFile -> (Int,Int) -> HieAST Int
+selectPoint' hf loc =
+  maybe (error "point not found") id $ selectPoint hf loc
+
+main = do
+  (df, hf) <- readTestHie "SpliceTypes.hie"
+  forM_ [p1,p2,p3, p4, p5, q1, q2] $ \point -> do
+    let types = concatMap nodeType $ getSourcedNodeInfo $ sourcedNodeInfo $ selectPoint' hf point
+    case types of
+      [] -> putStrLn $ "No types at " ++ show point
+      _ -> do
+        putStr $ "At " ++ show point ++ ", got type: "
+        forM_ types $ \typ -> do
+          putStrLn (renderHieType df $ recoverFullType typ (hie_types hf))
diff --git a/testsuite/tests/hiefile/should_run/SpliceTypes.stdout b/testsuite/tests/hiefile/should_run/SpliceTypes.stdout
new file mode 100644
index 0000000000..aa2398203a
--- /dev/null
+++ b/testsuite/tests/hiefile/should_run/SpliceTypes.stdout
@@ -0,0 +1,9 @@
+No types at (14,18)
+At (14,21), got type: Int -> T
+No types at (14,24)
+At (14,29), got type: Int -> Code m Int
+forall t (m :: * -> *). (Lift t, Quote m) => t -> Code m t
+forall (m :: * -> *). Quote m => Int -> Code m Int
+At (14,41), got type: T
+No types at (20,19)
+No types at (20,21)
diff --git a/testsuite/tests/hiefile/should_run/all.T b/testsuite/tests/hiefile/should_run/all.T
index 884d58c31f..a4b738d11d 100644
--- a/testsuite/tests/hiefile/should_run/all.T
+++ b/testsuite/tests/hiefile/should_run/all.T
@@ -2,3 +2,4 @@ test('PatTypes', [extra_run_opts('"' + config.libdir + '"')], compile_and_run, [
 test('HieQueries', [extra_run_opts('"' + config.libdir + '"')], compile_and_run, ['-package ghc -fwrite-ide-info'])
 test('T20341', [extra_run_opts('"' + config.libdir + '"')], compile_and_run, ['-package ghc -fwrite-ide-info'])
 test('RecordDotTypes', [extra_run_opts('"' + config.libdir + '"'), extra_files(['TestUtils.hs'])], compile_and_run, ['-package ghc -fwrite-ide-info'])
+test('SpliceTypes', [extra_run_opts('"' + config.libdir + '"'), extra_files(['TestUtils.hs'])], compile_and_run, ['-package ghc -fwrite-ide-info'])