[Fix #237] Look for haskell-debugger-view in ModuleNodes too

Author: Saizan

haskell-debugger/GHC/Debugger/Monad.hs

@@ -26,6 +26,7 @@ import Data.Function
 import Data.Functor.Contravariant
 import Data.IORef
 import Data.Maybe
+import qualified Data.Set as Set
 import Data.Version (makeVersion, showVersion)
 import Prelude hiding (mod)
 #ifdef MIN_VERSION_unix
@@ -599,14 +600,20 @@ findHsDebuggerViewUnitId mod_graph = do
   hsc_env <- getSession
   let unitState = hsc_units hsc_env
 
-  -- Only looks at unit-nodes, this is not robust!
-  -- TODO: Better lookup of unit-id
-  let hskl_dbgr_vws =
+  -- Note: linear in the module graph but only happens once.
+  let potential_units = (`mapMaybe` mg_mss mod_graph) $ \case
+         UnitNode _deps uid -> Just uid
+         ModuleNode _ modl -> Just $ mnkUnitId $ mnKey modl
+         InstantiationNode uid _ -> Just uid
+         LinkNode _ _ -> Nothing
+  -- Note: the intermediate set is expected to be small (<= 2).
+  let hskl_dbgr_vws = Set.toList . Set.fromList $
         [ uid
-        | UnitNode _deps uid <- mg_mss mod_graph
-        , "haskell-debugger-view" `L.isPrefixOf` unitIdString uid
-            || "hskll-dbggr-vw" `L.isPrefixOf` unitIdString uid
-            || "haskell-debug_" `L.isPrefixOf` unitIdString uid
+        | uid <- potential_units
+        , let uid_s = unitIdString uid
+        , "haskell-debugger-view" `L.isPrefixOf` uid_s
+            || "hskll-dbggr-vw" `L.isPrefixOf` uid_s
+            || "haskell-debug_" `L.isPrefixOf` uid_s
         ]
 
       -- If the haskell-debugger-view is in the dependency graph, it must have
@@ -617,7 +624,7 @@ findHsDebuggerViewUnitId mod_graph = do
   case hskl_dbgr_vws of
     [hdv_uid] -> do
       -- In transitive closure, use that one.
-      -- Check that the version is exactly 0.2.0.0
+      -- Check that the version is in supported range.
       case lookupUnit unitState (RealUnit (Definite hdv_uid)) of
         Just unitInfo -> do
           let version = unitPackageVersion unitInfo
@@ -628,8 +635,8 @@ findHsDebuggerViewUnitId mod_graph = do
           error "Could not find unit info for haskell-debugger-view"
     [] -> do
       return Nothing
-    _  ->
-      error "Multiple unit-ids found for haskell-debugger-view in the transitive closure?!"
+    _  -> do
+      error $ "Multiple unit-ids found for haskell-debugger-view in the transitive closure?!" ++ showSDocUnsafe (withPprStyle (PprDump alwaysQualify) (ppr hskl_dbgr_vws))
 
 --------------------------------------------------------------------------------
 -- Utilities