Catch GHC errors in listing module names

ghcide/src/Development/IDE/Plugin/Completions.hs

@@ -36,6 +36,7 @@ import Ide.PluginUtils (getClientConfig)
 import Ide.Types
 import TcRnDriver (tcRnImportDecls)
 import Control.Concurrent.Async (concurrently)
+import Data.Bifunctor (second)
 #if defined(GHC_LIB)
 import Development.IDE.Import.DependencyInformation
 #endif
@@ -81,8 +82,7 @@ produceCompletions = do
               case (global, inScope) of
                   ((_, Just globalEnv), (_, Just inScopeEnv)) -> do
                       let uri = fromNormalizedUri $ normalizedFilePathToUri file
-                      cdata <- liftIO $ cacheDataProducer uri env (ms_mod ms) globalEnv inScopeEnv imps parsedDeps
-                      return ([], Just cdata)
+                      second Just <$> liftIO (cacheDataProducer uri env (ms_mod ms) globalEnv inScopeEnv imps parsedDeps)
                   (_diag, _) ->
                       return ([], Nothing)
             _ -> return ([], Nothing)

ghcide/src/Development/IDE/Plugin/Completions/Logic.hs

@@ -59,6 +59,9 @@ import Data.Functor
 import Ide.PluginUtils (mkLspCommand)
 import Ide.Types (CommandId (..), PluginId, WithSnippets (..))
 import Control.Monad
+import Control.Exception (evaluate)
+import Control.DeepSeq (force)
+import Development.IDE.Types.Diagnostics (FileDiagnostic)
 
 -- From haskell-ide-engine/hie-plugin-api/Haskell/Ide/Engine/Context.hs
 
@@ -294,7 +297,7 @@ mkPragmaCompl label insertText =
     Nothing Nothing Nothing Nothing Nothing
 
 
-cacheDataProducer :: Uri -> HscEnv -> Module -> GlobalRdrEnv-> GlobalRdrEnv -> [LImportDecl GhcPs] -> [ParsedModule] -> IO CachedCompletions
+cacheDataProducer :: Uri -> HscEnv -> Module -> GlobalRdrEnv-> GlobalRdrEnv -> [LImportDecl GhcPs] -> [ParsedModule] -> IO ([FileDiagnostic], CachedCompletions)
 cacheDataProducer uri packageState curMod globalEnv inScopeEnv limports deps = do
   let dflags = hsc_dflags packageState
       curModName = moduleName curMod
@@ -309,9 +312,6 @@ cacheDataProducer uri packageState curMod globalEnv inScopeEnv limports deps = d
       -- Full canonical names of imported modules
       importDeclerations = map unLoc limports
 
-      -- The list of all importable Modules from all packages
-      moduleNames = map showModName (listVisibleModuleNames dflags)
-
       -- The given namespaces for the imported modules (ie. full name, or alias if used)
       allModNamesAsNS = map (showModName . asNamespace) importDeclerations
 
@@ -364,14 +364,24 @@ cacheDataProducer uri packageState curMod globalEnv inScopeEnv limports deps = d
         return $ mkNameCompItem uri mbParent originName mn ty Nothing docs imp'
                : recordCompls
 
+  -- The list of all importable Modules from all packages
+  (lvmnDiags, moduleNames) <-
+    catchSrcErrors
+      dflags
+      "listVisibleModuleNames"
+      (evaluate . force $ map showModName (listVisibleModuleNames dflags))
+      <&> \case
+        Left diags -> (diags, [])
+        Right x -> ([], x)
+
   (unquals,quals) <- getCompls rdrElts
 
-  return $ CC
+  return (lvmnDiags, CC
     { allModNamesAsNS = allModNamesAsNS
     , unqualCompls = unquals
     , qualCompls = quals
     , importableModules = moduleNames
-    }
+    })
 
 -- | Produces completions from the top level declarations of a module.
 localCompletionsForParsedModule :: Uri -> ParsedModule -> CachedCompletions