fix ModLocation for nameless modules

Author: pepeiborra

ghcide/src/Development/IDE/Core/Compile.hs

@@ -731,7 +731,11 @@ getModSummaryFromImports env fp modTime contents = do
     liftIO $ evaluate $ rnf srcImports
     liftIO $ evaluate $ rnf textualImports
 
-    modLoc <- liftIO $ mkHomeModLocation dflags mod fp
+    modLoc <- liftIO $ if mod == mAIN_NAME
+        -- specially in tests it's common to have lots of nameless modules
+        -- mkHomeModLocation will map them to the same hi/hie locations
+        then mkHomeModLocation dflags (pathToModuleName fp) fp
+        else mkHomeModLocation dflags mod fp
 
     let modl = mkHomeModule (hscHomeUnit (hscSetFlags dflags env)) mod
         sourceType = if "-boot" `isSuffixOf` takeExtension fp then HsBootFile else HsSrcFile
@@ -994,3 +998,11 @@ lookupName hsc_env mod name = do
             ATcId{tct_id=id} -> return (AnId id)
             _                -> panic "tcRnLookupName'"
     return res
+
+
+pathToModuleName :: FilePath -> ModuleName
+pathToModuleName = mkModuleName . map rep
+  where
+      rep c | isPathSeparator c = '_'
+      rep ':' = '_'
+      rep c = c