Do the filtering in duplicateImportMsg

Author: philderbeast

cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs

@@ -73,13 +73,19 @@ cyclicalImportMsg path@(ProjectConfigPath (duplicate :| _)) =
     , nest 2 (docProjectConfigPath path)
     ]
 
--- | A message for a duplicate import.
+-- | A message for a duplicate import. If a check for cyclical imports has
+-- already been made then this would report a duplicate import by two different
+-- paths.
 duplicateImportMsg :: FilePath -> ProjectConfigPath -> [(FilePath, ProjectConfigPath)] -> Doc
-duplicateImportMsg duplicate path dupImportsBy =
+duplicateImportMsg duplicate path seenImportsBy =
     vcat
     [ text "duplicate import of" <+> text duplicate <> semi
     , nest 2 (docProjectConfigPath path)
-    , nest 2 (vcat [docProjectConfigPath dib | (_, dib) <- dupImportsBy])
+    , nest 2 $
+        vcat
+        [ docProjectConfigPath dib
+        | (_, dib) <- filter ((duplicate ==) . fst) seenImportsBy
+        ]
     ]
 
 docProjectConfigPathFailReason :: VR -> ProjectConfigPath -> Doc

cabal-install/src/Distribution/Client/ProjectConfig/Legacy.hs

@@ -284,8 +284,7 @@ parseProjectSkeleton cacheDir httpTransport verbosity importsBy projectDir sourc
             | isCyclicConfigPath normLocPath ->
                 pure . parseFail $ ParseUtils.FromString (render $ cyclicalImportMsg normLocPath) Nothing
             | uniqueImport `elem` seenImports -> do
-                let dupImportsBy = filter ((uniqueImport ==) . fst) seenImportsBy
-                pure . parseFail $ ParseUtils.FromString (render $ duplicateImportMsg uniqueImport normLocPath dupImportsBy) Nothing
+                pure . parseFail $ ParseUtils.FromString (render $ duplicateImportMsg uniqueImport normLocPath seenImportsBy) Nothing
             | otherwise -> do
                 normSource <- canonicalizeConfigPath projectDir source
                 let fs = (\z -> CondNode z [normLocPath] mempty) <$> fieldsToConfig normSource (reverse acc)