Prefer Data.HashSet.member to Data.Foldable.elem (#2886)

* Prefer Data.HashSet.member to Data.Foldable.elem

* Remove unused binding

Co-authored-by: Pepe Iborra <pepeiborra@gmail.com>

Author: sergv

ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs

@@ -514,7 +514,6 @@ extendImportViaParent df parent child (L l it@ImportDecl{..})
           listAnn = epAnn srcParent [AddEpAnn AnnOpenP (epl 1), AddEpAnn AnnCloseP (epl 0)]
           x :: LIE GhcPs = reLocA $ L l'' $ IEThingWith listAnn parentLIE NoIEWildcard [childLIE]
 
-      let hasSibling = not (null pre)
       lies' <- addCommaInImportList (reverse pre) x
 #endif
       return $ L l it{ideclHiding = Just (hide, L l' lies')}

plugins/hls-rename-plugin/src/Ide/Plugin/Rename.hs

@@ -161,7 +161,7 @@ renameRefs newName refs = everywhere $ mkT replaceLoc
         replace _                = Unqual newName
 
         isRef :: SrcSpan -> Bool
-        isRef = (`elem` refs) . unsafeSrcSpanToLoc
+        isRef = (`HS.member` refs) . unsafeSrcSpanToLoc
 
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