In (( x = y )), logic to not reference x also grabbed y

ShellCheck/Analytics.hs

@@ -2071,6 +2071,7 @@ prop_checkUnused30= verifyTree checkUnusedAssignments "let a=1"
 prop_checkUnused31= verifyTree checkUnusedAssignments "let 'a=1'"
 prop_checkUnused32= verifyTree checkUnusedAssignments "let a=b=c; echo $a"
 prop_checkUnused33= verifyNotTree checkUnusedAssignments "a=foo; [[ foo =~ ^{$a}$ ]]"
+prop_checkUnused34= verifyNotTree checkUnusedAssignments "foo=1; (( t = foo )); echo $t"
 checkUnusedAssignments params t = execWriter (mapM_ warnFor unused)
   where
     flow = variableFlow params

ShellCheck/AnalyzerLib.hs

@@ -520,7 +520,7 @@ getReferencedVariables parents t =
     isDereferencing = (`elem` ["-eq", "-ne", "-lt", "-le", "-gt", "-ge"])
 
     isArithmeticAssignment t = case getPath parents t of
-        this: TA_Assignment _ "=" _ _ :_ -> True
+        this: TA_Assignment _ "=" lhs _ :_ -> lhs == t
         _ -> False
 
 dataTypeFrom defaultType v = (case v of T_Array {} -> DataArray; _ -> defaultType) $ SourceFrom [v]