When reparsing array indices, do it recursively

src/ShellCheck/Analytics.hs

@@ -2394,6 +2394,7 @@ prop_checkUnused47= verifyNotTree checkUnusedAssignments "a=1; alias hello='echo
 prop_checkUnused48= verifyNotTree checkUnusedAssignments "_a=1"
 prop_checkUnused49= verifyNotTree checkUnusedAssignments "declare -A array; key=a; [[ -v array[$key] ]]"
 prop_checkUnused50= verifyNotTree checkUnusedAssignments "foofunc() { :; }; typeset -fx foofunc"
+prop_checkUnused51= verifyTree checkUnusedAssignments "x[y[z=1]]=1; echo ${x[@]}"
 
 checkUnusedAssignments params t = execWriter (mapM_ warnFor unused)
   where

src/ShellCheck/Parser.hs

@@ -3463,9 +3463,9 @@ notesForContext list = zipWith ($) [first, second] $ filter isName list
 
 -- Go over all T_UnparsedIndex and reparse them as either arithmetic or text
 -- depending on declare -A statements.
-reparseIndices root =
-   analyze blank blank f root
+reparseIndices root = process root
   where
+    process = analyze blank blank f
     associative = getAssociativeArrays root
     isAssociative s = s `elem` associative
     f (T_Assignment id mode name indices value) = do
@@ -3490,8 +3490,9 @@ reparseIndices root =
 
     fixAssignmentIndex name word =
         case word of
-            T_UnparsedIndex id pos src ->
-                parsed name pos src
+            T_UnparsedIndex id pos src -> do
+                idx <- parsed name pos src
+                process idx -- Recursively parse for cases like x[y[z=1]]=1
             _ -> return word
 
     parsed name pos src =