std::unordered_set return type by reference vs value [duplicate]

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• C++ Returning reference to local variable 3 answers

Disclaimer: I am new to c++.

I have a code block like this:

  using BucketType = std::unordered_set<Bucket, BucketHash, BucketEqual>;

  const BucketType& Range::buckets(int64_t value) {
    BucketType buckets;
    ...
    return std::move(buckets);
  }

The caller calls this code like this:

  Range range;
  auto buckets = range.buckets(11);

Problem:

When I return the reference of the buckets like the code above, the buckets.size() gives 140732261909672 however, I am only adding 2 buckets in my actual logic. When I change the code to return value instead of reference, it works perfectly fine.

Any pointers on what might be wrong with this code?