Add dynamic size for AggregationBits

Author: Bez625

spec/electra/attestation.go

@@ -28,9 +28,11 @@ import (
 )
 
 // Attestation is the Ethereum 2 attestation structure.
+//
+//nolint:tagalign
 type Attestation struct {
 	// bitfield.Bitlist has size of n bits + 1 length bit, e.g. an 8 bit list will require a 2 byte array.
-	AggregationBits bitfield.Bitlist `ssz-max:"16385"`
+	AggregationBits bitfield.Bitlist `ssz-max:"16385" dynssz-size:"((MAX_VALIDATORS_PER_COMMITTEE*MAX_COMMITTEES_PER_SLOT)/8 + 1)"`
 	Data            *phase0.AttestationData
 	Signature       phase0.BLSSignature `ssz-size:"96"`
 	// bitfield.Bitvector64 is an 8 byte array so dynamic sizing doesn't make sense.

spec/electra/attestation_ssz.go

@@ -163,6 +163,7 @@ func TestAttestation_SSZ(t *testing.T) {
 
 	// Should only have the bit that was set on the last bit.
 	require.Equal(t, 1, len(aggregateBits.BitIndices()))
+	require.Equal(t, aggregateSize, aggregateBits.Len())
 
 	// Set a bit beyond the bit vector.
 	committeeBits.SetBitAt(committeeSize, true)