Unnecessary Slice-to-Slice Conversion analyzer (#7321)

* analyzer with tests
* fix bazel file
* modify analyzer to fix build issues
* add analyzer to tool chain
* remove arrays from inspections
* fix redundant [:] operator
* Merge branch 'master' into use-slice-directly
* Merge branch 'master' into use-slice-directly
* fix another inspection
* add package-level comment

BUILD.bazel

@@ -110,6 +110,7 @@ nogo(
         "//tools/analyzers/comparesame:go_tool_library",
         "//tools/analyzers/shadowpredecl:go_tool_library",
         "//tools/analyzers/nop:go_tool_library",
+        "//tools/analyzers/slicedirect:go_tool_library",
     ] + select({
         # nogo checks that fail with coverage enabled.
         ":coverage_enabled": [],

beacon-chain/blockchain/log.go

@@ -30,6 +30,6 @@ func logBlockSyncStatus(block *ethpb.BeaconBlock, blockRoot [32]byte, finalized
 		"block":          fmt.Sprintf("0x%s...", hex.EncodeToString(blockRoot[:])[:8]),
 		"epoch":          helpers.SlotToEpoch(block.Slot),
 		"finalizedEpoch": finalized.Epoch,
-		"finalizedRoot":  fmt.Sprintf("0x%s...", hex.EncodeToString(finalized.Root[:])[:8]),
+		"finalizedRoot":  fmt.Sprintf("0x%s...", hex.EncodeToString(finalized.Root)[:8]),
 	}).Info("Synced new block")
 }

beacon-chain/blockchain/process_block_test.go

@@ -55,7 +55,7 @@ func TestStore_OnBlock(t *testing.T) {
 	require.NoError(t, service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: st.Slot(), Root: randomParentRoot[:]}))
 	require.NoError(t, service.beaconDB.SaveState(ctx, st.Copy(), randomParentRoot))
 	randomParentRoot2 := roots[1]
-	require.NoError(t, service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: st.Slot(), Root: randomParentRoot2[:]}))
+	require.NoError(t, service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: st.Slot(), Root: randomParentRoot2}))
 	require.NoError(t, service.beaconDB.SaveState(ctx, st.Copy(), bytesutil.ToBytes32(randomParentRoot2)))
 
 	tests := []struct {

beacon-chain/core/blocks/attestation_test.go

@@ -238,7 +238,7 @@ func TestProcessAttestations_OK(t *testing.T) {
 		require.NoError(t, err)
 		sigs[i] = sig
 	}
-	att.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+	att.Signature = bls.AggregateSignatures(sigs).Marshal()
 
 	block := testutil.NewBeaconBlock()
 	block.Block.Body.Attestations = []*ethpb.Attestation{att}
@@ -282,7 +282,7 @@ func TestProcessAggregatedAttestation_OverlappingBits(t *testing.T) {
 		require.NoError(t, err)
 		sigs[i] = sig
 	}
-	att1.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+	att1.Signature = bls.AggregateSignatures(sigs).Marshal()
 
 	aggBits2 := bitfield.NewBitlist(4)
 	aggBits2.SetBitAt(1, true)
@@ -305,7 +305,7 @@ func TestProcessAggregatedAttestation_OverlappingBits(t *testing.T) {
 		require.NoError(t, err)
 		sigs[i] = sig
 	}
-	att2.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+	att2.Signature = bls.AggregateSignatures(sigs).Marshal()
 
 	_, err = attaggregation.AggregatePair(att1, att2)
 	assert.ErrorContains(t, aggregation.ErrBitsOverlap.Error(), err)
@@ -347,7 +347,7 @@ func TestProcessAggregatedAttestation_NoOverlappingBits(t *testing.T) {
 		require.NoError(t, err)
 		sigs[i] = sig
 	}
-	att1.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+	att1.Signature = bls.AggregateSignatures(sigs).Marshal()
 
 	aggBits2 := bitfield.NewBitlist(9)
 	aggBits2.SetBitAt(2, true)
@@ -370,7 +370,7 @@ func TestProcessAggregatedAttestation_NoOverlappingBits(t *testing.T) {
 		require.NoError(t, err)
 		sigs[i] = sig
 	}
-	att2.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+	att2.Signature = bls.AggregateSignatures(sigs).Marshal()
 
 	aggregatedAtt, err := attaggregation.AggregatePair(att1, att2)
 	require.NoError(t, err)

beacon-chain/core/blocks/attester_slashing_test.go

@@ -142,7 +142,7 @@ func TestProcessAttesterSlashings_AppliesCorrectStatus(t *testing.T) {
 	sig0 := privKeys[0].Sign(signingRoot[:])
 	sig1 := privKeys[1].Sign(signingRoot[:])
 	aggregateSig := bls.AggregateSignatures([]bls.Signature{sig0, sig1})
-	att1.Signature = aggregateSig.Marshal()[:]
+	att1.Signature = aggregateSig.Marshal()
 
 	att2 := &ethpb.IndexedAttestation{
 		Data: &ethpb.AttestationData{
@@ -157,7 +157,7 @@ func TestProcessAttesterSlashings_AppliesCorrectStatus(t *testing.T) {
 	sig0 = privKeys[0].Sign(signingRoot[:])
 	sig1 = privKeys[1].Sign(signingRoot[:])
 	aggregateSig = bls.AggregateSignatures([]bls.Signature{sig0, sig1})
-	att2.Signature = aggregateSig.Marshal()[:]
+	att2.Signature = aggregateSig.Marshal()
 
 	slashings := []*ethpb.AttesterSlashing{
 		{

beacon-chain/core/blocks/block_regression_test.go

@@ -56,7 +56,7 @@ func TestProcessAttesterSlashings_RegressionSlashableIndices(t *testing.T) {
 		aggSigs = append(aggSigs, sig)
 	}
 	aggregateSig := bls.AggregateSignatures(aggSigs)
-	att1.Signature = aggregateSig.Marshal()[:]
+	att1.Signature = aggregateSig.Marshal()
 
 	root2 := [32]byte{'d', 'o', 'u', 'b', 'l', 'e', '2'}
 	att2 := &ethpb.IndexedAttestation{
@@ -76,7 +76,7 @@ func TestProcessAttesterSlashings_RegressionSlashableIndices(t *testing.T) {
 		aggSigs = append(aggSigs, sig)
 	}
 	aggregateSig = bls.AggregateSignatures(aggSigs)
-	att2.Signature = aggregateSig.Marshal()[:]
+	att2.Signature = aggregateSig.Marshal()
 
 	slashings := []*ethpb.AttesterSlashing{
 		{

beacon-chain/core/blocks/exit_test.go

@@ -174,7 +174,7 @@ func TestProcessVoluntaryExits_AppliesCorrectStatus(t *testing.T) {
 	priv := bls.RandKey()
 	val, err := state.ValidatorAtIndex(0)
 	require.NoError(t, err)
-	val.PublicKey = priv.PublicKey().Marshal()[:]
+	val.PublicKey = priv.PublicKey().Marshal()
 	require.NoError(t, state.UpdateValidatorAtIndex(0, val))
 	exits[0].Signature, err = helpers.ComputeDomainAndSign(state, helpers.CurrentEpoch(state), exits[0].Exit, params.BeaconConfig().DomainVoluntaryExit, priv)
 	require.NoError(t, err)

beacon-chain/core/blocks/randao.go

@@ -39,7 +39,7 @@ func ProcessRandao(
 	if err != nil {
 		return nil, err
 	}
-	if err := verifySignature(buf, proposerPub[:], body.RandaoReveal, domain); err != nil {
+	if err := verifySignature(buf, proposerPub, body.RandaoReveal, domain); err != nil {
 		return nil, errors.Wrap(err, "could not verify block randao")
 	}
 

beacon-chain/core/blocks/signature.go

@@ -70,7 +70,7 @@ func VerifyBlockSignature(beaconState *stateTrie.BeaconState, block *ethpb.Signe
 		return err
 	}
 	proposerPubKey := proposer.PublicKey
-	return helpers.VerifyBlockSigningRoot(block.Block, proposerPubKey[:], block.Signature, domain)
+	return helpers.VerifyBlockSigningRoot(block.Block, proposerPubKey, block.Signature, domain)
 }
 
 // BlockSignatureSet retrieves the block signature set from the provided block and its corresponding state.
@@ -97,7 +97,7 @@ func RandaoSignatureSet(beaconState *stateTrie.BeaconState,
 	if err != nil {
 		return nil, nil, err
 	}
-	set, err := retrieveSignatureSet(buf, proposerPub[:], body.RandaoReveal, domain)
+	set, err := retrieveSignatureSet(buf, proposerPub, body.RandaoReveal, domain)
 	if err != nil {
 		return nil, nil, err
 	}

beacon-chain/core/helpers/attestation_test.go

@@ -89,7 +89,7 @@ func TestAttestation_AggregateSignature(t *testing.T) {
 		for i := 0; i < 100; i++ {
 			priv := bls.RandKey()
 			pub := priv.PublicKey()
-			sig := priv.Sign(msg[:])
+			sig := priv.Sign(msg)
 			pubkeys = append(pubkeys, pub)
 			att := &ethpb.Attestation{Signature: sig.Marshal()}
 			atts = append(atts, att)

beacon-chain/core/state/transition_test.go

@@ -387,7 +387,7 @@ func createFullBlockWithOperations(t *testing.T) (*beaconstate.BeaconState,
 		},
 	}
 	validators := beaconState.Validators()
-	validators[proposerSlashIdx].PublicKey = privKeys[proposerSlashIdx].PublicKey().Marshal()[:]
+	validators[proposerSlashIdx].PublicKey = privKeys[proposerSlashIdx].PublicKey().Marshal()
 	require.NoError(t, beaconState.SetValidators(validators))
 
 	mockRoot2 := [32]byte{'A'}
@@ -407,7 +407,7 @@ func createFullBlockWithOperations(t *testing.T) (*beaconstate.BeaconState,
 	sig0 := privKeys[0].Sign(hashTreeRoot[:])
 	sig1 := privKeys[1].Sign(hashTreeRoot[:])
 	aggregateSig := bls.AggregateSignatures([]bls.Signature{sig0, sig1})
-	att1.Signature = aggregateSig.Marshal()[:]
+	att1.Signature = aggregateSig.Marshal()
 
 	mockRoot3 := [32]byte{'B'}
 	att2 := &ethpb.IndexedAttestation{
@@ -425,7 +425,7 @@ func createFullBlockWithOperations(t *testing.T) (*beaconstate.BeaconState,
 	sig0 = privKeys[0].Sign(hashTreeRoot[:])
 	sig1 = privKeys[1].Sign(hashTreeRoot[:])
 	aggregateSig = bls.AggregateSignatures([]bls.Signature{sig0, sig1})
-	att2.Signature = aggregateSig.Marshal()[:]
+	att2.Signature = aggregateSig.Marshal()
 
 	attesterSlashings := []*ethpb.AttesterSlashing{
 		{
@@ -466,7 +466,7 @@ func createFullBlockWithOperations(t *testing.T) (*beaconstate.BeaconState,
 		sig := privKeys[indice].Sign(hashTreeRoot[:])
 		sigs[i] = sig
 	}
-	blockAtt.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+	blockAtt.Signature = bls.AggregateSignatures(sigs).Marshal()
 
 	exit := &ethpb.SignedVoluntaryExit{
 		Exit: &ethpb.VoluntaryExit{
@@ -784,7 +784,7 @@ func TestProcessBlk_AttsBasedOnValidatorCount(t *testing.T) {
 			sig := privKeys[indice].Sign(hashTreeRoot[:])
 			sigs[i] = sig
 		}
-		att.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+		att.Signature = bls.AggregateSignatures(sigs).Marshal()
 		atts[i] = att
 	}
 

beacon-chain/db/kv/state.go

@@ -194,7 +194,7 @@ func (kv *Store) DeleteStates(ctx context.Context, blockRoots [][32]byte) error
 				continue
 			}
 			// Safe guard against deleting genesis, finalized, head state.
-			if bytes.Equal(blockRoot[:], checkpoint.Root) || bytes.Equal(blockRoot[:], genesisBlockRoot) || bytes.Equal(blockRoot[:], headBlkRoot) {
+			if bytes.Equal(blockRoot, checkpoint.Root) || bytes.Equal(blockRoot, genesisBlockRoot) || bytes.Equal(blockRoot, headBlkRoot) {
 				return errors.New("cannot delete genesis, finalized, or head state")
 			}
 
@@ -203,7 +203,7 @@ func (kv *Store) DeleteStates(ctx context.Context, blockRoots [][32]byte) error
 				return err
 			}
 			indicesByBucket := createStateIndicesFromStateSlot(ctx, slot)
-			if err := deleteValueForIndices(ctx, indicesByBucket, blockRoot[:], tx); err != nil {
+			if err := deleteValueForIndices(ctx, indicesByBucket, blockRoot, tx); err != nil {
 				return errors.Wrap(err, "could not delete root for DB indices")
 			}
 

beacon-chain/p2p/fork_test.go

@@ -245,7 +245,7 @@ func TestDiscv5_AddRetrieveForkEntryENR(t *testing.T) {
 	if !bytes.Equal(resp.CurrentForkDigest, want[:]) {
 		t.Errorf("Wanted fork digest: %v, received %v", want, resp.CurrentForkDigest)
 	}
-	if !bytes.Equal(resp.NextForkVersion[:], nextForkVersion) {
+	if !bytes.Equal(resp.NextForkVersion, nextForkVersion) {
 		t.Errorf("Wanted next fork version: %v, received %v", nextForkVersion, resp.NextForkVersion)
 	}
 	assert.Equal(t, nextForkEpoch, resp.NextForkEpoch, "Unexpected next fork epoch")

beacon-chain/powchain/deposit_test.go

@@ -154,7 +154,7 @@ func TestProcessDeposit_UnableToVerify(t *testing.T) {
 	deposits, keys, err := testutil.DeterministicDepositsAndKeys(1)
 	require.NoError(t, err)
 	sig := keys[0].Sign([]byte{'F', 'A', 'K', 'E'})
-	deposits[0].Data.Signature = sig.Marshal()[:]
+	deposits[0].Data.Signature = sig.Marshal()
 
 	trie, _, err := testutil.DepositTrieFromDeposits(deposits)
 	require.NoError(t, err)

beacon-chain/rpc/validator/aggregator_test.go

@@ -249,7 +249,7 @@ func generateAtt(state *beaconstate.BeaconState, index uint64, privKeys []bls.Se
 		sigs[i] = sig
 	}
 
-	att.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+	att.Signature = bls.AggregateSignatures(sigs).Marshal()
 
 	return att, nil
 }
@@ -290,7 +290,7 @@ func generateUnaggregatedAtt(state *beaconstate.BeaconState, index uint64, privK
 		sigs[i] = sig
 	}
 
-	att.Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+	att.Signature = bls.AggregateSignatures(sigs).Marshal()
 
 	return att, nil
 }

beacon-chain/rpc/validator/attester.go

@@ -110,7 +110,7 @@ func (vs *Server) GetAttestationData(ctx context.Context, req *ethpb.Attestation
 	}
 	targetRoot := make([]byte, 32)
 	if epochStartSlot == headState.Slot() {
-		targetRoot = headRoot[:]
+		targetRoot = headRoot
 	} else {
 		targetRoot, err = helpers.BlockRootAtSlot(headState, epochStartSlot)
 		if err != nil {
@@ -124,7 +124,7 @@ func (vs *Server) GetAttestationData(ctx context.Context, req *ethpb.Attestation
 	res = &ethpb.AttestationData{
 		Slot:            req.Slot,
 		CommitteeIndex:  req.CommitteeIndex,
-		BeaconBlockRoot: headRoot[:],
+		BeaconBlockRoot: headRoot,
 		Source:          headState.CurrentJustifiedCheckpoint(),
 		Target: &ethpb.Checkpoint{
 			Epoch: targetEpoch,

beacon-chain/rpc/validator/proposer.go

@@ -109,7 +109,7 @@ func (vs *Server) GetBlock(ctx context.Context, req *ethpb.BlockRequest) (*ethpb
 
 	blk := &ethpb.BeaconBlock{
 		Slot:          req.Slot,
-		ParentRoot:    parentRoot[:],
+		ParentRoot:    parentRoot,
 		StateRoot:     stateRoot,
 		ProposerIndex: idx,
 		Body: &ethpb.BeaconBlockBody{

beacon-chain/rpc/validator/proposer_test.go

@@ -280,7 +280,7 @@ func TestProposer_ComputeStateRoot_OK(t *testing.T) {
 	proposerIdx, err := helpers.BeaconProposerIndex(beaconState)
 	require.NoError(t, err)
 	require.NoError(t, beaconState.SetSlot(beaconState.Slot()-1))
-	req.Block.Body.RandaoReveal = randaoReveal[:]
+	req.Block.Body.RandaoReveal = randaoReveal
 	currentEpoch := helpers.CurrentEpoch(beaconState)
 	req.Signature, err = helpers.ComputeDomainAndSign(beaconState, currentEpoch, req.Block, params.BeaconConfig().DomainBeaconProposer, privKeys[proposerIdx])
 	require.NoError(t, err)
@@ -1892,7 +1892,7 @@ func TestProposer_FilterAttestation(t *testing.T) {
 						sig := privKeys[indice].Sign(hashTreeRoot[:])
 						sigs[i] = sig
 					}
-					atts[i].Signature = bls.AggregateSignatures(sigs).Marshal()[:]
+					atts[i].Signature = bls.AggregateSignatures(sigs).Marshal()
 				}
 				return atts
 			},

beacon-chain/rpc/validator/server_test.go

@@ -112,8 +112,8 @@ func TestWaitForActivation_ValidatorOriginallyExists(t *testing.T) {
 	priv1 := bls.RandKey()
 	priv2 := bls.RandKey()
 
-	pubKey1 := priv1.PublicKey().Marshal()[:]
-	pubKey2 := priv2.PublicKey().Marshal()[:]
+	pubKey1 := priv1.PublicKey().Marshal()
+	pubKey2 := priv2.PublicKey().Marshal()
 
 	beaconState := &pbp2p.BeaconState{
 		Slot: 4000,
@@ -138,7 +138,7 @@ func TestWaitForActivation_ValidatorOriginallyExists(t *testing.T) {
 	require.NoError(t, err)
 	signingRoot, err := helpers.ComputeSigningRoot(depData, domain)
 	require.NoError(t, err)
-	depData.Signature = priv1.Sign(signingRoot[:]).Marshal()[:]
+	depData.Signature = priv1.Sign(signingRoot[:]).Marshal()
 
 	deposit := &ethpb.Deposit{
 		Data: depData,
@@ -200,9 +200,9 @@ func TestWaitForActivation_MultipleStatuses(t *testing.T) {
 	priv2 := bls.RandKey()
 	priv3 := bls.RandKey()
 
-	pubKey1 := priv1.PublicKey().Marshal()[:]
-	pubKey2 := priv2.PublicKey().Marshal()[:]
-	pubKey3 := priv3.PublicKey().Marshal()[:]
+	pubKey1 := priv1.PublicKey().Marshal()
+	pubKey2 := priv2.PublicKey().Marshal()
+	pubKey3 := priv3.PublicKey().Marshal()
 
 	beaconState := &pbp2p.BeaconState{
 		Slot: 4000,

beacon-chain/state/cloners.go

@@ -120,7 +120,7 @@ func CopyProposerSlashings(slashings []*ethpb.ProposerSlashing) []*ethpb.Propose
 	for i, att := range slashings {
 		newSlashings[i] = CopyProposerSlashing(att)
 	}
-	return newSlashings[:]
+	return newSlashings
 }
 
 // CopyProposerSlashing copies the provided ProposerSlashing.
@@ -156,9 +156,9 @@ func CopyBeaconBlockHeader(header *ethpb.BeaconBlockHeader) *ethpb.BeaconBlockHe
 	return &ethpb.BeaconBlockHeader{
 		Slot:          header.Slot,
 		ProposerIndex: header.ProposerIndex,
-		ParentRoot:    parentRoot[:],
-		StateRoot:     stateRoot[:],
-		BodyRoot:      bodyRoot[:],
+		ParentRoot:    parentRoot,
+		StateRoot:     stateRoot,
+		BodyRoot:      bodyRoot,
 	}
 }
 
@@ -184,10 +184,10 @@ func CopyIndexedAttestation(indexedAtt *ethpb.IndexedAttestation) *ethpb.Indexed
 		return nil
 	} else if indexedAtt.AttestingIndices != nil {
 		indices = make([]uint64, len(indexedAtt.AttestingIndices))
-		copy(indices[:], indexedAtt.AttestingIndices)
+		copy(indices, indexedAtt.AttestingIndices)
 	}
 	return &ethpb.IndexedAttestation{
-		AttestingIndices: indices[:],
+		AttestingIndices: indices,
 		Data:             CopyAttestationData(indexedAtt.Data),
 		Signature:        bytesutil.SafeCopyBytes(indexedAtt.Signature),
 	}
@@ -202,7 +202,7 @@ func CopyAttestations(attestations []*ethpb.Attestation) []*ethpb.Attestation {
 	for i, att := range attestations {
 		newAttestations[i] = CopyAttestation(att)
 	}
-	return newAttestations[:]
+	return newAttestations
 }
 
 // CopyDeposits copies the provided deposit array.
@@ -214,7 +214,7 @@ func CopyDeposits(deposits []*ethpb.Deposit) []*ethpb.Deposit {
 	for i, dep := range deposits {
 		newDeposits[i] = CopyDeposit(dep)
 	}
-	return newDeposits[:]
+	return newDeposits
 }
 
 // CopyDeposit copies the provided deposit.
@@ -250,7 +250,7 @@ func CopySignedVoluntaryExits(exits []*ethpb.SignedVoluntaryExit) []*ethpb.Signe
 	for i, exit := range exits {
 		newExits[i] = CopySignedVoluntaryExit(exit)
 	}
-	return newExits[:]
+	return newExits
 }
 
 // CopySignedVoluntaryExit copies the provided SignedVoluntaryExit.
@@ -274,7 +274,7 @@ func CopyValidator(val *ethpb.Validator) *ethpb.Validator {
 	withdrawalCreds := make([]byte, len(val.WithdrawalCredentials))
 	copy(withdrawalCreds, val.WithdrawalCredentials)
 	return &ethpb.Validator{
-		PublicKey:                  pubKey[:],
+		PublicKey:                  pubKey,
 		WithdrawalCredentials:      withdrawalCreds,
 		EffectiveBalance:           val.EffectiveBalance,
 		Slashed:                    val.Slashed,