Fix and clarify breaks from select cases. (#6781)

Update those break statements inside case clauses that are intended to reach an
enclosing for loop, so that they correctly exit the loop.

The candidate files for this change were located using:

    % staticcheck -checks SA4011 ./... | cut -d: -f-2

This change is intended to preserve the intended semantics of the code, but
since the code as-written did not have its intended effect, some behaviour may
change. Specifically: Some loops may have run longer than they were supposed
to, prior to this change.

In one case I was not able to clearly determine the intended outcome. That case
has been commented but otherwise left as-written.

Fixes #6780.

crypto/merkle/proof.go

@@ -204,7 +204,10 @@ func (spn *ProofNode) FlattenAunts() [][]byte {
 		case spn.Right != nil:
 			innerHashes = append(innerHashes, spn.Right.Hash)
 		default:
-			break
+			// FIXME(fromberger): Per the documentation above, exactly one of
+			// these fields should be set. If that is true, this should probably
+			// be a panic since it violates the invariant. If not, when can it
+			// be OK to have no siblings? Does this occur at the leaves?
 		}
 		spn = spn.Parent
 	}

internal/p2p/peermanager.go

@@ -385,7 +385,7 @@ func (m *PeerManager) prunePeers() error {
 		peerID := ranked[i].ID
 		switch {
 		case m.store.Size() <= int(m.options.MaxPeers):
-			break
+			return nil
 		case m.dialing[peerID]:
 		case m.connected[peerID]:
 		default:

state/indexer/block/kv/kv.go

@@ -186,6 +186,7 @@ func (idx *BlockerIndexer) Search(ctx context.Context, q *query.Query) ([]int64,
 
 	// fetch matching heights
 	results = make([]int64, 0, len(filteredHeights))
+heights:
 	for _, hBz := range filteredHeights {
 		h := int64FromBytes(hBz)
 
@@ -199,7 +200,7 @@ func (idx *BlockerIndexer) Search(ctx context.Context, q *query.Query) ([]int64,
 
 		select {
 		case <-ctx.Done():
-			break
+			break heights
 
 		default:
 		}
@@ -240,7 +241,7 @@ func (idx *BlockerIndexer) matchRange(
 	}
 	defer it.Close()
 
-LOOP:
+iter:
 	for ; it.Valid(); it.Next() {
 		var (
 			eventValue string
@@ -260,7 +261,7 @@ LOOP:
 		if _, ok := qr.AnyBound().(int64); ok {
 			v, err := strconv.ParseInt(eventValue, 10, 64)
 			if err != nil {
-				continue LOOP
+				continue iter
 			}
 
 			include := true
@@ -279,7 +280,7 @@ LOOP:
 
 		select {
 		case <-ctx.Done():
-			break
+			break iter
 
 		default:
 		}
@@ -372,12 +373,13 @@ func (idx *BlockerIndexer) match(
 		}
 		defer it.Close()
 
+	iterExists:
 		for ; it.Valid(); it.Next() {
 			tmpHeights[string(it.Value())] = it.Value()
 
 			select {
 			case <-ctx.Done():
-				break
+				break iterExists
 
 			default:
 			}
@@ -399,6 +401,7 @@ func (idx *BlockerIndexer) match(
 		}
 		defer it.Close()
 
+	iterContains:
 		for ; it.Valid(); it.Next() {
 			eventValue, err := parseValueFromEventKey(it.Key())
 			if err != nil {
@@ -411,7 +414,7 @@ func (idx *BlockerIndexer) match(
 
 			select {
 			case <-ctx.Done():
-				break
+				break iterContains
 
 			default:
 			}

state/indexer/tx/kv/kv.go

@@ -219,6 +219,7 @@ func (txi *TxIndex) Search(ctx context.Context, q *query.Query) ([]*abci.TxResul
 	}
 
 	results := make([]*abci.TxResult, 0, len(filteredHashes))
+hashes:
 	for _, h := range filteredHashes {
 		res, err := txi.Get(h)
 		if err != nil {
@@ -229,7 +230,7 @@ func (txi *TxIndex) Search(ctx context.Context, q *query.Query) ([]*abci.TxResul
 		// Potentially exit early.
 		select {
 		case <-ctx.Done():
-			break
+			break hashes
 		default:
 		}
 	}
@@ -285,13 +286,14 @@ func (txi *TxIndex) match(
 		}
 		defer it.Close()
 
+	iterEqual:
 		for ; it.Valid(); it.Next() {
 			tmpHashes[string(it.Value())] = it.Value()
 
 			// Potentially exit early.
 			select {
 			case <-ctx.Done():
-				break
+				break iterEqual
 			default:
 			}
 		}
@@ -308,13 +310,14 @@ func (txi *TxIndex) match(
 		}
 		defer it.Close()
 
+	iterExists:
 		for ; it.Valid(); it.Next() {
 			tmpHashes[string(it.Value())] = it.Value()
 
 			// Potentially exit early.
 			select {
 			case <-ctx.Done():
-				break
+				break iterExists
 			default:
 			}
 		}
@@ -332,6 +335,7 @@ func (txi *TxIndex) match(
 		}
 		defer it.Close()
 
+	iterContains:
 		for ; it.Valid(); it.Next() {
 			value, err := parseValueFromKey(it.Key())
 			if err != nil {
@@ -344,7 +348,7 @@ func (txi *TxIndex) match(
 			// Potentially exit early.
 			select {
 			case <-ctx.Done():
-				break
+				break iterContains
 			default:
 			}
 		}
@@ -412,7 +416,7 @@ func (txi *TxIndex) matchRange(
 	}
 	defer it.Close()
 
-LOOP:
+iter:
 	for ; it.Valid(); it.Next() {
 		value, err := parseValueFromKey(it.Key())
 		if err != nil {
@@ -421,7 +425,7 @@ LOOP:
 		if _, ok := qr.AnyBound().(int64); ok {
 			v, err := strconv.ParseInt(value, 10, 64)
 			if err != nil {
-				continue LOOP
+				continue iter
 			}
 
 			include := true
@@ -448,7 +452,7 @@ LOOP:
 		// Potentially exit early.
 		select {
 		case <-ctx.Done():
-			break
+			break iter
 		default:
 		}
 	}