chore: harden v2 helper edges

Author: zinic

query/v2/query.go

@@ -78,6 +78,7 @@ func ExactDepth(depth int64) TraversalDepth {
 	return newTraversalDepth(depthBound, depthBound)
 }
 
+// Accessors return fresh variables; compare symbols rather than pointer identity.
 func (s runtimeIdentifiers) Path() *cypher.Variable {
 	return cypher.NewVariableWithSymbol(s.path)
 }
@@ -731,6 +732,7 @@ type QueryBuilder interface {
 	Where(constraints ...cypher.SyntaxNode) QueryBuilder
 	OrderBy(sortItems ...any) QueryBuilder
 	Skip(offset int) QueryBuilder
+	// Limit accepts zero, which renders LIMIT 0 and returns an empty result set.
 	Limit(limit int) QueryBuilder
 	Return(projections ...any) QueryBuilder
 	ReturnDistinct(projections ...any) QueryBuilder
@@ -898,6 +900,7 @@ func (s *builder) appendDeleteItems(detach bool, items ...cypher.Expression) {
 		return
 	}
 
+	// Consecutive deletes share one clause; any node delete makes the whole clause DETACH DELETE.
 	lastClauseIdx := len(s.updatingClauses) - 1
 	if lastClauseIdx >= 0 && s.updatingClauses[lastClauseIdx].kind == updatingClauseDelete {
 		s.updatingClauses[lastClauseIdx].detach = s.updatingClauses[lastClauseIdx].detach || detach

query/v2/util.go

@@ -692,12 +692,20 @@ func (s *identifierSet) Clone() *identifierSet {
 }
 
 func (s *identifierSet) Or(other *identifierSet) {
+	if s == nil || other == nil {
+		return
+	}
+
 	for otherIdentifier := range other.identifiers {
 		s.identifiers[otherIdentifier] = struct{}{}
 	}
 }
 
 func (s *identifierSet) Remove(other *identifierSet) {
+	if s == nil || other == nil {
+		return
+	}
+
 	for otherIdentifier := range other.identifiers {
 		delete(s.identifiers, otherIdentifier)
 	}

query/v2/util_internal_test.go

@@ -0,0 +1,20 @@
+package v2
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestIdentifierSetOrAndRemoveNilSafe(t *testing.T) {
+	var nilSet *identifierSet
+
+	nilSet.Or(newIdentifierSet("ignored"))
+	nilSet.Remove(newIdentifierSet("ignored"))
+
+	set := newIdentifierSet("kept")
+	set.Or(nil)
+	set.Remove(nil)
+
+	require.True(t, set.Contains("kept"))
+}