Fix a false positive when bool modifier is used

docs/changelog.md

@@ -25,15 +25,23 @@
 
 ### Fixed
 
-- Fixed a false positive in [promql/vector_matching](checks/promql/vector_matching.md)
+- Fixed false positive reports in [promql/vector_matching](checks/promql/vector_matching.md)
   for rules using `on(...)`. Example:
 
   ```
   sum(foo) without(instance) * on(app_name) group_left() bar
   ```
 - Don't log passwords when Prometheus URI is using basic authentication.
-- Fixed a false positive reports in [alerts/template](checks/alerts/template.md)
+- Fixed false positive reports in [alerts/template](checks/alerts/template.md)
   suggeting to use `humanize` on queries that already use `round()`.
+- Fixed false positive reports in [alerts/comparison](checks/alerts/comparison.md)
+  when `bool` modifier is used on a condtion that is guarded by another conditon.
+  Example:
+
+  ```yaml
+  alert: Foo
+  expr: (foo > 1) > bool 1
+  ```
 
 ## v0.30.2
 

internal/checks/alerts_comparison.go

@@ -42,8 +42,8 @@ func (c ComparisonCheck) Check(ctx context.Context, rule parser.Rule, entries []
 
 	expr := rule.Expr().Query
 
-	if expr := hasComparision(expr); expr != nil {
-		if expr.ReturnBool {
+	if n := hasComparision(expr.Node); n != nil {
+		if n.ReturnBool && hasComparision(n.LHS) == nil && hasComparision(n.RHS) == nil {
 			problems = append(problems, Problem{
 				Fragment: rule.AlertingRule.Expr.Value.Value,
 				Lines:    rule.AlertingRule.Expr.Lines(),
@@ -70,8 +70,8 @@ func (c ComparisonCheck) Check(ctx context.Context, rule parser.Rule, entries []
 	return
 }
 
-func hasComparision(n *parser.PromQLNode) *promParser.BinaryExpr {
-	if node, ok := n.Node.(*promParser.BinaryExpr); ok {
+func hasComparision(n promParser.Node) *promParser.BinaryExpr {
+	if node, ok := n.(*promParser.BinaryExpr); ok {
 		if node.Op.IsComparisonOperator() {
 			return node
 		}
@@ -80,7 +80,7 @@ func hasComparision(n *parser.PromQLNode) *promParser.BinaryExpr {
 		}
 	}
 
-	for _, child := range n.Children {
+	for _, child := range promParser.Children(n) {
 		if node := hasComparision(child); node != nil {
 			return node
 		}

internal/checks/alerts_comparison_test.go

@@ -151,6 +151,13 @@ func TestComparisonCheck(t *testing.T) {
 			prometheus:  noProm,
 			problems:    noProblems,
 		},
+		{
+			description: "(foo > 1) > bool 1",
+			content:     "- alert: Foo Is Missing\n  expr: (foo > 1) > bool 1\n",
+			checker:     newComparisonCheck,
+			prometheus:  noProm,
+			problems:    noProblems,
+		},
 	}
 
 	runTests(t, testCases)