From 4b5873bb6850a7096cafd34bab7fcb639face1f4 Mon Sep 17 00:00:00 2001
From: Dirk Faust <d.faust@mittwald.de>
Date: Thu, 14 Sep 2023 07:55:43 +0200
Subject: [PATCH] Add some more cases to lint (PR feedback)

---
 rule/unchecked-type-assertion.go     | 30 +++++++++++++++++
 testdata/unchecked-type-assertion.go | 50 ++++++++++++++++++++++++++--
 2 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/rule/unchecked-type-assertion.go b/rule/unchecked-type-assertion.go
index f5801083b..10b9ff060 100644
--- a/rule/unchecked-type-assertion.go
+++ b/rule/unchecked-type-assertion.go
@@ -96,8 +96,34 @@ func (w *lintUnchekedTypeAssertion) requireNoTypeAssert(expr ast.Expr) {
 	}
 }
 
+func (w *lintUnchekedTypeAssertion) handleIfStmt(n *ast.IfStmt) {
+	ifCondition, ok := n.Cond.(*ast.BinaryExpr)
+	if !ok {
+		return
+	}
+
+	w.requireNoTypeAssert(ifCondition.X)
+	w.requireNoTypeAssert(ifCondition.Y)
+}
+
+func (w *lintUnchekedTypeAssertion) requireBinaryExpressionWithoutTypeAssertion(expr ast.Expr) {
+	binaryExpr, ok := expr.(*ast.BinaryExpr)
+	if ok {
+		w.requireNoTypeAssert(binaryExpr.X)
+		w.requireNoTypeAssert(binaryExpr.Y)
+	}
+}
+
+func (w *lintUnchekedTypeAssertion) handleCaseClause(n *ast.CaseClause) {
+	for _, expr := range n.List {
+		w.requireNoTypeAssert(expr)
+		w.requireBinaryExpressionWithoutTypeAssertion(expr)
+	}
+}
+
 func (w *lintUnchekedTypeAssertion) handleSwitch(n *ast.SwitchStmt) {
 	w.requireNoTypeAssert(n.Tag)
+	w.requireBinaryExpressionWithoutTypeAssertion(n.Tag)
 }
 
 func (w *lintUnchekedTypeAssertion) handleAssignment(n *ast.AssignStmt) {
@@ -144,6 +170,10 @@ func (w *lintUnchekedTypeAssertion) Visit(node ast.Node) ast.Visitor {
 		w.handleReturn(n)
 	case *ast.AssignStmt:
 		w.handleAssignment(n)
+	case *ast.IfStmt:
+		w.handleIfStmt(n)
+	case *ast.CaseClause:
+		w.handleCaseClause(n)
 	}
 
 	return w
diff --git a/testdata/unchecked-type-assertion.go b/testdata/unchecked-type-assertion.go
index b52ed176f..f14b624ed 100644
--- a/testdata/unchecked-type-assertion.go
+++ b/testdata/unchecked-type-assertion.go
@@ -52,7 +52,51 @@ func handleTypeSwitchWithAssignment() {
 	}
 }
 
-func handleTypeSwitchReturn() {
-	// Should not be a lint
-	return foo.(type)
+func handleTypeComparison() {
+	if foo.(int) == 1 { // MATCH /type cast result is unchecked in foo.(int) - type assertion will panic if not matched/
+		return
+	}
+}
+
+func handleTypeComparisonReverse() {
+	if foo.(int) == 1 { // MATCH /type cast result is unchecked in foo.(int) - type assertion will panic if not matched/
+		return
+	}
+}
+
+func handleTypeAssignmentComparison() {
+	var value any
+	value = 42 // int
+
+	if v := value.(int); v == 42 { // MATCH /type cast result is unchecked in value.(int) - type assertion will panic if not matched/
+		fmt.Printf("Value is an integer: %d\n", v)
+	}
+}
+
+func handleSwitchComparison() {
+	switch foo.(int) == 1 { // MATCH /type cast result is unchecked in foo.(int) - type assertion will panic if not matched/
+	case true:
+	case false:
+	}
+}
+
+func handleSwitchComparisonReverse() {
+	switch 1 == foo.(int) { // MATCH /type cast result is unchecked in foo.(int) - type assertion will panic if not matched/
+	case true:
+	case false:
+	}
+}
+
+func handleInnerSwitchAssertion() {
+	switch {
+	case foo.(int) == 1: // MATCH /type cast result is unchecked in foo.(int) - type assertion will panic if not matched/
+	case bar.(int) == 1: // MATCH /type cast result is unchecked in bar.(int) - type assertion will panic if not matched/
+	}
+}
+
+func handleInnerSwitchAssertionReverse() {
+	switch {
+	case 1 == foo.(int): // MATCH /type cast result is unchecked in foo.(int) - type assertion will panic if not matched/
+	case 1 == bar.(int): // MATCH /type cast result is unchecked in bar.(int) - type assertion will panic if not matched/
+	}
 }