Safe cast with return: fix false negative on lambda last statement #KT-27906 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/SafeCastWithReturnInspection.kt

@@ -30,7 +30,12 @@ class SafeCastWithReturnInspection : AbstractKotlinInspection() {
             if (KtPsiUtil.deparenthesize(parent.right) !is KtReturnExpression) return
 
             val context = expression.analyze(BodyResolveMode.PARTIAL_WITH_DIAGNOSTICS)
-            if (context[BindingContext.USED_AS_EXPRESSION, parent] == true) return
+            if (context[BindingContext.USED_AS_EXPRESSION, parent] == true) {
+                val lambda = expression.getStrictParentOfType<KtLambdaExpression>() ?: return
+                if (lambda.functionLiteral.bodyExpression?.statements?.lastOrNull() != parent) return
+                val call = lambda.getStrictParentOfType<KtCallExpression>() ?: return
+                if (context[BindingContext.USED_AS_EXPRESSION, call] == true) return
+            }
             if (context.diagnostics.forElement(expression.operationReference).any { it.factory == Errors.CAST_NEVER_SUCCEEDS }) return
 
             holder.registerProblem(

idea/testData/inspectionsLocal/safeCastWithReturn/lambdaLastStatement.kt

@@ -0,0 +1,7 @@
+// PROBLEM: none
+// WITH_RUNTIME
+fun test(x: Any) {
+    val s = run {
+        <caret>x as? String ?: return
+    }
+}

idea/testData/inspectionsLocal/safeCastWithReturn/lambdaLastStatement2.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+fun test(x: Any) {
+    run {
+        <caret>x as? String ?: return
+    }
+}

idea/testData/inspectionsLocal/safeCastWithReturn/lambdaLastStatement2.kt.after

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+fun test(x: Any) {
+    run {
+        if (x !is String) return
+    }
+}

idea/testData/inspectionsLocal/safeCastWithReturn/lambdaLastStatement3.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+fun test(x: Any) {
+    run {
+        <caret>x as? String ?: return@run
+    }
+}

idea/testData/inspectionsLocal/safeCastWithReturn/lambdaLastStatement3.kt.after

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+fun test(x: Any) {
+    run {
+        if (x !is String) return@run
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -5593,6 +5593,21 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/safeCastWithReturn/labeledReturn.kt");
         }
 
+        @TestMetadata("lambdaLastStatement.kt")
+        public void testLambdaLastStatement() throws Exception {
+            runTest("idea/testData/inspectionsLocal/safeCastWithReturn/lambdaLastStatement.kt");
+        }
+
+        @TestMetadata("lambdaLastStatement2.kt")
+        public void testLambdaLastStatement2() throws Exception {
+            runTest("idea/testData/inspectionsLocal/safeCastWithReturn/lambdaLastStatement2.kt");
+        }
+
+        @TestMetadata("lambdaLastStatement3.kt")
+        public void testLambdaLastStatement3() throws Exception {
+            runTest("idea/testData/inspectionsLocal/safeCastWithReturn/lambdaLastStatement3.kt");
+        }
+
         @TestMetadata("simple.kt")
         public void testSimple() throws Exception {
             runTest("idea/testData/inspectionsLocal/safeCastWithReturn/simple.kt");