"Cascade if" inspection: don't highlight for complex logical conditions

Related to KT-18615

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

@@ -23,6 +23,7 @@ import com.intellij.codeInspection.ProblemsHolder
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.intentions.IfToWhenIntention
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.isIfBranch
 import org.jetbrains.kotlin.idea.intentions.branches
+import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.anyDescendantOfType
 import org.jetbrains.kotlin.psi.psiUtil.lastBlockStatementOrThis
@@ -46,6 +47,20 @@ class CascadeIfInspection : AbstractKotlinInspection() {
                         it is KtBreakExpression || it is KtContinueExpression
                     }) return
 
+                    var current: KtIfExpression? = expression
+                    while (current != null) {
+                        val condition = current.condition
+                        when (condition) {
+                            is KtBinaryExpression -> when (condition.operationToken) {
+                                KtTokens.ANDAND, KtTokens.OROR -> return
+                            }
+                            is KtUnaryExpression -> when (condition.operationToken) {
+                                KtTokens.EXCL -> return
+                            }
+                        }
+                        current = current.`else` as? KtIfExpression
+                    }
+
                     holder.registerProblem(
                             expression.ifKeyword,
                             "Cascade if can be replaced with when",

idea/testData/inspectionsLocal/cascadeIf/complex.kt

@@ -0,0 +1,16 @@
+// PROBLEM: none
+
+fun foo(a: Boolean, b: Boolean, c: Boolean) {
+    <caret>if (a) {
+
+    }
+    else if (b && c) {
+
+    }
+    else if (!c) {
+
+    }
+    else {
+
+    }
+}

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

@@ -59,6 +59,12 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/inspectionsLocal/cascadeIf"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), TargetBackend.ANY, true);
         }
 
+        @TestMetadata("complex.kt")
+        public void testComplex() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/cascadeIf/complex.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("four.kt")
         public void testFour() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/cascadeIf/four.kt");