"Cascade if" inspection: do not suggest for one-line if

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

@@ -21,6 +21,7 @@ import com.intellij.codeInspection.LocalInspectionToolSession
 import com.intellij.codeInspection.ProblemHighlightType
 import com.intellij.codeInspection.ProblemsHolder
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.intentions.IfToWhenIntention
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.isOneLiner
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.isIfBranch
 import org.jetbrains.kotlin.idea.intentions.branches
 import org.jetbrains.kotlin.lexer.KtTokens
@@ -36,6 +37,8 @@ class CascadeIfInspection : AbstractKotlinInspection() {
 
                     val branches = expression.branches
                     if (branches.size <= 2) return
+                    if (expression.isOneLiner()) return
+
                     if (branches.any {
                         it == null ||
                         it.lastBlockStatementOrThis() is KtIfExpression

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

@@ -22,7 +22,6 @@ import com.intellij.codeInspection.ProblemHighlightType
 import com.intellij.codeInspection.ProblemHighlightType.GENERIC_ERROR_OR_WARNING
 import com.intellij.codeInspection.ProblemHighlightType.INFORMATION
 import com.intellij.codeInspection.ProblemsHolder
-import com.intellij.openapi.fileEditor.FileDocumentManager
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
@@ -30,6 +29,7 @@ import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.core.canOmitDeclaredType
 import org.jetbrains.kotlin.idea.core.replaced
 import org.jetbrains.kotlin.idea.core.setType
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.isOneLiner
 import org.jetbrains.kotlin.idea.intentions.hasResultingIfWithoutElse
 import org.jetbrains.kotlin.idea.intentions.resultingWhens
 import org.jetbrains.kotlin.idea.util.CommentSaver
@@ -86,12 +86,6 @@ class UseExpressionBodyInspection(private val convertEmptyToUnit: Boolean) : Abs
                 }
             }
 
-    private fun KtExpression.isOneLiner(): Boolean {
-        val file = containingFile?.virtualFile ?: return false
-        val document = FileDocumentManager.getInstance().getDocument(file) ?: return false
-        return document.getLineNumber(textRange.startOffset) == document.getLineNumber(textRange.endOffset)
-    }
-
     private fun KtDeclarationWithBody.findValueStatement(): KtExpression? {
         val body = blockExpression() ?: return null
         return body.findValueStatement()

idea/testData/inspectionsLocal/cascadeIf/oneLiner.kt

@@ -0,0 +1,5 @@
+// PROBLEM: none
+
+fun foo(a: Boolean, b: Boolean): Int {
+    return <caret>if (a) 42 else if (b) 13 else 0
+}

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

@@ -101,6 +101,12 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("oneLiner.kt")
+        public void testOneLiner() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/cascadeIf/oneLiner.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("shortIf.kt")
         public void testShortIf() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/cascadeIf/shortIf.kt");