"Remove redundant let" inspection: do not report for long call chains #KT-26289 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/ReplaceSingleLineLetIntention.kt

@@ -21,16 +21,36 @@ import org.jetbrains.kotlin.descriptors.impl.ValueParameterDescriptorImpl
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.core.replaced
 import org.jetbrains.kotlin.idea.inspections.IntentionBasedInspection
+import org.jetbrains.kotlin.idea.intentions.branchedTransformations.lineCount
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.anyDescendantOfType
 import org.jetbrains.kotlin.psi.psiUtil.collectDescendantsOfType
+import org.jetbrains.kotlin.psi.psiUtil.getQualifiedExpressionForSelector
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
 
-class ReplaceSingleLineLetInspection : IntentionBasedInspection<KtCallExpression>(ReplaceSingleLineLetIntention::class) {
+class ReplaceSingleLineLetInspection : IntentionBasedInspection<KtCallExpression>(
+    ReplaceSingleLineLetIntention::class,
+    { element -> isApplicable(element) }
+) {
     override fun inspectionTarget(element: KtCallExpression) = element.calleeExpression
+
+    companion object {
+        fun isApplicable(element: KtCallExpression): Boolean {
+            val qualifiedExpression = element.getQualifiedExpressionForSelector() ?: return true
+            var receiver = qualifiedExpression.receiverExpression as? KtQualifiedExpression ?: return true
+            if (receiver.lineCount() > 1) return false
+            var count = 1
+            while (true) {
+                if (count > 2) return false
+                receiver = receiver.receiverExpression as? KtQualifiedExpression ?: break
+                count++
+            }
+            return true
+        }
+    }
 }
 
 class ReplaceSingleLineLetIntention : SelfTargetingOffsetIndependentIntention<KtCallExpression>(

idea/testData/inspectionsLocal/replaceSingleLineLet/.inspection

@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.intentions.ReplaceSingleLineLetInspection

idea/testData/inspectionsLocal/replaceSingleLineLet/callChain.kt

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>) {
+    list.filter { it > 1 }.filter { it > 2 }.let<caret> { println(it) }
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/callChain.kt.after

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>) {
+    println(list.filter { it > 1 }.filter { it > 2 })
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/callChain2.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>) {
+    list.filter { it > 1 }.filter { it > 2 }
+        .let<caret> { println(it) }
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/callChain2.kt.after

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>) {
+    println(list.filter { it > 1 }.filter { it > 2 })
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/callChain3.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>) {
+    list.filter { it > 1 }.filter { it > 2 }.let<caret> {
+        println(it)
+    }
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/callChain3.kt.after

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(list: List<Int>) {
+    println(list.filter { it > 1 }.filter { it > 2 })
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/callChainWithLineBreak.kt

@@ -0,0 +1,8 @@
+// WITH_RUNTIME
+// PROBLEM: none
+
+fun test(list: List<Int>) {
+    list.filter { it > 1 }
+        .filter { it > 2 }
+        .let<caret> { println(it) }
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/longCallChain.kt

@@ -0,0 +1,6 @@
+// WITH_RUNTIME
+// PROBLEM: none
+
+fun test(list: List<Int>) {
+    list.filter { it > 1 }.filter { it > 2 }.filter { it > 3 }.let<caret> { println(it) }
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/noReceiver.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+
+fun String.test(): Int {
+    return let<caret> {
+        it.length
+    }
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/noReceiver.kt.after

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun String.test(): Int {
+    return length
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/simple.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+
+fun test(s: String?): Int? {
+    return s?.let<caret> {
+        it.length
+    }
+}

idea/testData/inspectionsLocal/replaceSingleLineLet/simple.kt.after

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+
+fun test(s: String?): Int? {
+    return s?.length
+}

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

@@ -5007,6 +5007,54 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
         }
     }
 
+    @TestMetadata("idea/testData/inspectionsLocal/replaceSingleLineLet")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class ReplaceSingleLineLet extends AbstractLocalInspectionTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, TargetBackend.ANY, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInReplaceSingleLineLet() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/inspectionsLocal/replaceSingleLineLet"), Pattern.compile("^([\\w\\-_]+)\\.(kt|kts)$"), TargetBackend.ANY, true);
+        }
+
+        @TestMetadata("callChain.kt")
+        public void testCallChain() throws Exception {
+            runTest("idea/testData/inspectionsLocal/replaceSingleLineLet/callChain.kt");
+        }
+
+        @TestMetadata("callChain2.kt")
+        public void testCallChain2() throws Exception {
+            runTest("idea/testData/inspectionsLocal/replaceSingleLineLet/callChain2.kt");
+        }
+
+        @TestMetadata("callChain3.kt")
+        public void testCallChain3() throws Exception {
+            runTest("idea/testData/inspectionsLocal/replaceSingleLineLet/callChain3.kt");
+        }
+
+        @TestMetadata("callChainWithLineBreak.kt")
+        public void testCallChainWithLineBreak() throws Exception {
+            runTest("idea/testData/inspectionsLocal/replaceSingleLineLet/callChainWithLineBreak.kt");
+        }
+
+        @TestMetadata("longCallChain.kt")
+        public void testLongCallChain() throws Exception {
+            runTest("idea/testData/inspectionsLocal/replaceSingleLineLet/longCallChain.kt");
+        }
+
+        @TestMetadata("noReceiver.kt")
+        public void testNoReceiver() throws Exception {
+            runTest("idea/testData/inspectionsLocal/replaceSingleLineLet/noReceiver.kt");
+        }
+
+        @TestMetadata("simple.kt")
+        public void testSimple() throws Exception {
+            runTest("idea/testData/inspectionsLocal/replaceSingleLineLet/simple.kt");
+        }
+    }
+
     @TestMetadata("idea/testData/inspectionsLocal/replaceStringFormatWithLiteral")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)