Fix false positive "Foldable if-then" with Result type

#KT-27074 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/branchedTransformations/IfThenToSafeAccessInspection.kt

@@ -22,13 +22,17 @@ import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiDocumentManager
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.idea.core.replaced
+import org.jetbrains.kotlin.idea.imports.importableFqName
 import org.jetbrains.kotlin.idea.inspections.AbstractApplicabilityBasedInspection
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.*
+import org.jetbrains.kotlin.idea.intentions.callExpression
 import org.jetbrains.kotlin.idea.refactoring.rename.KotlinVariableInplaceRenameHandler
 import org.jetbrains.kotlin.idea.util.application.runWriteAction
+import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
+import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.bindingContextUtil.isUsedAsExpression
 import org.jetbrains.kotlin.resolve.calls.callUtil.getType
 
@@ -55,18 +59,6 @@ class IfThenToSafeAccessInspection : AbstractApplicabilityBasedInspection<KtIfEx
     }
 
     companion object {
-
-        private fun IfThenToSelectData.clausesReplaceableBySafeCall(): Boolean = when {
-            baseClause == null -> false
-            negatedClause == null && baseClause.isUsedAsExpression(context) -> false
-            negatedClause != null && !negatedClause.isNullExpression() -> false
-            baseClause.evaluatesTo(receiverExpression) -> true
-            baseClause.hasFirstReceiverOf(receiverExpression) -> true
-            baseClause.anyArgumentEvaluatesTo(receiverExpression) -> true
-            receiverExpression is KtThisExpression -> getImplicitReceiver()?.let { it.type == receiverExpression.getType(context) } == true
-            else -> false
-        }
-
         fun fixTextFor(element: KtIfExpression): String {
             val ifThenToSelectData = element.buildSelectTransformationData()
             return if (ifThenToSelectData?.baseClauseEvaluatesToReceiver() == true) {
@@ -113,3 +105,33 @@ class IfThenToSafeAccessInspection : AbstractApplicabilityBasedInspection<KtIfEx
         }
     }
 }
+
+private fun IfThenToSelectData.clausesReplaceableBySafeCall(): Boolean = when {
+    baseClause == null -> false
+    negatedClause == null && baseClause.isUsedAsExpression(context) -> false
+    negatedClause != null && !negatedClause.isNullExpression() -> false
+    baseClause.evaluatesTo(receiverExpression) -> true
+    baseClause.hasFirstReceiverOf(receiverExpression) -> withoutResultInCallChain(baseClause, context)
+    baseClause.anyArgumentEvaluatesTo(receiverExpression) -> true
+    receiverExpression is KtThisExpression -> getImplicitReceiver()?.let { it.type == receiverExpression.getType(context) } == true
+    else -> false
+}
+
+private fun withoutResultInCallChain(expression: KtExpression, context: BindingContext): Boolean {
+    if (expression !is KtDotQualifiedExpression || expression.receiverExpression !is KtDotQualifiedExpression) return true
+    return !hasResultInCallExpression(expression, context)
+}
+
+private fun hasResultInCallExpression(expression: KtExpression, context: BindingContext): Boolean =
+    if (expression is KtDotQualifiedExpression)
+        returnTypeIsResult(expression.callExpression, context) || hasResultInCallExpression(expression.receiverExpression, context)
+    else
+        false
+
+private fun returnTypeIsResult(call: KtCallExpression?, context: BindingContext) = call
+    ?.getType(context)
+    ?.constructor
+    ?.declarationDescriptor
+    ?.importableFqName == RESULT_FQNAME
+
+private val RESULT_FQNAME = FqName("kotlin.Result")

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/noStdResultInCallChain.kt

@@ -0,0 +1,11 @@
+// DISABLE-ERRORS
+class Result<T> {
+    fun getOrNull(): Any = TODO()
+}
+val someNullableString: String? = ""
+fun String.bar(): Result<String> = Result.success("")
+val result = if<caret> (someNullableString == null) {
+    null
+} else {
+    someNullableString.bar().getOrNull().let { }
+}

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/noStdResultInCallChain.kt.after

@@ -0,0 +1,7 @@
+// DISABLE-ERRORS
+class Result<T> {
+    fun getOrNull(): Any = TODO()
+}
+val someNullableString: String? = ""
+fun String.bar(): Result<String> = Result.success("")
+val result = someNullableString?.bar()?.getOrNull()?.let { }

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/notApplicableResultInCallChain.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+// WITH_RUNTIME
+// DISABLE-ERRORS
+
+val someNullableString: String? = ""
+fun String.bar(): Result<String> = Result.success("")
+val result = if<caret> (someNullableString == null) {
+    null
+} else {
+    someNullableString.bar().getOrNull().let { }
+}

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/resultCall.kt

@@ -0,0 +1,10 @@
+// DISABLE-ERRORS
+// WITH_RUNTIME
+
+val someNullableString: String? = ""
+fun String.bar(): Result<String> = Result.success("")
+val result = if<caret> (someNullableString == null) {
+    null
+} else {
+    someNullableString.bar()
+}

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/resultCall.kt.after

@@ -0,0 +1,6 @@
+// DISABLE-ERRORS
+// WITH_RUNTIME
+
+val someNullableString: String? = ""
+fun String.bar(): Result<String> = Result.success("")
+val result = someNullableString?.bar()

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

@@ -673,6 +673,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
                 runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/noNullInCondition2.kt");
             }
 
+            @TestMetadata("noStdResultInCallChain.kt")
+            public void testNoStdResultInCallChain() throws Exception {
+                runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/noStdResultInCallChain.kt");
+            }
+
             @TestMetadata("noThenBlock.kt")
             public void testNoThenBlock() throws Exception {
                 runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/noThenBlock.kt");
@@ -688,6 +693,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
                 runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/notApplicableForLocalVar.kt");
             }
 
+            @TestMetadata("notApplicableResultInCallChain.kt")
+            public void testNotApplicableResultInCallChain() throws Exception {
+                runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/notApplicableResultInCallChain.kt");
+            }
+
             @TestMetadata("nullCheckSimple.kt")
             public void testNullCheckSimple() throws Exception {
                 runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/nullCheckSimple.kt");
@@ -728,6 +738,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
                 runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/replaceWithLetInMemberWithIs.kt");
             }
 
+            @TestMetadata("resultCall.kt")
+            public void testResultCall() throws Exception {
+                runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/resultCall.kt");
+            }
+
             @TestMetadata("rhsEqualsNull.kt")
             public void testRhsEqualsNull() throws Exception {
                 runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/rhsEqualsNull.kt");