IfThenToSafeAccessInspection: fix it works correctly for variable/operator call

#KT-30513 Fixed
#KT-17071 Fixed

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

@@ -104,6 +104,8 @@ private fun IfThenToSelectData.clausesReplaceableBySafeCall(): Boolean = when {
     context.diagnostics.forElement(condition)
         .any { it.factory == Errors.SENSELESS_COMPARISON || it.factory == Errors.USELESS_IS_CHECK } -> false
     baseClause.evaluatesTo(receiverExpression) -> true
+    (baseClause as? KtCallExpression)?.calleeExpression?.evaluatesTo(receiverExpression) == true
+            && baseClause.isCallingInvokeFunction(context) -> true
     baseClause.hasFirstReceiverOf(receiverExpression) -> withoutResultInCallChain(baseClause, context)
     baseClause.anyArgumentEvaluatesTo(receiverExpression) -> true
     receiverExpression is KtThisExpression -> getImplicitReceiver()?.let { it.type == receiverExpression.getType(context) } == true

idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/IfThenUtils.kt

@@ -12,12 +12,15 @@ import com.intellij.openapi.util.TextRange
 import com.intellij.psi.search.LocalSearchScope
 import com.intellij.psi.search.searches.ReferencesSearch
 import org.jetbrains.kotlin.KtNodeTypes
+import org.jetbrains.kotlin.builtins.functions.FunctionInvokeDescriptor
+import org.jetbrains.kotlin.descriptors.SimpleFunctionDescriptor
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.caches.resolve.findModuleDescriptor
 import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToCall
 import org.jetbrains.kotlin.idea.core.KotlinNameSuggester
 import org.jetbrains.kotlin.idea.core.replaced
+import org.jetbrains.kotlin.idea.intentions.callExpression
 import org.jetbrains.kotlin.idea.intentions.getLeftMostReceiverExpression
 import org.jetbrains.kotlin.idea.intentions.replaceFirstReceiver
 import org.jetbrains.kotlin.idea.refactoring.inline.KotlinInlineValHandler
@@ -242,12 +245,36 @@ data class IfThenToSelectData(
                     receiverExpression,
                     baseClause
                 ).insertSafeCalls(factory)
-                baseClause is KtCallExpression -> baseClause.replaceCallWithLet(receiverExpression, factory)
-                else -> baseClause.insertSafeCalls(factory)
+                baseClause is KtCallExpression -> {
+                    val callee = baseClause.calleeExpression
+                    if (callee != null && baseClause.isCallingInvokeFunction(context)) {
+                        factory.createExpressionByPattern("$0?.invoke()", callee)
+                    } else {
+                        baseClause.replaceCallWithLet(receiverExpression, factory)
+                    }
+                }
+                else -> {
+                    var replaced = baseClause.insertSafeCalls(factory)
+                    if (replaced is KtQualifiedExpression) {
+                        val call = replaced.callExpression
+                        val callee = call?.calleeExpression
+                        if (callee != null && call.isCallingInvokeFunction(context)) {
+                            replaced = factory.createExpressionByPattern("$0?.${callee.text}?.invoke()", replaced.receiverExpression)
+                        }
+                    }
+                    replaced
+                }
             }
         }
     }
 
+    internal fun KtExpression.isCallingInvokeFunction(context: BindingContext): Boolean {
+        if (this !is KtCallExpression) return false
+        val resolvedCall = getResolvedCall(context) ?: resolveToCall() ?: return false
+        val descriptor = resolvedCall.resultingDescriptor as? SimpleFunctionDescriptor ?: return false
+        return descriptor is FunctionInvokeDescriptor || descriptor.isOperator && descriptor.name.asString() == "invoke"
+    }
+
     internal fun getImplicitReceiver(): ImplicitReceiver? {
         val resolvedCall = baseClause.getResolvedCall(context) ?: return null
         if (resolvedCall.getExplicitReceiverValue() != null) return null

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

@@ -0,0 +1,8 @@
+// HIGHLIGHT: INFORMATION
+fun test(foo: Foo?) {
+    <caret>if (foo != null) foo()
+}
+
+class Foo {
+    operator fun invoke() {}
+}

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

@@ -0,0 +1,8 @@
+// HIGHLIGHT: INFORMATION
+fun test(foo: Foo?) {
+    foo?.invoke()
+}
+
+class Foo {
+    operator fun invoke() {}
+}

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/callInvokeOperator2.kt

@@ -0,0 +1,11 @@
+class Foo(val bar: Bar)
+
+class Bar {
+    operator fun invoke() {}
+}
+
+fun test(foo: Foo?) {
+    <caret>if (foo != null) {
+        foo.bar()
+    }
+}

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/callInvokeOperator2.kt.after

@@ -0,0 +1,9 @@
+class Foo(val bar: Bar)
+
+class Bar {
+    operator fun invoke() {}
+}
+
+fun test(foo: Foo?) {
+    foo?.bar?.invoke()
+}

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

@@ -0,0 +1,4 @@
+// HIGHLIGHT: INFORMATION
+fun test(foo: (() -> Unit)?) {
+    <caret>if (foo != null) foo()
+}

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

@@ -0,0 +1,4 @@
+// HIGHLIGHT: INFORMATION
+fun test(foo: (() -> Unit)?) {
+    foo?.invoke()
+}

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/callVariable2.kt

@@ -0,0 +1,7 @@
+class Foo(val f: () -> Unit)
+
+fun test(foo: Foo?) {
+    <caret>if (foo != null) {
+        foo.f()
+    }
+}

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/callVariable2.kt.after

@@ -0,0 +1,5 @@
+class Foo(val f: () -> Unit)
+
+fun test(foo: Foo?) {
+    foo?.f?.invoke()
+}

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

@@ -522,6 +522,26 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
                 runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/call4.kt");
             }
 
+            @TestMetadata("callInvokeOperator.kt")
+            public void testCallInvokeOperator() throws Exception {
+                runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/callInvokeOperator.kt");
+            }
+
+            @TestMetadata("callInvokeOperator2.kt")
+            public void testCallInvokeOperator2() throws Exception {
+                runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/callInvokeOperator2.kt");
+            }
+
+            @TestMetadata("callVariable.kt")
+            public void testCallVariable() throws Exception {
+                runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/callVariable.kt");
+            }
+
+            @TestMetadata("callVariable2.kt")
+            public void testCallVariable2() throws Exception {
+                runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/callVariable2.kt");
+            }
+
             @TestMetadata("conditionComparesNullWithNull.kt")
             public void testConditionComparesNullWithNull() throws Exception {
                 runTest("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/conditionComparesNullWithNull.kt");