From bb8091a6ca6d5556e87a2bea6bb46a7b7e5fb32b Mon Sep 17 00:00:00 2001
From: Mikhail Glukhikh <Mikhail.Glukhikh@jetbrains.com>
Date: Wed, 26 Apr 2017 17:12:56 +0300
Subject: [PATCH] KT-17503 add check whether callable reference is acceptable
 in lambda

---
 ...lableReferenceIntoParenthesesInspection.kt | 19 +++++++++++++++++++
 .../expectedFunction.kt                       |  8 ++++++++
 .../LocalInspectionTestGenerated.java         |  6 ++++++
 3 files changed, 33 insertions(+)
 create mode 100644 idea/testData/inspectionsLocal/moveSuspiciousCallableReferenceIntoParentheses/expectedFunction.kt

diff --git a/idea/src/org/jetbrains/kotlin/idea/inspections/MoveSuspiciousCallableReferenceIntoParenthesesInspection.kt b/idea/src/org/jetbrains/kotlin/idea/inspections/MoveSuspiciousCallableReferenceIntoParenthesesInspection.kt
index f184077ce36..b229e01c241 100644
--- a/idea/src/org/jetbrains/kotlin/idea/inspections/MoveSuspiciousCallableReferenceIntoParenthesesInspection.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/inspections/MoveSuspiciousCallableReferenceIntoParenthesesInspection.kt
@@ -21,12 +21,18 @@ import com.intellij.codeInspection.LocalInspectionToolSession
 import com.intellij.codeInspection.ProblemHighlightType
 import com.intellij.codeInspection.ProblemsHolder
 import com.intellij.psi.PsiElementVisitor
+import org.jetbrains.kotlin.builtins.getReturnTypeFromFunctionType
+import org.jetbrains.kotlin.builtins.isBuiltinFunctionalType
+import org.jetbrains.kotlin.builtins.isBuiltinFunctionalTypeOrSubtype
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.intentions.ConvertLambdaToReferenceIntention
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.KtCallableReferenceExpression
 import org.jetbrains.kotlin.psi.KtLambdaExpression
 import org.jetbrains.kotlin.psi.KtVisitorVoid
+import org.jetbrains.kotlin.psi.ValueArgument
+import org.jetbrains.kotlin.resolve.calls.callUtil.getParameterForArgument
+import org.jetbrains.kotlin.resolve.calls.callUtil.getParentResolvedCall
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
 
 class MoveSuspiciousCallableReferenceIntoParenthesesInspection : AbstractKotlinInspection() {
@@ -35,6 +41,19 @@ class MoveSuspiciousCallableReferenceIntoParenthesesInspection : AbstractKotlinI
             override fun visitLambdaExpression(lambdaExpression: KtLambdaExpression) {
                 val callableReference = lambdaExpression.bodyExpression?.statements?.singleOrNull() as? KtCallableReferenceExpression
                 if (callableReference != null) {
+                    val context = lambdaExpression.analyze()
+                    val parentResolvedCall = lambdaExpression.getParentResolvedCall(context)
+                    if (parentResolvedCall != null) {
+                        val originalParameterDescriptor =
+                                parentResolvedCall.getParameterForArgument(lambdaExpression.parent as? ValueArgument)?.original
+                        if (originalParameterDescriptor != null) {
+                            val expectedType = originalParameterDescriptor.type
+                            if (expectedType.isBuiltinFunctionalType) {
+                                val returnType = expectedType.getReturnTypeFromFunctionType()
+                                if (returnType.isBuiltinFunctionalTypeOrSubtype) return
+                            }
+                        }
+                    }
                     holder.registerProblem(
                             lambdaExpression,
                             "Suspicious callable reference as the only lambda element",
diff --git a/idea/testData/inspectionsLocal/moveSuspiciousCallableReferenceIntoParentheses/expectedFunction.kt b/idea/testData/inspectionsLocal/moveSuspiciousCallableReferenceIntoParentheses/expectedFunction.kt
new file mode 100644
index 00000000000..6e6302be35f
--- /dev/null
+++ b/idea/testData/inspectionsLocal/moveSuspiciousCallableReferenceIntoParentheses/expectedFunction.kt
@@ -0,0 +1,8 @@
+// WITH_RUNTIME
+// PROBLEM: none
+
+fun foo(arg: Int) = arg.toString()
+
+fun bar(f: () -> (Int) -> String) {}
+
+val someFun = bar { <caret>::foo }
\ No newline at end of file
diff --git a/idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java b/idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java
index 8f2e62c1fa0..291737a678c 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java
+++ b/idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java
@@ -50,6 +50,12 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             doTest(fileName);
         }
 
+        @TestMetadata("expectedFunction.kt")
+        public void testExpectedFunction() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/moveSuspiciousCallableReferenceIntoParentheses/expectedFunction.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("it.kt")
         public void testIt() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/moveSuspiciousCallableReferenceIntoParentheses/it.kt");