KtLightMethod: Wrap return type so it resolves to light method's type parameter as opposed to delegate's

Affects java type inference in IDEA

  #KT-12090 Fixed
  #KT-11095 Fixed

compiler/light-classes/src/org/jetbrains/kotlin/asJava/KtLightMethod.kt

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.asJava
 import com.intellij.core.JavaCoreBundle
 import com.intellij.openapi.util.TextRange
 import com.intellij.psi.*
+import com.intellij.psi.impl.compiled.ClsTypeElementImpl
 import com.intellij.psi.impl.light.LightMethod
 import com.intellij.psi.scope.PsiScopeProcessor
 import com.intellij.psi.util.*
@@ -40,6 +41,10 @@ sealed class KtLightMethodImpl(
     override val kotlinOrigin: KtDeclaration? get() = lightMethodOrigin?.originalElement as? KtDeclaration
 
     private val lightIdentifier by lazy(LazyThreadSafetyMode.PUBLICATION) { KtLightIdentifier(this, kotlinOrigin as? KtNamedDeclaration) }
+    private val returnTypeElem by lazy(LazyThreadSafetyMode.PUBLICATION) {
+        val delegateTypeElement = clsDelegate.returnTypeElement as? ClsTypeElementImpl
+        delegateTypeElement?.let { ClsTypeElementImpl(this, it.canonicalText, /*ClsTypeElementImpl.VARIANCE_NONE */ 0.toChar()) }
+    }
 
     override fun getContainingClass(): KtLightClass = super.getContainingClass() as KtLightClass
 
@@ -178,6 +183,12 @@ sealed class KtLightMethodImpl(
         override fun getDefaultValue() = clsDelegate.defaultValue
     }
 
+    // override getReturnType() so return type resolves to type parameters of this method not delegate's
+    // which is relied upon by java type inference
+    override fun getReturnTypeElement(): PsiTypeElement? = returnTypeElem
+
+    override fun getReturnType() = returnTypeElement?.type
+
     companion object Factory {
         fun create(
                 delegate: PsiMethod, origin: LightMemberOrigin?, containingClass: KtLightClass

idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_6.java

@@ -0,0 +1,7 @@
+class InferenceReturnType_1_6 {
+    public static void test(a.C c, a.I i, a.B b) {
+        a.C cc = a.Util.helper(c);
+        a.I ii = a.Util.helper(i);
+        a.B bb = a.Util.helper(b);
+    }
+}

idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_6.kt

@@ -0,0 +1,10 @@
+@file: JvmName("Util")
+
+package a
+
+interface I
+
+class C : I
+class B : I
+
+fun <T : I> T.helper(): T = this

idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_6.txt

@@ -0,0 +1 @@
+// LANGUAGE_LEVEL 1.6

idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_8.java

@@ -0,0 +1,5 @@
+class InferenceReturnType_1_8 {
+    public static void test() {
+        a.A<a.A<String>> ll = a.ValueManager.Companion.reject();
+    }
+}

idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_8.kt

@@ -0,0 +1,11 @@
+@file: JvmName("Util")
+
+package a
+
+class A<T>()
+
+class ValueManager() {
+    companion object {
+        fun <Z> reject() = null as A<Z>
+    }
+}

idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_8.txt

@@ -0,0 +1 @@
+// LANGUAGE_LEVEL 1.8

idea/tests/org/jetbrains/kotlin/checkers/AbstractJavaAgainstKotlinCheckerTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
+ * Copyright 2010-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,8 @@ import com.intellij.codeInspection.nullable.NullableStuffInspection;
 import com.intellij.openapi.module.Module;
 import com.intellij.openapi.projectRoots.Sdk;
 import com.intellij.openapi.util.io.FileUtil;
+import com.intellij.pom.java.LanguageLevel;
+import com.intellij.testFramework.IdeaTestUtil;
 import com.intellij.util.ArrayUtil;
 import com.siyeh.ig.bugs.StaticCallOnSubclassInspection;
 import com.siyeh.ig.bugs.StaticFieldReferenceOnSubclassInspection;
@@ -93,10 +95,25 @@ public abstract class AbstractJavaAgainstKotlinCheckerTest extends KotlinDaemonA
         Module module = super.createMainModule();
 
         String configFileText = getConfigFileText();
-        if (configFileText != null && InTextDirectivesUtils.isDirectiveDefined(configFileText, "// WITH_RUNTIME")) {
+        if (configFileText == null) {
+            return module;
+        }
+
+        if (InTextDirectivesUtils.isDirectiveDefined(configFileText, "// WITH_RUNTIME")) {
             ConfigLibraryUtil.configureKotlinRuntime(module);
         }
 
+        List<String> languageLevelLines = InTextDirectivesUtils.findLinesWithPrefixesRemoved(configFileText, "// LANGUAGE_LEVEL");
+        if (languageLevelLines.size() > 1) {
+            throw new AssertionError("Language level specified multiple times: " + languageLevelLines);
+        }
+        if (languageLevelLines.size() == 1) {
+            LanguageLevel level = LanguageLevel.parse(languageLevelLines.iterator().next());
+            if (level != null) {
+                IdeaTestUtil.setModuleLanguageLevel(module, level);
+            }
+        }
+
         return module;
     }
 

idea/tests/org/jetbrains/kotlin/checkers/JavaAgainstKotlinBinariesCheckerTestGenerated.java

@@ -77,6 +77,18 @@ public class JavaAgainstKotlinBinariesCheckerTestGenerated extends AbstractJavaA
         doTest(fileName);
     }
 
+    @TestMetadata("InferenceReturnType_1_6.kt")
+    public void testInferenceReturnType_1_6() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_6.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("InferenceReturnType_1_8.kt")
+    public void testInferenceReturnType_1_8() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_8.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("InterfaceDefaultImpls.kt")
     public void testInterfaceDefaultImpls() throws Exception {
         String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InterfaceDefaultImpls.kt");

idea/tests/org/jetbrains/kotlin/checkers/JavaAgainstKotlinSourceCheckerTestGenerated.java

@@ -79,6 +79,18 @@ public class JavaAgainstKotlinSourceCheckerTestGenerated extends AbstractJavaAga
             doTest(fileName);
         }
 
+        @TestMetadata("InferenceReturnType_1_6.kt")
+        public void testInferenceReturnType_1_6() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_6.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("InferenceReturnType_1_8.kt")
+        public void testInferenceReturnType_1_8() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InferenceReturnType_1_8.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("InterfaceDefaultImpls.kt")
         public void testInterfaceDefaultImpls() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/kotlinAndJavaChecker/javaAgainstKotlin/InterfaceDefaultImpls.kt");