report 'trait' keyword as deprecated, provide quickfix for replacing with 'interface'

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -142,6 +142,7 @@ public interface Errors {
 
     DiagnosticFactory0<JetDelegatorToSuperClass> SUPERTYPE_NOT_INITIALIZED = DiagnosticFactory0.create(ERROR);
 
+    DiagnosticFactory0<PsiElement> DEPRECATED_TRAIT_KEYWORD = DiagnosticFactory0.create(WARNING);
     DiagnosticFactory0<JetTypeReference> DELEGATION_NOT_TO_TRAIT = DiagnosticFactory0.create(ERROR);
     DiagnosticFactory0<JetTypeReference> SUPERTYPE_NOT_A_CLASS_OR_TRAIT = DiagnosticFactory0.create(ERROR);
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -262,6 +262,7 @@ public class DefaultErrorMessages {
         MAP.put(ENUM_ENTRY_AFTER_ENUM_MEMBER, "Enum entry ''{0}'' is not allowed after a member", NAME);
         MAP.put(DELEGATION_IN_TRAIT, "Interfaces cannot use delegation");
         MAP.put(DELEGATION_NOT_TO_TRAIT, "Only interfaces can be delegated to");
+        MAP.put(DEPRECATED_TRAIT_KEYWORD, "'trait' keyword is deprecated, use 'interface' instead");
         MAP.put(UNMET_TRAIT_REQUIREMENT, "Super interface ''{0}'' requires subclasses to extend ''{1}''", NAME, NAME);
         MAP.put(NO_CONSTRUCTOR, "This class does not have a constructor");
         MAP.put(NOT_A_CLASS, "Not a class");

compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.java

@@ -247,6 +247,11 @@ public class DeclarationsChecker {
         checkTypeParameters(aClass);
 
         if (aClass.isInterface()) {
+            ASTNode traitKeyword = aClass.getNode().findChildByType(JetTokens.TRAIT_KEYWORD);
+            if (traitKeyword != null) {
+                trace.report(Errors.DEPRECATED_TRAIT_KEYWORD.on(traitKeyword.getPsi()));
+            }
+
             checkTraitModifiers(aClass);
             checkConstructorInTrait(aClass);
         }

compiler/testData/diagnostics/tests/DeprecatedTraitKeyword.kt

@@ -0,0 +1,2 @@
+<!DEPRECATED_TRAIT_KEYWORD!>trait<!> A {
+}

compiler/testData/diagnostics/tests/DeprecatedTraitKeyword.txt

@@ -0,0 +1,7 @@
+package
+
+internal interface A {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -181,6 +181,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
             doTest(fileName);
         }
 
+        @TestMetadata("DeprecatedTraitKeyword.kt")
+        public void testDeprecatedTraitKeyword() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/DeprecatedTraitKeyword.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("DiamondFunction.kt")
         public void testDiamondFunction() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/DiamondFunction.kt");

idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/JetPsiChecker.kt

@@ -152,7 +152,8 @@ public open class JetPsiChecker : Annotator, HighlightRangeExtension {
 
                         when (factory) {
                             Errors.DEPRECATED_SYMBOL,
-                            Errors.DEPRECATED_SYMBOL_WITH_MESSAGE
+                            Errors.DEPRECATED_SYMBOL_WITH_MESSAGE,
+                            Errors.DEPRECATED_TRAIT_KEYWORD
                             -> annotation.setTextAttributes(CodeInsightColors.DEPRECATED_ATTRIBUTES)
                         }
 

idea/src/org/jetbrains/kotlin/idea/quickfix/DeprecatedTraitSyntaxFix.kt

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2010-2015 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.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.idea.quickfix
+
+import com.intellij.codeInsight.intention.IntentionAction
+import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.diagnostics.Diagnostic
+import org.jetbrains.kotlin.idea.quickfix.quickfixUtil.createIntentionFactory
+import org.jetbrains.kotlin.lexer.JetTokens
+import org.jetbrains.kotlin.psi.JetClass
+import org.jetbrains.kotlin.psi.JetFile
+import org.jetbrains.kotlin.psi.JetPsiFactory
+
+public class DeprecatedTraitSyntaxFix(element: PsiElement): JetIntentionAction<PsiElement>(element) {
+    override fun getFamilyName() = "Replace with 'interface'"
+    override fun getText() = getFamilyName()
+
+    override fun invoke(project: Project, editor: Editor?, file: JetFile?)
+            = replaceWithInterfaceKeyword(element)
+
+
+    companion object : JetSingleIntentionActionFactory() {
+        fun replaceWithInterfaceKeyword(element: PsiElement) {
+            val cls = JetPsiFactory(element.getProject()).createClass("interface A {}")
+            element.replace(cls.getNode().findChildByType(JetTokens.INTERFACE_KEYWORD)!!.getPsi())
+        }
+
+        override fun createAction(diagnostic: Diagnostic): IntentionAction =
+                DeprecatedTraitSyntaxFix(diagnostic.getPsiElement())
+
+        public fun createWholeProjectFixFactory(): JetSingleIntentionActionFactory = createIntentionFactory {
+            JetWholeProjectForEachElementOfTypeFix.createByPredicate<JetClass>(
+                    predicate = { it.getNode().findChildByType(JetTokens.TRAIT_KEYWORD) != null },
+                    taskProcessor = { replaceWithInterfaceKeyword(it.getNode().findChildByType(JetTokens.TRAIT_KEYWORD).getPsi())},
+                    modalTitle = "Replacing deprecated trait syntax",
+                    name = "Replace with 'interface' in whole project",
+                    familyName = "Replace with 'interface' in whole project"
+            )
+        }
+    }
+}

idea/src/org/jetbrains/kotlin/idea/quickfix/QuickFixRegistrar.java

@@ -105,6 +105,9 @@ public class QuickFixRegistrar {
                                                                                                                         true));
         QuickFixes.factories.put(OPEN_MODIFIER_IN_TRAIT, RemoveModifierFix.createRemoveModifierFromListOwnerFactory(OPEN_KEYWORD, true));
         QuickFixes.factories.put(TRAIT_CAN_NOT_BE_FINAL, removeFinalModifierFactory);
+        QuickFixes.factories.put(DEPRECATED_TRAIT_KEYWORD, DeprecatedTraitSyntaxFix.Companion);
+        QuickFixes.factories.put(DEPRECATED_TRAIT_KEYWORD, DeprecatedTraitSyntaxFix.Companion.createWholeProjectFixFactory());
+
         QuickFixes.factories.put(REDUNDANT_PROJECTION, RemoveModifierFix.createRemoveProjectionFactory(true));
         QuickFixes.factories.put(INCOMPATIBLE_MODIFIERS, RemoveModifierFix.createRemoveModifierFactory(false));
         QuickFixes.factories.put(VARIANCE_ON_TYPE_PARAMETER_OF_FUNCTION_OR_PROPERTY, RemoveModifierFix.createRemoveVarianceFactory());

idea/testData/quickfix/migration/traitToInterface/traitToInterface.kt

@@ -0,0 +1,5 @@
+// "Replace with 'interface'" "true"
+
+<caret>trait Foo {
+
+}

idea/testData/quickfix/migration/traitToInterface/traitToInterface.kt.after

@@ -0,0 +1,5 @@
+// "Replace with 'interface'" "true"
+
+<caret>interface Foo {
+
+}

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixMultiFileTestGenerated.java

@@ -974,6 +974,7 @@ public class QuickFixMultiFileTestGenerated extends AbstractQuickFixMultiFileTes
                 doTestWithExtraFile(fileName);
             }
         }
+
     }
 
     @TestMetadata("idea/testData/quickfix/modifiers")

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixTestGenerated.java

@@ -3277,6 +3277,20 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
             }
         }
 
+        @TestMetadata("idea/testData/quickfix/migration/traitToInterface")
+        @TestDataPath("$PROJECT_ROOT")
+        @RunWith(JUnit3RunnerWithInners.class)
+        public static class TraitToInterface extends AbstractQuickFixTest {
+            public void testAllFilesPresentInTraitToInterface() throws Exception {
+                JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/quickfix/migration/traitToInterface"), Pattern.compile("^(\\w+)\\.kt$"), true);
+            }
+
+            @TestMetadata("traitToInterface.kt")
+            public void testTraitToInterface() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("idea/testData/quickfix/migration/traitToInterface/traitToInterface.kt");
+                doTest(fileName);
+            }
+        }
     }
 
     @TestMetadata("idea/testData/quickfix/modifiers")