val / var are now forbidden on a loop multi declaration parameter #KT-6274 Fixed

VAL_OR_VAR_ON_LOOP_MULTI_PARAMETER error added
KtValVarKeywordOwner interface added for PSIs that have getValOrVarKeyword method

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

@@ -667,6 +667,7 @@ public interface Errors {
     DiagnosticFactory3<KtExpression, DeclarationDescriptor, Visibility, DeclarationDescriptor> INVISIBLE_SETTER = DiagnosticFactory3.create(ERROR);
 
     DiagnosticFactory1<PsiElement, KtKeywordToken> VAL_OR_VAR_ON_LOOP_PARAMETER = DiagnosticFactory1.create(ERROR);
+    DiagnosticFactory1<PsiElement, KtKeywordToken> VAL_OR_VAR_ON_LOOP_MULTI_PARAMETER = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<PsiElement, KtKeywordToken> VAL_OR_VAR_ON_FUN_PARAMETER = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<PsiElement, KtKeywordToken> VAL_OR_VAR_ON_CATCH_PARAMETER = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<PsiElement, KtKeywordToken> VAL_OR_VAR_ON_SECONDARY_CONSTRUCTOR_PARAMETER = DiagnosticFactory1.create(ERROR);

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

@@ -264,6 +264,7 @@ public class DefaultErrorMessages {
         MAP.put(VARIABLE_EXPECTED, "Variable expected");
 
         MAP.put(VAL_OR_VAR_ON_LOOP_PARAMETER, "''{0}'' on loop parameter is not allowed", TO_STRING);
+        MAP.put(VAL_OR_VAR_ON_LOOP_MULTI_PARAMETER, "''{0}'' on loop multi parameter is not allowed", TO_STRING);
         MAP.put(VAL_OR_VAR_ON_FUN_PARAMETER, "''{0}'' on function parameter is not allowed", TO_STRING);
         MAP.put(VAL_OR_VAR_ON_CATCH_PARAMETER, "''{0}'' on catch parameter is not allowed", TO_STRING);
         MAP.put(VAL_OR_VAR_ON_SECONDARY_CONSTRUCTOR_PARAMETER, "''{0}'' on secondary constructor parameter is not allowed", TO_STRING);

compiler/frontend/src/org/jetbrains/kotlin/psi/KtMultiDeclaration.java

@@ -29,7 +29,7 @@ import java.util.List;
 
 import static org.jetbrains.kotlin.lexer.KtTokens.*;
 
-public class KtMultiDeclaration extends KtDeclarationImpl {
+public class KtMultiDeclaration extends KtDeclarationImpl implements KtValVarKeywordOwner {
     public KtMultiDeclaration(@NotNull ASTNode node) {
         super(node);
     }

compiler/frontend/src/org/jetbrains/kotlin/psi/KtParameter.java

@@ -31,7 +31,7 @@ import org.jetbrains.kotlin.psi.typeRefHelpers.TypeRefHelpersKt;
 import java.util.Collections;
 import java.util.List;
 
-public class KtParameter extends KtNamedDeclarationStub<KotlinParameterStub> implements KtCallableDeclaration {
+public class KtParameter extends KtNamedDeclarationStub<KotlinParameterStub> implements KtCallableDeclaration, KtValVarKeywordOwner {
 
     public KtParameter(@NotNull ASTNode node) {
         super(node);

compiler/frontend/src/org/jetbrains/kotlin/psi/KtValVarKeywordOwner.java

@@ -0,0 +1,25 @@
+/*
+ * 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.psi;
+
+import com.intellij.psi.PsiElement;
+import org.jetbrains.annotations.Nullable;
+
+public interface KtValVarKeywordOwner extends PsiElement {
+    @Nullable
+    PsiElement getValOrVarKeyword();
+}

compiler/frontend/src/org/jetbrains/kotlin/psi/KtVariableDeclaration.java

@@ -16,12 +16,6 @@
 
 package org.jetbrains.kotlin.psi;
 
-import com.intellij.psi.PsiElement;
-import org.jetbrains.annotations.Nullable;
-
-public interface KtVariableDeclaration extends KtCallableDeclaration, KtWithExpressionInitializer {
+public interface KtVariableDeclaration extends KtCallableDeclaration, KtWithExpressionInitializer, KtValVarKeywordOwner {
     boolean isVar();
-
-    @Nullable
-    PsiElement getValOrVarKeyword();
 }

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

@@ -163,7 +163,7 @@ public class ModifiersChecker {
         }
 
         public void checkParameterHasNoValOrVar(
-                @NotNull KtParameter parameter,
+                @NotNull KtValVarKeywordOwner parameter,
                 @NotNull DiagnosticFactory1<PsiElement, KtKeywordToken> diagnosticFactory
         ) {
             PsiElement valOrVar = parameter.getValOrVarKeyword();

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/ControlStructureTypingVisitor.java

@@ -407,6 +407,7 @@ public class ControlStructureTypingVisitor extends ExpressionTypingVisitor {
                         loopScope, multiParameter, iteratorNextAsReceiver, loopRange, context
                 );
                 components.modifiersChecker.withTrace(context.trace).checkModifiersForMultiDeclaration(multiParameter);
+                components.modifiersChecker.withTrace(context.trace).checkParameterHasNoValOrVar(multiParameter, VAL_OR_VAR_ON_LOOP_MULTI_PARAMETER);
                 components.identifierChecker.checkDeclaration(multiParameter, context.trace);
             }
         }

compiler/testData/diagnostics/tests/controlStructures/valVarLoopParameter.kt

@@ -1,3 +1,18 @@
+class Pair {
+    operator fun component1(): Int = null!!
+    operator fun component2(): Int = null!!
+}
+
+class Coll {
+    operator fun iterator(): It = It()
+}
+
+class It {
+    operator fun next() = Pair()
+    operator fun hasNext() = false
+}
+
+
 fun f() {
     for (<!VAL_OR_VAR_ON_LOOP_PARAMETER!>val<!> i in 1..4) {
 
@@ -6,4 +21,12 @@ fun f() {
     for (<!VAL_OR_VAR_ON_LOOP_PARAMETER!>var<!> i in 1..4) {
 
     }
+
+    for (<!VAL_OR_VAR_ON_LOOP_MULTI_PARAMETER!>val<!> (i,j) in Coll()) {
+
+    }
+
+    for (<!VAL_OR_VAR_ON_LOOP_MULTI_PARAMETER!>var<!> (i,j) in Coll()) {
+
+    }
 }

compiler/testData/diagnostics/tests/controlStructures/valVarLoopParameter.txt

@@ -1,3 +1,29 @@
 package
 
 public fun f(): kotlin.Unit
+
+public final class Coll {
+    public constructor Coll()
+    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 final operator fun iterator(): It
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class It {
+    public constructor It()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final operator fun hasNext(): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun next(): Pair
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Pair {
+    public constructor Pair()
+    public final operator fun component1(): kotlin.Int
+    public final operator fun component2(): kotlin.Int
+    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/testData/diagnostics/tests/declarationChecks/DataFlowInMultiDeclInFor.kt

@@ -8,7 +8,7 @@ class A {
 }
 
 fun foo(list: List<A>) {
-    for (var (c1, c2, c3) in list) {
+    for (<!VAL_OR_VAR_ON_LOOP_MULTI_PARAMETER!>var<!> (c1, c2, c3) in list) {
         <!UNUSED_VALUE!>c1 =<!> 1
         c3 + 1
     }