Repository: intellij-rust/intellij-rust
Issue: Exception when trying to rename tuple field

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## Environment

* **Intellij-Rust plugin version:** v0.2.93.2117-183
* **Rust toolchain version:** 1.34.0-nightly
* **IDE name and version:** Idea Community 2018.3.5
* **Operating system:** Manjaro Linux

## Problem description
Exception when trying to rename tuple field. Rename shouldn't be available for tuple fields.
<details>
  <summary>stack trace</summary>

```
java.lang.Throwable: Unknown element type:RsTupleFieldDeclImpl(TUPLE_FIELD_DECL)
	at com.intellij.openapi.diagnostic.Logger.error(Logger.java:134)
	at com.intellij.refactoring.rename.RenameUtil.doRenameGenericNamedElement(RenameUtil.java:218)
	at com.intellij.refactoring.rename.RenamePsiElementProcessor.renameElement(RenamePsiElementProcessor.java:48)
	at com.intellij.refactoring.rename.RenameUtil.doRename(RenameUtil.java:188)
	at com.intellij.refactoring.rename.RenameProcessor.performRefactoring(RenameProcessor.java:358)
	at com.intellij.refactoring.BaseRefactoringProcessor.lambda$doRefactoring$9(BaseRefactoringProcessor.java:460)
	at com.intellij.refactoring.BaseRefactoringProcessor.lambda$doRefactoring$10(BaseRefactoringProcessor.java:471)
	at com.intellij.openapi.application.impl.ApplicationImpl.lambda$null$15(ApplicationImpl.java:1015)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:164)
	at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:582)
	at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:532)
	at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:87)
	at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:151)
	at com.intellij.openapi.progress.util.PotemkinProgress.runInSwingThread(PotemkinProgress.java:183)
	at com.intellij.openapi.application.impl.ApplicationImpl.lambda$runEdtProgressWriteAction$16(ApplicationImpl.java:1015)
	at com.intellij.openapi.application.impl.ApplicationImpl.runWriteActionWithClass(ApplicationImpl.java:1023)
	at com.intellij.openapi.application.impl.ApplicationImpl.runEdtProgressWriteAction(ApplicationImpl.java:1013)
	at com.intellij.openapi.application.impl.ApplicationImpl.runWriteActionWithNonCancellableProgressInDispatchThread(ApplicationImpl.java:997)
	at com.intellij.refactoring.BaseRefactoringProcessor.doRefactoring(BaseRefactoringProcessor.java:471)
	at com.intellij.refactoring.BaseRefactoringProcessor.lambda$execute$2(BaseRefactoringProcessor.java:299)
	at com.intellij.openapi.command.impl.CoreCommandProcessor.executeCommand(CoreCommandProcessor.java:220)
	at com.intellij.openapi.command.impl.CoreCommandProcessor.executeCommand(CoreCommandProcessor.java:178)
	at com.intellij.openapi.command.impl.CoreCommandProcessor.executeCommand(CoreCommandProcessor.java:168)
	at com.intellij.refactoring.BaseRefactoringProcessor.execute(BaseRefactoringProcessor.java:297)
	at com.intellij.refactoring.BaseRefactoringProcessor.doRun(BaseRefactoringProcessor.java:228)
	at com.intellij.refactoring.rename.RenameProcessor.doRun(RenameProcessor.java:104)
	at com.intellij.refactoring.BaseRefactoringProcessor.run(BaseRefactoringProcessor.java:547)
	at com.intellij.refactoring.ui.RefactoringDialog.invokeRefactoring(RefactoringDialog.java:191)
	at com.intellij.refactoring.rename.RenameDialog.performRename(RenameDialog.java:301)
	at com.intellij.refactoring.rename.RenameDialog.doAction(RenameDialog.java:279)
	at com.intellij.refactoring.ui.RefactoringDialog.doRefactorAction(RefactoringDialog.java:86)
	at com.intellij.refactoring.ui.RefactoringDialog$RefactorAction.actionPerformed(RefactoringDialog.java:169)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
	at java.awt.Component.processMouseEvent(Component.java:6548)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3325)
	at java.awt.Component.processEvent(Component.java:6313)
	at java.awt.Container.processEvent(Container.java:2237)
	at java.awt.Component.dispatchEventImpl(Component.java:4903)
	at java.awt.Container.dispatchEventImpl(Container.java:2295)
	at java.awt.Component.dispatchEvent(Component.java:4725)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4889)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4526)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4467)
	at java.awt.Container.dispatchEventImpl(Container.java:2281)
	at java.awt.Window.dispatchEventImpl(Window.java:2746)
	at java.awt.Component.dispatchEvent(Component.java:4725)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:764)
	at java.awt.EventQueue.access$500(EventQueue.java:98)
	at java.awt.EventQueue$3.run(EventQueue.java:715)
	at java.awt.EventQueue$3.run(EventQueue.java:709)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
	at java.awt.EventQueue$4.run(EventQueue.java:737)
	at java.awt.EventQueue$4.run(EventQueue.java:735)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:734)
	at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:719)
	at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:664)
	at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:363)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:109)
	at java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:190)
	at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:235)
	at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:233)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:233)
	at java.awt.Dialog.show(Dialog.java:1077)
	at com.intellij.openapi.ui.impl.DialogWrapperPeerImpl$MyDialog.show(DialogWrapperPeerImpl.java:698)
	at com.intellij.openapi.ui.impl.DialogWrapperPeerImpl.show(DialogWrapperPeerImpl.java:430)
	at com.intellij.openapi.ui.DialogWrapper.invokeShow(DialogWrapper.java:1681)
	at com.intellij.openapi.ui.DialogWrapper.show(DialogWrapper.java:1630)
	at com.intellij.refactoring.ui.RefactoringDialog.show(RefactoringDialog.java:53)
	at com.intellij.refactoring.rename.PsiElementRenameHandler.rename(PsiElementRenameHandler.java:191)
	at com.intellij.refactoring.rename.PsiElementRenameHandler.rename(PsiElementRenameHandler.java:162)
	at com.intellij.refactoring.rename.PsiElementRenameHandler.invoke(PsiElementRenameHandler.java:112)
	at com.intellij.refactoring.rename.PsiElementRenameHandler.invoke(PsiElementRenameHandler.java:64)
	at com.intellij.refactoring.actions.BaseRefactoringAction.actionPerformed(BaseRefactoringAction.java:131)
	at com.intellij.openapi.actionSystem.ex.ActionUtil$1.run(ActionUtil.java:258)
	at com.intellij.openapi.application.TransactionGuardImpl.runSyncTransaction(TransactionGuardImpl.java:88)
	at com.intellij.openapi.application.TransactionGuardImpl.submitTransactionAndWait(TransactionGuardImpl.java:153)
	at com.intellij.openapi.actionSystem.ex.ActionUtil.performActionDumbAware(ActionUtil.java:273)
	at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.lambda$actionPerformed$0(ActionMenuItem.java:287)
	at com.intellij.openapi.wm.impl.FocusManagerImpl.runOnOwnContext(FocusManagerImpl.java:283)
	at com.intellij.openapi.wm.impl.IdeFocusManagerImpl.runOnOwnContext(IdeFocusManagerImpl.java:106)
	at com.intellij.openapi.actionSystem.impl.ActionMenuItem$ActionTransmitter.actionPerformed(ActionMenuItem.java:277)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
	at com.intellij.openapi.actionSystem.impl.ActionMenuItem.lambda$fireActionPerformed$0(ActionMenuItem.java:111)
	at com.intellij.openapi.application.TransactionGuardImpl.runSyncTransaction(TransactionGuardImpl.java:88)
	at com.intellij.openapi.application.TransactionGuardImpl.lambda$submitTransaction$1(TransactionGuardImpl.java:111)
	at com.intellij.openapi.application.TransactionGuardImpl.submitTransaction(TransactionGuardImpl.java:120)
	at com.intellij.openapi.application.TransactionGuard.submitTransaction(TransactionGuard.java:122)
	at com.intellij.openapi.actionSystem.impl.ActionMenuItem.fireActionPerformed(ActionMenuItem.java:111)
	at com.intellij.ui.plaf.beg.BegMenuItemUI.doClick(BegMenuItemUI.java:522)
	at com.intellij.ui.plaf.beg.BegMenuItemUI.access$300(BegMenuItemUI.java:35)
	at com.intellij.ui.plaf.beg.BegMenuItemUI$MyMouseInputHandler.mouseReleased(BegMenuItemUI.java:544)
	at java.awt.Component.processMouseEvent(Component.java:6548)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3325)
	at java.awt.Component.processEvent(Component.java:6313)
	at java.awt.Container.processEvent(Container.java:2237)
	at java.awt.Component.dispatchEventImpl(Component.java:4903)
	at java.awt.Container.dispatchEventImpl(Container.java:2295)
	at java.awt.Component.dispatchEvent(Component.java:4725)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4889)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4526)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4467)
	at java.awt.Container.dispatchEventImpl(Container.java:2281)
	at java.awt.Window.dispatchEventImpl(Window.java:2746)
	at java.awt.Component.dispatchEvent(Component.java:4725)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:764)
	at java.awt.EventQueue.access$500(EventQueue.java:98)
	at java.awt.EventQueue$3.run(EventQueue.java:715)
	at java.awt.EventQueue$3.run(EventQueue.java:709)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
	at java.awt.EventQueue$4.run(EventQueue.java:737)
	at java.awt.EventQueue$4.run(EventQueue.java:735)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:734)
	at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:719)
	at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:664)
	at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:363)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
```
</details>

## Steps to reproduce

1. Right click on tuple field usage.
2. Go to Refactor->Rename
3. Enter valid field name



Changed files:
src/main/kotlin/org/rust/ide/refactoring/RsRenameProcessor.kt

diff --git a/src/main/kotlin/org/rust/ide/refactoring/RsRenameProcessor.kt b/src/main/kotlin/org/rust/ide/refactoring/RsRenameProcessor.kt
index f57377b85..ed00c66b8 100644
--- a/src/main/kotlin/org/rust/ide/refactoring/RsRenameProcessor.kt
+++ b/src/main/kotlin/org/rust/ide/refactoring/RsRenameProcessor.kt
@@ -10,15 +10,12 @@ import com.intellij.openapi.util.Pass
 import com.intellij.psi.PsiElement
 import com.intellij.psi.search.SearchScope
 import com.intellij.refactoring.rename.RenamePsiElementProcessor
-import org.rust.lang.core.psi.RsLabel
-import org.rust.lang.core.psi.RsLabelDecl
-import org.rust.lang.core.psi.RsLifetime
-import org.rust.lang.core.psi.RsLifetimeParameter
+import org.rust.lang.core.psi.*
 import org.rust.lang.core.psi.ext.*
 
 class RsRenameProcessor : RenamePsiElementProcessor() {
 
-    override fun canProcessElement(element: PsiElement): Boolean = true
+    override fun canProcessElement(element: PsiElement): Boolean = element !is RsTupleFieldDecl
 
     override fun prepareRenaming(element: PsiElement, newName: String, allRenames: MutableMap<PsiElement, String>, scope: SearchScope) {
         if (element is RsLifetime || element is RsLifetimeParameter || element is RsLabel || element is RsLabelDecl) {