Ignore underscores in PyAssignmentToLoopOrWithParameterInspection

PY-26137 fixed.

python/src/com/jetbrains/python/inspections/PyAssignmentToLoopOrWithParameterInspection.java

@@ -1,21 +1,6 @@
-/*
- * Copyright 2000-2014 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.
- */
+// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.jetbrains.python.inspections;
 
-import com.google.common.collect.Lists;
 import com.intellij.codeInspection.LocalInspectionToolSession;
 import com.intellij.codeInspection.ProblemsHolder;
 import com.intellij.openapi.util.Condition;
@@ -23,12 +8,15 @@ import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiElementVisitor;
 import com.intellij.psi.PsiReference;
 import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.util.containers.ContainerUtil;
 import com.jetbrains.python.PyBundle;
+import com.jetbrains.python.PyNames;
 import com.jetbrains.python.codeInsight.controlflow.ScopeOwner;
 import com.jetbrains.python.psi.*;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
@@ -51,7 +39,6 @@ public class PyAssignmentToLoopOrWithParameterInspection extends PyInspection {
     return NAME;
   }
 
-
   @NotNull
   @Override
   public PsiElementVisitor buildVisitor(@NotNull final ProblemsHolder holder,
@@ -80,7 +67,7 @@ public class PyAssignmentToLoopOrWithParameterInspection extends PyInspection {
      * that declares one of names, declared in this statement
      */
     private void checkNotReDeclaringUpperLoopOrStatement(@NotNull final PsiElement statement) {
-      for (final PsiElement declaredVar : getNamedElementsOfForAndWithStatements(statement)) {
+      for (PyExpression declaredVar : getNamedElementsOfForAndWithStatements(statement)) {
         final Filter filter = new Filter(handleSubscriptionsAndResolveSafely(declaredVar));
         final PsiElement firstParent = PsiTreeUtil.findFirstParent(statement, true, filter);
         if ((firstParent != null) && isRequiredStatement(firstParent)) {
@@ -132,8 +119,8 @@ public class PyAssignmentToLoopOrWithParameterInspection extends PyInspection {
       if (!isRequiredStatement(psiElement)) {
         return false; //Parent has wrong type, skip
       }
-      final List<PyElement> varsDeclaredInStatement = getNamedElementsOfForAndWithStatements(psiElement);
-      for (final PsiElement varDeclaredInStatement : varsDeclaredInStatement) {
+      final List<PyExpression> varsDeclaredInStatement = getNamedElementsOfForAndWithStatements(psiElement);
+      for (PyExpression varDeclaredInStatement : varsDeclaredInStatement) {
         //For each variable, declared by this parent take first declaration and open subscription list if any
         final PsiReference reference = handleSubscriptionsAndResolveSafely(varDeclaredInStatement).getReference();
         if ((reference != null) && reference.isReferenceTo(myNode)) {
@@ -151,13 +138,12 @@ public class PyAssignmentToLoopOrWithParameterInspection extends PyInspection {
    * @param element element to open and resolve
    * @return opened and resolved element
    */
-  private static PsiElement handleSubscriptionsAndResolveSafely(PsiElement element) {
-    assert element != null;
+  @NotNull
+  private static PsiElement handleSubscriptionsAndResolveSafely(@NotNull PyExpression element) {
     if (element instanceof PySubscriptionExpression) {
       element = ((PySubscriptionExpression)element).getRootOperand();
     }
-    element = PyUtil.resolveToTheTop(element);
-    return element;
+    return PyUtil.resolveToTheTop(element);
   }
 
   /**
@@ -171,28 +157,34 @@ public class PyAssignmentToLoopOrWithParameterInspection extends PyInspection {
     return (element instanceof PyWithStatement) || (element instanceof PyForStatement);
   }
 
-  private static List<PyElement> getNamedElementsOfForAndWithStatements(@NotNull PsiElement element) {
-    final List<PyElement> expressions;
+  @NotNull
+  private static List<PyExpression> getNamedElementsOfForAndWithStatements(@NotNull PsiElement element) {
     if (element instanceof PyForStatement) {
-      final PyForStatement forStmt = (PyForStatement)element;
-      final PyExpression tgt = forStmt.getForPart().getTarget();
-      expressions = Lists.newArrayList();
-      expressions.addAll(PyUtil.flattenedParensAndStars(tgt));
+      final PyForStatement forStatement = (PyForStatement)element;
+      final PyExpression target = forStatement.getForPart().getTarget();
+
+      return dropUnderscores(PyUtil.flattenedParensAndStars(target));
     }
     else if (element instanceof PyWithStatement) {
-      final PyWithStatement withStmt = (PyWithStatement)element;
-      expressions = Lists.newArrayList();
-      final PyWithItem[] items = PsiTreeUtil.getChildrenOfType(withStmt, PyWithItem.class);
-      if (items != null) {
-        for (PyWithItem item : items) {
-          PyExpression targetExpression = item.getTarget();
-          expressions.addAll(PyUtil.flattenedParensAndTuples(targetExpression));
+      final PyWithStatement withStatement = (PyWithStatement)element;
+      final List<PyExpression> result = new ArrayList<>();
+
+      for (PyWithItem item : withStatement.getWithItems()) {
+        final PyExpression target = item.getTarget();
+        if (target != null) {
+          result.addAll(PyUtil.flattenedParensAndTuples(target));
         }
       }
+
+      return dropUnderscores(result);
     }
-    else {
-      expressions = Collections.emptyList();
-    }
-    return expressions;
+
+    return Collections.emptyList();
+  }
+
+  @NotNull
+  private static List<PyExpression> dropUnderscores(@NotNull List<PyExpression> expressions) {
+    return ContainerUtil.filter(expressions,
+                                expression -> !PyNames.UNDERSCORE.equals(expression.getText()));
   }
 }

python/testData/inspections/PyAssignmentToLoopOrWithParameterInspection/redeclaredUnderscore.py

@@ -0,0 +1,3 @@
+for _ in []:
+    for _ in []:
+        print("ok")

python/testSrc/com/jetbrains/python/inspections/PyAssignmentToLoopOrWithParameterInspectionTest.java

@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2014 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.
- */
+// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.jetbrains.python.inspections;
 
 import com.jetbrains.python.fixtures.PyInspectionTestCase;
@@ -31,6 +17,11 @@ public class PyAssignmentToLoopOrWithParameterInspectionTest extends PyInspectio
     doTest();
   }
 
+  // PY-26137
+  public void testRedeclaredUnderscore() {
+    doTest();
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {