fixed PY-6589 Unnecessary backslash in expression: false negative for double parenthesis

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

@@ -5,8 +5,8 @@ import com.intellij.codeInspection.ProblemsHolder;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiElementVisitor;
 import com.intellij.psi.PsiWhiteSpace;
+import com.intellij.psi.search.PsiElementProcessor;
 import com.intellij.psi.util.PsiTreeUtil;
-import com.intellij.util.containers.Stack;
 import com.jetbrains.python.PyBundle;
 import com.jetbrains.python.actions.RemoveUnnecessaryBackslashQuickFix;
 import com.jetbrains.python.psi.*;
@@ -53,17 +53,7 @@ public class PyUnnecessaryBackslashInspection extends PyInspection {
 
     @Override
     public void visitPyParenthesizedExpression(final PyParenthesizedExpression expression) {
-      Stack<PsiElement> stack = new Stack<PsiElement>();
-      stack.push(expression.getContainedExpression());
-      while (!stack.isEmpty()) {
-        PsiElement element = stack.pop();
-        findProblem(element);
-        if (element != null) {
-          for (PsiElement psiElement : element.getChildren()) {
-            stack.push(psiElement);
-          }
-        }
-      }
+      findProblem(expression);
     }
 
     @Override
@@ -92,14 +82,15 @@ public class PyUnnecessaryBackslashInspection extends PyInspection {
     }
 
     private void findProblem(@Nullable final PsiElement expression) {
-      PsiWhiteSpace[] children = PsiTreeUtil.getChildrenOfType(expression, PsiWhiteSpace.class);
-      if (children != null) {
-        for (PsiWhiteSpace ws : children) {
-          if (ws.getText().contains("\\")) {
+      PsiTreeUtil.processElements(expression, new PsiElementProcessor<PsiElement>() {
+        @Override
+        public boolean execute(@NotNull PsiElement ws) {
+          if (ws instanceof PsiWhiteSpace && ws.getText().contains("\\")) {
             registerProblem(ws, "Unnecessary backslash in expression.", new RemoveUnnecessaryBackslashQuickFix());
           }
+          return true;
         }
-      }
+      });
     }
   }
 }

python/testData/inspections/PyUnnecessaryBackslashInspection/test.py

@@ -52,3 +52,9 @@ v = [ "some"<warning descr="Unnecessary backslash in expression."> \</warning>
 
 a = func('some '<warning descr="Unnecessary backslash in expression."> \</warning>
          'string')
+
+
+#PY-6589
+a = ( <warning descr="Unnecessary backslash in expression."> \</warning>
+(1, <warning descr="Unnecessary backslash in expression."> \</warning>
+2),2)