PY-623

"Unused assignment" false positive

python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java

@@ -47,6 +47,16 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
     super.visitPyStatement(node);
   }
 
+  @Override
+  public void visitPySubscriptionExpression(PySubscriptionExpression node) {
+    myBuilder.startNode(node);
+    node.getOperand().accept(this);
+    final PyExpression expression = node.getIndexExpression();
+    if (expression != null) {
+      expression.accept(this);
+    }
+  }
+
   @Override
   public void visitPyReferenceExpression(final PyReferenceExpression node) {
     final PyExpression qualifier = node.getQualifier();

python/src/com/jetbrains/python/psi/PyElementVisitor.java

@@ -17,6 +17,7 @@
 package com.jetbrains.python.psi;
 
 import com.intellij.psi.PsiElementVisitor;
+import com.jetbrains.python.psi.impl.PySubscriptionExpressionImpl;
 
 /**
  * Visitor for python-specific nodes.
@@ -225,4 +226,8 @@ public class PyElementVisitor extends PsiElementVisitor {
   public void visitPyStarExpression(PyStarExpression node) {
     visitPyExpression(node);
   }
+
+  public void visitPySubscriptionExpression(PySubscriptionExpression node) {
+    visitPyExpression(node);
+  }
 }

python/src/com/jetbrains/python/psi/impl/PyAssignmentStatementImpl.java

@@ -58,7 +58,7 @@ public class PyAssignmentStatementImpl extends PyElementImpl implements PyAssign
     List<PyExpression> candidates = PyUtil.flattenedParens(psi_nodes); // put all possible tuples to one level
     List<PyExpression> targets = new ArrayList<PyExpression>();
     for (PyExpression expr : candidates) { // only filter out targets
-      if (expr instanceof PyTargetExpression) {
+      if (expr instanceof PyTargetExpression || expr instanceof PySubscriptionExpression) {
         targets.add(expr);
       }
     }

python/src/com/jetbrains/python/psi/impl/PySubscriptionExpressionImpl.java

@@ -18,6 +18,7 @@ package com.jetbrains.python.psi.impl;
 
 import com.intellij.lang.ASTNode;
 import com.jetbrains.python.PyElementTypes;
+import com.jetbrains.python.psi.PyElementVisitor;
 import com.jetbrains.python.psi.PyExpression;
 import com.jetbrains.python.psi.PySubscriptionExpression;
 import com.jetbrains.python.psi.types.PyType;
@@ -44,6 +45,11 @@ public class PySubscriptionExpressionImpl extends PyElementImpl implements PySub
     return childToPsi(PyElementTypes.EXPRESSIONS, 1);
   }
 
+  @Override
+  protected void acceptPyVisitor(final PyElementVisitor pyVisitor) {
+    pyVisitor.visitPySubscriptionExpression(this);
+  }
+
   public PyType getType() {
     return null;
   }