highlight star expression used outside of assignment context (PY-10177)

python/src/META-INF/python-core.xml

@@ -548,6 +548,7 @@
     <dumbAnnotator implementation="com.jetbrains.python.validation.DocStringAnnotator"/>
     <dumbAnnotator implementation="com.jetbrains.python.validation.PyDefinitionsAnnotator"/>
     <dumbAnnotator implementation="com.jetbrains.python.validation.GeneratorInArgumentListAnnotator"/>
+    <dumbAnnotator implementation="com.jetbrains.python.validation.StarAnnotator"/>
 
     <customTargetExpressionStubType implementation="com.jetbrains.python.psi.impl.stubs.PropertyStubType"/>
     <dialectsTokenSetContributor implementation="com.jetbrains.python.PythonTokenSetContributor"/>

python/src/com/jetbrains/python/validation/StarAnnotator.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2000-2013 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 com.jetbrains.python.validation;
+
+import com.jetbrains.python.psi.PyStarExpression;
+import com.jetbrains.python.psi.PyTargetExpression;
+
+/**
+ * @author yole
+ */
+public class StarAnnotator extends PyAnnotator {
+  @Override
+  public void visitPyStarExpression(PyStarExpression node) {
+    super.visitPyStarExpression(node);
+    if (!(node.getExpression() instanceof PyTargetExpression)) {
+      getHolder().createErrorAnnotation(node, "can use starred expression only as assignment target");
+    }
+  }
+}

python/testData/highlighting/starInGenerator.py

@@ -0,0 +1 @@
+y = (<error descr="can use starred expression only as assignment target">*()</error> for _ in ())

python/testSrc/com/jetbrains/python/PythonHighlightingTest.java

@@ -183,6 +183,10 @@ public class PythonHighlightingTest extends PyTestCase {
     doTest(false, false);
   }
 
+  public void testStarInGenerator() {  // PY-10177
+    doTest(LanguageLevel.PYTHON33, false, false);
+  }
+
   public void testStarArgs() {  // PY-6456
     doTest(LanguageLevel.PYTHON32, true, false);
   }