PY-20744 Compatibility inspection and annotator warn about variable annotations

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

@@ -284,4 +284,8 @@ public class PyElementVisitor extends PsiElementVisitor {
   public void visitPyTypeDeclarationStatement(PyTypeDeclarationStatement node) {
     visitPyStatement(node);
   }
+
+  public void visitPyAnnotation(PyAnnotation node) {
+    visitPyElement(node);
+  }
 }

python/src/com/jetbrains/python/psi/impl/PyAnnotationImpl.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.PyAnnotation;
+import com.jetbrains.python.psi.PyElementVisitor;
 import com.jetbrains.python.psi.PyExpression;
 import com.jetbrains.python.psi.stubs.PyAnnotationStub;
 import org.jetbrains.annotations.Nullable;
@@ -39,4 +40,9 @@ public class PyAnnotationImpl extends PyBaseElementImpl<PyAnnotationStub> implem
   public PyExpression getValue() {
     return findChildByClass(PyExpression.class);
   }
+
+  @Override
+  protected void acceptPyVisitor(PyElementVisitor pyVisitor) {
+    pyVisitor.visitPyAnnotation(this);
+  }
 }

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

@@ -60,6 +60,21 @@ public abstract class CompatibilityVisitor extends PyAnnotator {
     myVersionsToProcess = versionsToProcess;
   }
 
+  @Override
+  public void visitPyAnnotation(PyAnnotation node) {
+    final PsiElement parent = node.getParent();
+    if (!(parent instanceof PyFunction || parent instanceof PyNamedParameter)) {
+      final StringBuilder message = new StringBuilder(myCommonMessage);
+      int len = 0;
+      for (LanguageLevel languageLevel : myVersionsToProcess) {
+        if (languageLevel.isOlderThan(LanguageLevel.PYTHON36)) {
+          len = appendLanguageLevel(message, len, languageLevel);
+        }
+      }
+      commonRegisterProblem(message, " not support variable annotations", len, node, null);
+    }
+  }
+
   @Override
   public void visitPyDictCompExpression(PyDictCompExpression node) {
     super.visitPyDictCompExpression(node);

python/testData/highlighting/variableAnnotations.py

@@ -0,0 +1,8 @@
+class C:
+    x<error descr="Python version 3.5 does not support variable annotations">: int</error>
+    y<error descr="Python version 3.5 does not support variable annotations">: None</error> = 42
+
+    def m(self, d):
+        x<error descr="Python version 3.5 does not support variable annotations">: List[bool]</error>
+        d['foo']<error descr="Python version 3.5 does not support variable annotations">: str</error>
+        (d['bar'])<error descr="Python version 3.5 does not support variable annotations">: float</error>

python/testData/inspections/PyCompatibilityInspection/variableAnnotations.py

@@ -0,0 +1,8 @@
+class C:
+    x<warning descr="Python version 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 do not support variable annotations">: int</warning>
+    y<warning descr="Python version 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 do not support variable annotations">: None</warning> = 42
+
+    def m(self, d):
+        x<warning descr="Python version 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 do not support variable annotations">: List[bool]</warning>
+        d['foo']<warning descr="Python version 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 do not support variable annotations">: str</warning>
+        (d['bar'])<warning descr="Python version 2.4, 2.5, 2.6, 2.7, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5 do not support variable annotations">: float</warning>

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

@@ -293,6 +293,10 @@ public class PythonHighlightingTest extends PyTestCase {
     doTest(LanguageLevel.PYTHON35, true, false);
   }
 
+  public void testVariableAnnotations() {
+    doTest(LanguageLevel.PYTHON35, true, false);
+  }
+
   // ---
   private void doTest(final LanguageLevel languageLevel, final boolean checkWarnings, final boolean checkInfos) {
     PythonLanguageLevelPusher.setForcedLanguageLevel(myFixture.getProject(), languageLevel);

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

@@ -190,6 +190,10 @@ public class PyCompatibilityInspectionTest extends PyTestCase {
     doTest(LanguageLevel.PYTHON36);
   }
 
+  public void testVariableAnnotations() {
+    doTest(LanguageLevel.PYTHON36);
+  }
+
   private void doTest(@NotNull LanguageLevel level) {
     runWithLanguageLevel(level, this::doTest);
   }