fixed PY-10342 Instance attribute defined outside init: detect functions called in init

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

@@ -67,6 +67,8 @@ public class PyAttributeOutsideInitInspection extends PyInspection {
     public void visitPyFunction(PyFunction node) {
       final PyClass containingClass = node.getContainingClass();
       if (containingClass == null) return;
+      final String name = node.getName();
+      if (name != null && name.startsWith("_")) return;
       if (!isApplicable(containingClass)) {
         return;
       }

python/testData/inspections/PyAttributeOutsideInitInspection/privateMethod.py

@@ -0,0 +1,8 @@
+
+class MyClass(object):
+    def __init__(self):
+        self._resetData()
+        self._val  = []
+
+    def _resetData(self):
+        self._val = []  # This should not be receiving a warning. The function gets called in __init__.

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

@@ -66,6 +66,10 @@ public class PyAttributeOutsideInitInspectionTest extends PyTestCase {
     doTest();
   }
 
+  public void testPrivateMethod() {
+    doTest();
+  }
+
   private void doTest() {
     myFixture.configureByFile("inspections/PyAttributeOutsideInitInspection/" + getTestName(true) + ".py");
     myFixture.enableInspections(PyAttributeOutsideInitInspection.class);