From 5d115d4b22e36f56f4f41617ab0c4d1098b3bf2f Mon Sep 17 00:00:00 2001
From: "Ilya.Kazakevich" <Ilya.Kazakevich@jetbrains.com>
Date: Thu, 23 Jul 2015 18:55:30 +0300
Subject: [PATCH] Skipping ""Access to a protected member" for "_meta" for 
 PY-16477

---
 .../python/codeInsight/PyCustomMember.java    | 19 +++++++++++++++++++
 .../inspections/PyInspectionExtension.java    | 17 +++++++++++++----
 .../PyProtectedMemberInspection.java          |  5 +++++
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/python/psi-api/src/com/jetbrains/python/codeInsight/PyCustomMember.java b/python/psi-api/src/com/jetbrains/python/codeInsight/PyCustomMember.java
index 317db05c4ed9..cdca487cf05a 100644
--- a/python/psi-api/src/com/jetbrains/python/codeInsight/PyCustomMember.java
+++ b/python/psi-api/src/com/jetbrains/python/codeInsight/PyCustomMember.java
@@ -18,6 +18,8 @@ package com.jetbrains.python.codeInsight;
 import com.intellij.extapi.psi.ASTWrapperPsiElement;
 import com.intellij.icons.AllIcons;
 import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiPolyVariantReference;
+import com.intellij.psi.PsiReference;
 import com.intellij.util.Function;
 import com.jetbrains.python.psi.PyClass;
 import com.jetbrains.python.psi.PyFunction;
@@ -206,6 +208,19 @@ public class PyCustomMember {
     return myFunction;
   }
 
+  /**
+   * Checks if some reference points to this element
+   * @param reference reference to check
+   * @return true if reference points to it
+   */
+  public final boolean isReferenceToMe(@NotNull final PsiReference reference) {
+    final PsiElement element = reference.resolve();
+    if (!(element instanceof MyInstanceElement)) {
+      return false;
+    }
+    return ((MyInstanceElement)element).getThis().equals(this);
+  }
+
   private class MyInstanceElement extends ASTWrapperPsiElement implements PyTypedElement {
     private final PyClass myClass;
     private final PsiElement myContext;
@@ -216,6 +231,10 @@ public class PyCustomMember {
       myContext = context;
     }
 
+    private PyCustomMember getThis() {
+      return PyCustomMember.this;
+    }
+
     public PyType getType(@NotNull TypeEvalContext context, @NotNull TypeEvalContext.Key key) {
       if (myTypeCallback != null) {
         return myTypeCallback.fun(myContext);
diff --git a/python/psi-api/src/com/jetbrains/python/inspections/PyInspectionExtension.java b/python/psi-api/src/com/jetbrains/python/inspections/PyInspectionExtension.java
index fa5c893b1311..f11618d72e60 100644
--- a/python/psi-api/src/com/jetbrains/python/inspections/PyInspectionExtension.java
+++ b/python/psi-api/src/com/jetbrains/python/inspections/PyInspectionExtension.java
@@ -18,11 +18,9 @@ package com.jetbrains.python.inspections;
 import com.intellij.openapi.extensions.ExtensionPointName;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiReference;
-import com.jetbrains.python.psi.PyDocStringOwner;
-import com.jetbrains.python.psi.PyElement;
-import com.jetbrains.python.psi.PyFunction;
-import com.jetbrains.python.psi.PyQualifiedExpression;
+import com.jetbrains.python.psi.*;
 import com.jetbrains.python.psi.types.PyType;
+import com.jetbrains.python.psi.types.TypeEvalContext;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.List;
@@ -60,4 +58,15 @@ public abstract class PyInspectionExtension {
   public boolean ignoreUnresolvedMember(@NotNull PyType type, @NotNull String name) {
     return false;
   }
+
+  /**
+   * Returns true if access to protected (the one started with "_") symbol should not be treated as violation.
+   *
+   * @param expression access expression i.e. "_foo"
+   * @param context    type eval to be used
+   * @return true if ignore
+   */
+  public boolean ignoreProtectedSymbol(@NotNull final PyReferenceExpression expression, @NotNull final TypeEvalContext context) {
+    return false;
+  }
 }
diff --git a/python/src/com/jetbrains/python/inspections/PyProtectedMemberInspection.java b/python/src/com/jetbrains/python/inspections/PyProtectedMemberInspection.java
index 630ffbecd848..869105c1c8c1 100644
--- a/python/src/com/jetbrains/python/inspections/PyProtectedMemberInspection.java
+++ b/python/src/com/jetbrains/python/inspections/PyProtectedMemberInspection.java
@@ -103,6 +103,11 @@ public class PyProtectedMemberInspection extends PyInspection {
       if (name != null && name.startsWith("_") && !name.startsWith("__") && !name.endsWith("__")) {
         final PsiReference reference = node.getReference(getResolveContext());
         if (reference == null) return;
+        for (final PyInspectionExtension inspectionExtension : PyInspectionExtension.EP_NAME.getExtensions()) {
+          if (inspectionExtension.ignoreProtectedSymbol(node, myTypeEvalContext)) {
+            return;
+          }
+        }
         final PsiElement resolvedExpression = reference.resolve();
         final PyClass resolvedClass = getClassOwner(resolvedExpression);
         if (resolvedExpression instanceof PyTargetExpression) {