From 689c091fd7c8c0156dba19fa5eb9bd08409d9694 Mon Sep 17 00:00:00 2001
From: Mikhail Golubev <mikhail.golubev@jetbrains.com>
Date: Wed, 12 Jul 2017 19:47:18 +0300
Subject: [PATCH] PY-24260 Don't check equality of PyGenericTypes using "==",
 they are not interned

Because we represent both "Type[T]" and "T" as immutable instances of
PyGenericType with different values of isDefinition flag and handle
transition between them in PyTypeChecker.substitute() by creating new
instances of the opposite kind, we can end up searching for the mapping
for "T" in the cache already containing "Type[T]" -> "Type[T]" over and
over again until SOE.
---
 .../python/psi/types/PyTypeChecker.java       |  2 +-
 .../com/jetbrains/python/PyTypingTest.java    | 19 +++++++++++++++----
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/python/src/com/jetbrains/python/psi/types/PyTypeChecker.java b/python/src/com/jetbrains/python/psi/types/PyTypeChecker.java
index 1b569176e27e..9827cdce647d 100644
--- a/python/src/com/jetbrains/python/psi/types/PyTypeChecker.java
+++ b/python/src/com/jetbrains/python/psi/types/PyTypeChecker.java
@@ -470,7 +470,7 @@ public class PyTypeChecker {
             }
           }
         }
-        if (substitution instanceof PyGenericType && substitution != type) {
+        if (substitution instanceof PyGenericType && !typeVar.equals(substitution)) {
           final PyType recursive = substitute(substitution, substitutions, context);
           if (recursive != null) {
             return recursive;
diff --git a/python/testSrc/com/jetbrains/python/PyTypingTest.java b/python/testSrc/com/jetbrains/python/PyTypingTest.java
index 88e96144e56a..369f12d99800 100644
--- a/python/testSrc/com/jetbrains/python/PyTypingTest.java
+++ b/python/testSrc/com/jetbrains/python/PyTypingTest.java
@@ -16,13 +16,9 @@
 package com.jetbrains.python;
 
 import com.intellij.lang.injection.InjectedLanguageManager;
-import com.intellij.openapi.editor.Document;
-import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.util.TextRange;
-import com.intellij.psi.PsiDocumentManager;
 import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiFile;
 import com.intellij.psi.PsiLanguageInjectionHost;
 import com.intellij.testFramework.LightProjectDescriptor;
 import com.jetbrains.python.documentation.PythonDocumentationProvider;
@@ -957,6 +953,21 @@ public class PyTypingTest extends PyTestCase {
            "expr = f(True, 1, 'foo')\n");
   }
 
+  // PY-24260
+  public void testGenericClassParameterTakenFromGenericClassObject() {
+    doTest("MyClass[TypeVar('T')]",
+           "from typing import TypeVar, Generic, Type\n" +
+           "\n" +
+           "T = TypeVar(\"T\")\n" +
+           "\n" +
+           "class MyClass(Generic[T]):\n" +
+           "    def __init__(self, type: Type[T]):\n" +
+           "        pass\n" +
+           "\n" +
+           "def f(x: Type[T]):\n" +
+           "    expr = MyClass(x)\n");
+  }
+
   private void doTestNoInjectedText(@NotNull String text) {
     myFixture.configureByText(PythonFileType.INSTANCE, text);
     final InjectedLanguageManager languageManager = InjectedLanguageManager.getInstance(myFixture.getProject());