PY-25157 Fixed: Inferred type shows incorrect return type with namedtuple

Implement equals and hashCode in PyNamedTupleType so different types are not the same.

python/src/com/jetbrains/python/codeInsight/stdlib/PyNamedTupleType.java

@@ -135,6 +135,23 @@ public class PyNamedTupleType extends PyClassTypeImpl implements PyCallableType
     return "PyNamedTupleType: " + myName;
   }
 
+  @Override
+  public boolean equals(Object o) {
+    if (o == this) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+    if (!super.equals(o)) return false;
+
+    final PyNamedTupleType type = (PyNamedTupleType)o;
+    return Objects.equals(myName, type.myName) &&
+           Objects.equals(myFields.keySet(), type.myFields.keySet()) &&
+           myDefinitionLevel == type.myDefinitionLevel;
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(super.hashCode(), myName, myFields.keySet(), myDefinitionLevel);
+  }
+
   @NotNull
   @Override
   public Set<String> getMemberNames(boolean inherited, @NotNull TypeEvalContext context) {

python/testSrc/com/jetbrains/python/PyTypeTest.java

@@ -2055,6 +2055,20 @@ public class PyTypeTest extends PyTestCase {
            "    expr = x");
   }
 
+  // PY-25157
+  public void testFunctionWithDifferentNamedTuplesAsParameterAndReturnTypes() {
+    runWithLanguageLevel(
+      LanguageLevel.PYTHON35,
+      () -> doTest("(a: MyType1) -> MyType2",
+                   "from collections import namedtuple\n" +
+                   "MyType1 = namedtuple('MyType1', 'x y')\n" +
+                   "MyType2 = namedtuple('MyType2', 'x y')\n" +
+                   "def foo(a: MyType1) -> MyType2:\n" +
+                   "    pass\n" +
+                   "expr = foo")
+    );
+  }
+
   private static List<TypeEvalContext> getTypeEvalContexts(@NotNull PyExpression element) {
     return ImmutableList.of(TypeEvalContext.codeAnalysis(element.getProject(), element.getContainingFile()).withTracing(),
                             TypeEvalContext.userInitiated(element.getProject(), element.getContainingFile()).withTracing());