marcus.mews/PY-55691

PY-55691: `Expected type 'Type[AttrsInstance]'` warning passing `attrs` class to `attrs.fields()`

- add member __attrs_attrs__ to classes decorated with attrs.define or similar

Merge-request: IJ-MR-165647
Merged-by: Marcus Mews <marcus.mews@jetbrains.com>

GitOrigin-RevId: 979f894e595d903c55f33c8bd4c5c3d06cb2fe6d

python/python-psi-impl/resources/intellij.python.psi.impl.xml

@@ -563,6 +563,7 @@
     <inspectionExtension implementation="com.jetbrains.python.codeInsight.typing.PyTypingInspectionExtension"/>
     <customPackageIdentifier implementation="com.jetbrains.python.pyi.PyiCustomPackageIdentifier"/>
     <knownDecoratorProvider implementation="com.jetbrains.python.psi.PyStdKnownDecoratorProvider"/>
+    <pyClassMembersProvider implementation="com.jetbrains.python.codeInsight.PyAttrsClassMembersProvider"/>
 
     <!-- IPython -->
     <pyReferenceResolveProvider implementation="com.jetbrains.python.psi.resolve.PyIPythonBuiltinReferenceResolveProvider"/>

python/python-psi-impl/src/com/jetbrains/python/codeInsight/PyAttrsClassMembersProvider.java

@@ -0,0 +1,37 @@
+// Copyright 2000-2025 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.jetbrains.python.codeInsight;
+
+import com.intellij.psi.PsiElement;
+import com.jetbrains.python.PyNames;
+import com.jetbrains.python.psi.PyClass;
+import com.jetbrains.python.psi.impl.PyBuiltinCache;
+import com.jetbrains.python.psi.types.PyClassMembersProviderBase;
+import com.jetbrains.python.psi.types.PyClassType;
+import com.jetbrains.python.psi.types.TypeEvalContext;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+import static com.jetbrains.python.codeInsight.PyDataclassesKt.parseDataclassParameters;
+
+/**
+ * Adds member __attrs_attrs__ caused by decorator @attrs.define
+ */
+public final class PyAttrsClassMembersProvider extends PyClassMembersProviderBase {
+
+  @Override
+  public @NotNull Collection<PyCustomMember> getMembers(PyClassType clazz, PsiElement location, @NotNull TypeEvalContext context) {
+    PyClass pyClass = clazz.getPyClass();
+    PyDataclassParameters dataclassParameters = parseDataclassParameters(pyClass, context);
+    boolean hasAttrs = dataclassParameters != null && dataclassParameters.getType() == PyDataclassParameters.PredefinedType.ATTRS;
+    if (hasAttrs) {
+      PyBuiltinCache builtinCache = PyBuiltinCache.getInstance(pyClass);
+      PyClass objectClass = builtinCache.getClass(PyNames.OBJECT);
+      return List.of(new PyCustomMember("__attrs_attrs__", objectClass));
+    }
+    return Collections.emptyList();
+  }
+
+}

python/testSrc/com/jetbrains/python/Py3CompletionTest.java

@@ -389,6 +389,36 @@ public class Py3CompletionTest extends PyTestCase {
     );
   }
 
+  // PY-55691
+  public void testAttrsClassMembersProvider() {
+    runWithAdditionalClassEntryInSdkRoots(
+      "../packages",
+      () -> {
+        doTestByText(
+          """
+             import attrs
+             
+             @attrs.define
+             class User:
+                 password: str
+             
+             User().__at<caret>"""
+        );
+
+        myFixture.checkResult(
+          """
+             import attrs
+             
+             @attrs.define
+             class User:
+                 password: str
+             
+             User().__attrs_attrs__"""
+        );
+      }
+    );
+  }
+
   //PY-28332
   public void testImportNamespacePackageInMultipleRoots() {
     doMultiFileTest(Arrays.asList("root1/src", "root2/src"));

python/testSrc/com/jetbrains/python/inspections/Py3TypeCheckerInspectionTest.java

@@ -2894,4 +2894,35 @@ def foo(param: str | int) -> TypeGuard[str]:
                    f(<warning descr="Expected type 'Literal[1]', got 'Literal[2]' instead">a=2</warning>)
                    """);
   }
+
+  // PY-55691
+  public void testAttrsDataclassProtocolMatchingDefine() {
+    runWithAdditionalClassEntryInSdkRoots("packages", () ->
+      doTestByText("""
+                     import attrs
+                     
+                     @attrs.define
+                     class User:
+                         password: str
+                     
+                     attrs.fields(User)
+                     """)
+    );
+  }
+  
+  // PY-55691
+  public void testAttrsDataclassProtocolMatchingFrozen() {
+    runWithAdditionalClassEntryInSdkRoots("packages", () ->
+      doTestByText("""
+                     import attrs
+                     
+                     @attrs.frozen
+                     class User:
+                         password: str
+                     
+                     attrs.fields(User)
+                     """)
+    );
+  }
+
 }

python/testSrc/com/jetbrains/python/inspections/Py3UnresolvedReferencesInspectionTest.java

@@ -447,4 +447,21 @@ public class Py3UnresolvedReferencesInspectionTest extends PyInspectionTestCase
                          x.<warning descr="Cannot find reference 'is_integer' in 'T'">is_integer</warning>()  # E
                  """);
   }
+
+  // PY-55691
+  public void testAttrsClassMembersProviderAttrsProperty() {
+    runWithAdditionalClassEntryInSdkRoots("packages", () ->
+      doTestByText(
+          """
+            import attrs
+            
+            @attrs.define
+            class User:
+                password: str
+            
+            User().__attrs_attrs__ # OK
+            """)
+    );
+  }
+
 }