PY-19130 Fixed: Type inference: decorators behaving oddly

If class is decorated, PyArgumentListInspection doesn't check its constructor arguments

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import com.intellij.codeInspection.LocalQuickFix;
 import com.intellij.codeInspection.ProblemsHolder;
 import com.intellij.lang.ASTNode;
 import com.intellij.psi.PsiElementVisitor;
+import com.intellij.psi.PsiPolyVariantReference;
+import com.intellij.psi.ResolveResult;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.jetbrains.python.PyBundle;
 import com.jetbrains.python.PyNames;
@@ -35,7 +37,9 @@ import com.jetbrains.python.psi.types.PyTypeChecker;
 import com.jetbrains.python.psi.types.TypeEvalContext;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
+import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -115,9 +119,13 @@ public class PyArgumentListInspection extends PyInspection {
     final PyCallExpression.PyMarkedCallee callee = mapping.getMarkedCallee();
     if (callee != null) {
       final PyCallable callable = callee.getCallable();
-      // Decorate functions may have different parameter lists. We don't match arguments with parameters of decorators yet
-      if (callable instanceof PyFunction && PyUtil.hasCustomDecorators((PyFunction)callable)) {
-        return;
+      if (callable instanceof PyFunction) {
+        final PyFunction function = (PyFunction)callable;
+
+        // Decorate functions may have different parameter lists. We don't match arguments with parameters of decorators yet
+        if (PyUtil.hasCustomDecorators(function) || decoratedClassInitCall(callExpr.getCallee(), function)) {
+          return;
+        }
       }
     }
     highlightParametersMismatch(node, holder, mapping);
@@ -128,6 +136,19 @@ public class PyArgumentListInspection extends PyInspection {
     inspectPyArgumentList(node, holder, context, 0);
   }
 
+  private static boolean decoratedClassInitCall(@Nullable PyExpression callee, @NotNull PyFunction function) {
+    if (callee instanceof PyReferenceExpression && PyUtil.isInit(function)) {
+      final PsiPolyVariantReference classReference = ((PyReferenceExpression)callee).getReference();
+
+      return Arrays
+        .stream(classReference.multiResolve(false))
+        .map(ResolveResult::getElement)
+        .anyMatch(element -> element instanceof PyClass && PyUtil.hasCustomDecorators((PyClass)element));
+    }
+
+    return false;
+  }
+
   private static void highlightStarArgumentTypeMismatch(PyArgumentList node, ProblemsHolder holder, TypeEvalContext context) {
     for (PyExpression arg : node.getArguments()) {
       if (arg instanceof PyStarArgument) {

python/testData/inspections/PyArgumentListInspection/classDecoratedThroughCall.py

@@ -0,0 +1,8 @@
+import attr
+
+class A(object):
+    a = attr.ib()
+
+A = attr.s(A)
+
+A(a="test")

python/testData/inspections/PyArgumentListInspection/classDecoratedThroughDecorator.py

@@ -0,0 +1,7 @@
+import attr
+
+@attr.s
+class A(object):
+    a = attr.ib()
+
+A(a="test")

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2013 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -44,6 +44,16 @@ public class PyArgumentListInspectionTest extends PyTestCase {
       PythonLanguageLevelPusher.setForcedLanguageLevel(myFixture.getProject(), null);
     }
   }
+
+  // PY-19130
+  public void testClassDecoratedThroughDecorator() {
+    doTest();
+  }
+
+  // PY-19130
+  public void testClassDecoratedThroughCall() {
+    doTest();
+  }
   
   public void testTupleVsLiteralList() {
     doTest();