From 315b33c41fd0030bd83eb4bcb957f246ff8902f1 Mon Sep 17 00:00:00 2001
From: Semyon Proshev <Semyon.Proshev@jetbrains.com>
Date: Thu, 11 Jan 2018 17:58:03 +0300
Subject: [PATCH] Highlight the case when `default` and `default_factory` are
 specified (PY-27398)

---
 .../python/inspections/PyDataclassInspection.kt   | 15 +++++++++++++--
 .../fieldDefaultAndDefaultFactory.py              |  7 +++++++
 .../inspections/PyDataclassInspectionTest.java    |  5 +++++
 3 files changed, 25 insertions(+), 2 deletions(-)
 create mode 100644 python/testData/inspections/PyDataclassInspection/fieldDefaultAndDefaultFactory.py

diff --git a/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt b/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
index bb267e2a357e..d5e2d8058b4e 100644
--- a/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
+++ b/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
@@ -16,6 +16,7 @@ import com.jetbrains.python.codeInsight.typing.PyTypingTypeProvider
 import com.jetbrains.python.psi.*
 import com.jetbrains.python.psi.impl.PyBuiltinCache
 import com.jetbrains.python.psi.impl.PyCallExpressionHelper
+import com.jetbrains.python.psi.impl.stubs.PyDataclassFieldStubImpl
 import com.jetbrains.python.psi.resolve.PyResolveContext
 import com.jetbrains.python.psi.types.*
 
@@ -55,8 +56,9 @@ class PyDataclassInspection : PyInspection() {
 
           node.processClassLevelDeclarations { element, _ ->
             if (element is PyTargetExpression && !PyTypingTypeProvider.isClassVar(element, myTypeEvalContext)) {
-                processDefaultFieldValue(element)
-                processAsInitVar(element, postInit)?.let { initVars.add(it) }
+              processDefaultFieldValue(element)
+              processAsInitVar(element, postInit)?.let { initVars.add(it) }
+              processFieldFunctionCall(element)
             }
 
             true
@@ -189,6 +191,15 @@ class PyDataclassInspection : PyInspection() {
       return null
     }
 
+    private fun processFieldFunctionCall(field: PyTargetExpression) {
+      val fieldStub = PyDataclassFieldStubImpl.create(field)
+      if (fieldStub != null && fieldStub.hasDefault() && fieldStub.hasDefaultFactory()) {
+        val call = field.findAssignedValue() as? PyCallExpression ?: return
+
+        registerProblem(call.argumentList, "cannot specify both default and default_factory", ProblemHighlightType.GENERIC_ERROR)
+      }
+    }
+
     private fun processPostInitDefinition(postInit: PyFunction,
                                           dataclassParameters: DataclassParameters,
                                           initVars: List<PyTargetExpression>) {
diff --git a/python/testData/inspections/PyDataclassInspection/fieldDefaultAndDefaultFactory.py b/python/testData/inspections/PyDataclassInspection/fieldDefaultAndDefaultFactory.py
new file mode 100644
index 000000000000..e4b41db46488
--- /dev/null
+++ b/python/testData/inspections/PyDataclassInspection/fieldDefaultAndDefaultFactory.py
@@ -0,0 +1,7 @@
+import dataclasses
+
+@dataclasses.dataclass
+class E1:
+    a: int = dataclasses.field(default=1)
+    b: int = dataclasses.field(default_factory=int)
+    c: int = dataclasses.field<error descr="cannot specify both default and default_factory">(default=1, default_factory=int)</error>
\ No newline at end of file
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java
index acb0fb96a129..68d4c47141dd 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java
@@ -71,6 +71,11 @@ public class PyDataclassInspectionTest extends PyInspectionTestCase {
     doTest();
   }
 
+  // PY-27398
+  public void testFieldDefaultAndDefaultFactory() {
+    doTest();
+  }
+
   @Override
   protected void doTest() {
     runWithLanguageLevel(