From 5d1e935acb8f586fedee61367ceddd4ba3c3954d Mon Sep 17 00:00:00 2001
From: Semyon Proshev <Semyon.Proshev@jetbrains.com>
Date: Wed, 14 Mar 2018 17:40:31 +0300
Subject: [PATCH] Highlight removing frozen dataclass attribute (PY-28957)

---
 .../inspections/PyDataclassInspection.kt      | 22 ++++++++++++++++---
 ...signmentsToFrozen.py => mutatingFrozen.py} | 11 +++++++++-
 .../PyDataclassInspectionTest.java            |  2 +-
 3 files changed, 30 insertions(+), 5 deletions(-)
 rename python/testData/inspections/PyDataclassInspection/{assignmentsToFrozen.py => mutatingFrozen.py} (69%)

diff --git a/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt b/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
index 8c8e9fde2b0f..2abaad0dddac 100644
--- a/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
+++ b/python/src/com/jetbrains/python/inspections/PyDataclassInspection.kt
@@ -37,9 +37,18 @@ class PyDataclassInspection : PyInspection() {
     override fun visitPyTargetExpression(node: PyTargetExpression?) {
       super.visitPyTargetExpression(node)
 
-      val cls = getInstancePyClass(node?.qualifier) ?: return
-      if (parseDataclassParameters(cls, myTypeEvalContext)?.frozen == true) {
-        registerProblem(node, "'${cls.name}' object attribute '${node!!.name}' is read-only", ProblemHighlightType.GENERIC_ERROR)
+      if (node != null) checkMutatingFrozenAttribute(node)
+    }
+
+    override fun visitPyDelStatement(node: PyDelStatement?) {
+      super.visitPyDelStatement(node)
+
+      if (node != null) {
+        node
+          .targets
+          .asSequence()
+          .filterIsInstance<PyReferenceExpression>()
+          .forEach { checkMutatingFrozenAttribute(it) }
       }
     }
 
@@ -158,6 +167,13 @@ class PyDataclassInspection : PyInspection() {
       }
     }
 
+    private fun checkMutatingFrozenAttribute(expression: PyQualifiedExpression) {
+      val cls = getInstancePyClass(expression.qualifier) ?: return
+      if (parseDataclassParameters(cls, myTypeEvalContext)?.frozen == true) {
+        registerProblem(expression, "'${cls.name}' object attribute '${expression.name}' is read-only", ProblemHighlightType.GENERIC_ERROR)
+      }
+    }
+
     private fun getInstancePyClass(element: PyTypedElement?): PyClass? {
       val type = element?.let { myTypeEvalContext.getType(it) } as? PyClassType
       return if (type != null && !type.isDefinition) type.pyClass else null
diff --git a/python/testData/inspections/PyDataclassInspection/assignmentsToFrozen.py b/python/testData/inspections/PyDataclassInspection/mutatingFrozen.py
similarity index 69%
rename from python/testData/inspections/PyDataclassInspection/assignmentsToFrozen.py
rename to python/testData/inspections/PyDataclassInspection/mutatingFrozen.py
index 5eeaced9e009..e12465e7a35b 100644
--- a/python/testData/inspections/PyDataclassInspection/assignmentsToFrozen.py
+++ b/python/testData/inspections/PyDataclassInspection/mutatingFrozen.py
@@ -12,6 +12,9 @@ b1 = B1(1, "2")
 b1.x = 2
 b1.y = "3"
 b1.z = 1.0
+del b1.x
+del b1.y
+del b1.z
 
 
 @dataclasses.dataclass(frozen=False)
@@ -25,6 +28,9 @@ b2 = B2(1, "2")
 b2.x = 2
 b2.y = "3"
 b2.z = 1.0
+del b2.x
+del b2.y
+del b2.z
 
 
 @dataclasses.dataclass(frozen=True)
@@ -37,4 +43,7 @@ B3.x = 5
 b3 = B3(1, "2")
 <error descr="'B3' object attribute 'x' is read-only">b3.x</error> = 2
 <error descr="'B3' object attribute 'y' is read-only">b3.y</error> = "3"
-<error descr="'B3' object attribute 'z' is read-only">b3.z</error> = 1.0
\ No newline at end of file
+<error descr="'B3' object attribute 'z' is read-only">b3.z</error> = 1.0
+del <error descr="'B3' object attribute 'x' is read-only">b3.x</error>
+del <error descr="'B3' object attribute 'y' is read-only">b3.y</error>
+del <error descr="'B3' object attribute 'z' is read-only">b3.z</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 aa6a3daec818..4f27c688815e 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyDataclassInspectionTest.java
@@ -12,7 +12,7 @@ import org.jetbrains.annotations.Nullable;
 public class PyDataclassInspectionTest extends PyInspectionTestCase {
 
   // PY-27398
-  public void testAssignmentsToFrozen() {
+  public void testMutatingFrozen() {
     doTest();
   }