From 9a1cfdb7a6ed18a508ff97222252d0958224f338 Mon Sep 17 00:00:00 2001
From: Mikhail Pyltsin <Mikhail.Pyltsin@jetbrains.com>
Date: Mon, 29 Sep 2025 12:07:55 +0200
Subject: [PATCH] [java-inspections] IDEA-379697 False warning about
 Comparator.nullsLast/nullsFirst passing null to comparator argument

GitOrigin-RevId: d3e361fa960d2b3ca36a54c98ccca4863c03c343
---
 .../dataFlow/fixture/ComparatorComparingContract.java  | 10 ++++++++++
 java/jdkAnnotations/java/util/annotations.xml          |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/ComparatorComparingContract.java b/java/java-tests/testData/inspection/dataFlow/fixture/ComparatorComparingContract.java
index ffe85e2141c5..e00e8fb1bd33 100644
--- a/java/java-tests/testData/inspection/dataFlow/fixture/ComparatorComparingContract.java
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/ComparatorComparingContract.java
@@ -2,6 +2,8 @@ import org.jetbrains.annotations.Nullable;
 
 import java.util.*;
 
+import static java.util.Comparator.*;
+
 public class ComparatorComparingContract {
   Comparator<MyObj> comparatorMR = Comparator.comparing(<warning descr="Function may return null, but it's not allowed here">MyObj::getName</warning>);
   Comparator<MyObj> comparatorLambda = Comparator.comparing(myObj -> <warning descr="Expression 'myObj.getName()' might evaluate to null but is returned by the method declared as @NotNull">myObj.getName()</warning>);
@@ -9,4 +11,12 @@ public class ComparatorComparingContract {
   interface MyObj {
     @Nullable String getName();
   }
+
+  public static List<Integer> nullComparator() {
+    final List<@Nullable Integer> list = new ArrayList<>();
+    list.add(null);
+    list.sort(nullsFirst(Integer::compareTo));
+    list.sort(nullsLast(Integer::compareTo));
+    return list;
+  }
 }
diff --git a/java/jdkAnnotations/java/util/annotations.xml b/java/jdkAnnotations/java/util/annotations.xml
index 81aba88a42be..21d527a59c92 100644
--- a/java/jdkAnnotations/java/util/annotations.xml
+++ b/java/jdkAnnotations/java/util/annotations.xml
@@ -2766,6 +2766,7 @@
   </item>
   <item name='java.util.Comparator java.util.Comparator&lt;T&gt; nullsFirst(java.util.Comparator&lt;? super T&gt;) 0'>
     <annotation name='org.jetbrains.annotations.Nullable'/>
+    <annotation name='org.jetbrains.annotations.NotNull' typePath="/1/*"/>
   </item>
   <item name='java.util.Comparator java.util.Comparator&lt;T&gt; nullsLast(java.util.Comparator&lt;? super T&gt;)'>
     <annotation name='org.jetbrains.annotations.NotNull'/>
@@ -2776,6 +2777,7 @@
   </item>
   <item name='java.util.Comparator java.util.Comparator&lt;T&gt; nullsLast(java.util.Comparator&lt;? super T&gt;) 0'>
     <annotation name='org.jetbrains.annotations.Nullable'/>
+    <annotation name='org.jetbrains.annotations.NotNull' typePath="/1/*"/>
   </item>
   <item name='java.util.Comparator java.util.Comparator&lt;T&gt; reverseOrder()'>
     <annotation name='org.jetbrains.annotations.NotNull'/>