From 5b3f88ca2c114fc240cb9e29b3d0bddd9ca7d5a0 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <tagir.valeev@jetbrains.com>
Date: Thu, 22 Jan 2026 13:41:51 +0100
Subject: [PATCH] IDEA-382900 [java-dfa] False positive null check inspection
 for Optional

Space-RevId: 1e8a9a958d359c00479687ccac4877b19a039cd8

GitOrigin-RevId: d4987256123b7a71c42f882138fec18b2ec34d91
---
 .../dataFlow/fixture/OptionalInference.java   | 53 +++++++++++++++++++
 .../daemon/inlays/AnnotationHintsTest.kt      |  4 +-
 .../DataFlowInspection21Test.java             |  4 ++
 java/jdkAnnotations/java/util/annotations.xml |  7 +++
 4 files changed, 66 insertions(+), 2 deletions(-)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/OptionalInference.java

diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/OptionalInference.java b/java/java-tests/testData/inspection/dataFlow/fixture/OptionalInference.java
new file mode 100644
index 000000000000..bfdbbc8109a2
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/OptionalInference.java
@@ -0,0 +1,53 @@
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+class NullTest {
+
+  enum StatusEnum {
+
+    OK(1, "OK"), ERROR(2, "ERROR");
+
+    final Integer code;
+
+    final String msg;
+
+    StatusEnum(Integer code, String msg) {
+      this.code = code;
+      this.msg = msg;
+    }
+  }
+
+  public static StatusEnum getInstance(Integer code) {
+    return Arrays.stream(StatusEnum.values())
+      .filter(it -> Objects.equals(it.code, code))
+      .findFirst()
+      .orElse(null);
+  }
+
+  public void test2() {
+    StatusEnum instance = getInstance(11);
+    if (instance == null) {
+      System.out.println("Instance not found");
+      return;
+    }
+    System.out.println(instance);
+  }
+
+  static String getString(List<String> list) {
+    return list.stream()
+      .findFirst()
+      .orElseGet(() -> null);
+  }
+
+  void testOrElseGet() {
+    if (getString(List.of()) == null) {
+      return;
+    }
+  }
+
+  static void main() {
+    new NullTest().test2();
+  }
+
+}
\ No newline at end of file
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/inlays/AnnotationHintsTest.kt b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/inlays/AnnotationHintsTest.kt
index 75835ad1c252..33d91fcfcd45 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/inlays/AnnotationHintsTest.kt
+++ b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/inlays/AnnotationHintsTest.kt
@@ -229,11 +229,11 @@ public final class Optional</*<# @NotNull #>*/T> {
         return this.isEmpty() ? Stream.empty() : Stream.of(this.value);
     }
 
-    /*<# @Contract(value = "!null -> !null", pure = true) #>*//*<# @Flow(sourceIsContainer = true) #>*/public T orElse(/*<# @Flow(targetIsContainer = true) #>*//*<# @Nullable #>*/T other) {
+    /*<# @Contract(value = "!null -> !null", pure = true) #>*//*<# @Flow(sourceIsContainer = true) #>*/public /*<# @Nullable #>*/T orElse(/*<# @Flow(targetIsContainer = true) #>*//*<# @Nullable #>*/T other) {
         return (T)(this.value != null ? this.value : other);
     }
 
-    public T orElseGet(Supplier<? extends T> supplier) {
+    public /*<# @UnknownNullability #>*/T orElseGet(Supplier<? extends /*<# @Nullable #>*/T> supplier) {
         return (T)(this.value != null ? this.value : supplier.get());
     }
 
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection21Test.java b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection21Test.java
index 2ee0476294bc..5ee592ebd4e0 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection21Test.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection21Test.java
@@ -254,4 +254,8 @@ public class DataFlowInspection21Test extends DataFlowInspectionTestCase {
     setupTypeUseAnnotations("org.jspecify.annotations", myFixture);
     doTest();
   }
+  
+  public void testOptionalInference() {
+    doTestWith((dfi, cvi) -> dfi.SUGGEST_NULLABLE_ANNOTATIONS = false);
+  }
 }
\ No newline at end of file
diff --git a/java/jdkAnnotations/java/util/annotations.xml b/java/jdkAnnotations/java/util/annotations.xml
index c82ab384cbff..139242e74152 100644
--- a/java/jdkAnnotations/java/util/annotations.xml
+++ b/java/jdkAnnotations/java/util/annotations.xml
@@ -4433,6 +4433,7 @@
     </annotation>
   </item>
   <item name='java.util.Optional T orElse(T)'>
+    <annotation name='org.jetbrains.annotations.Nullable'/>
     <annotation name='org.jetbrains.annotations.Contract'>
       <val name="value" val="&quot;!null -&gt; !null&quot;"/>
       <val name="pure" val="true"/>
@@ -4447,6 +4448,12 @@
       <val name="targetIsContainer" val="true"/>
     </annotation>
   </item>
+  <item name='java.util.Optional T orElseGet(java.util.function.Supplier&lt;? extends T&gt;)'>
+    <annotation name='org.jetbrains.annotations.UnknownNullability'/>
+  </item>
+  <item name='java.util.Optional T orElseGet(java.util.function.Supplier&lt;? extends T&gt;) 0'>
+    <annotation name='org.jetbrains.annotations.Nullable' typePath="/1/*"/>
+  </item>
   <item name='java.util.Optional T orElseThrow(java.util.function.Supplier&lt;? extends X&gt;) 0'>
       <annotation name='org.jetbrains.annotations.NotNull'/>
       <annotation name='org.jetbrains.annotations.NotNull' typePath="/1/*"/>