From f65c12ccbd8a39b90037cd4071cc27782ebe8bc4 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Wed, 7 Oct 2020 10:54:49 +0700
Subject: [PATCH] [java-dfa] Do not allow null in ephemeral value

GitOrigin-RevId: cca32e434c96998346fc6759f3d699bc6ada799a
---
 .../dataFlow/types/DfGenericObjectType.java    |  8 +++++---
 .../dataFlow/fixture/EphemeralInIfChain.java   | 18 ++++++++++++++++--
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/types/DfGenericObjectType.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/types/DfGenericObjectType.java
index 534347174e8e..65e1e3e64ace 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/types/DfGenericObjectType.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/types/DfGenericObjectType.java
@@ -249,9 +249,11 @@ class DfGenericObjectType extends DfAntiConstantType<Object> implements DfRefere
       } else if (!myNotValues.containsAll(otherNotValues)) {
         notValues = new THashSet<>(myNotValues);
         notValues.addAll(otherNotValues);
-        DfEphemeralReferenceType ephemeralValue = checkEphemeral(constraint, notValues);
-        if (ephemeralValue != null) {
-          return ephemeralValue;
+        if (nullability == DfaNullability.NOT_NULL) {
+          DfEphemeralReferenceType ephemeralValue = checkEphemeral(constraint, notValues);
+          if (ephemeralValue != null) {
+            return ephemeralValue;
+          }
         }
       }
     }
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/EphemeralInIfChain.java b/java/java-tests/testData/inspection/dataFlow/fixture/EphemeralInIfChain.java
index 38e606f9dcb8..a483a4808142 100644
--- a/java/java-tests/testData/inspection/dataFlow/fixture/EphemeralInIfChain.java
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/EphemeralInIfChain.java
@@ -14,10 +14,24 @@ class Test {
     else if (x == MyEnum.C) {
       s = "C";
     }
-    System.out.println(s.trim());
+    System.out.println(s.<warning descr="Method invocation 'trim' may produce 'NullPointerException'">trim</warning>()); // reachable if x is null
   }
 
-  void test2(MyEnum x) {
+  void test1(@NotNull MyEnum x) {
+    String s = null;
+    if (x == MyEnum.A) {
+      s = "A";
+    }
+    else if (x == MyEnum.B) {
+      s = "B";
+    }
+    else if (x == MyEnum.C) {
+      s = "C";
+    }
+    System.out.println(s.trim()); // ephemerably reachable
+  }
+
+  void test2(@NotNull MyEnum x) {
     String s = null;
     if (x == MyEnum.A) {
       s = "A";