From 4d0c8ab748513d87e1002f763003d4884716e8eb Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Sat, 13 Sep 2014 12:34:09 +0200
Subject: [PATCH] IDEA-127352 no warning when @NotNull annotated method returns
 null

---
 .../codeInspection/dataFlow/value/DfaConstValue.java  |  4 ++++
 .../dataFlow/fixture/ReturningNullConstant.java       | 11 +++++++++++
 .../codeInspection/DataFlowInspectionTest.java        |  1 +
 3 files changed, 16 insertions(+)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/ReturningNullConstant.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaConstValue.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaConstValue.java
index 5c8d7ca276d5..49028dd66e7b 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaConstValue.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaConstValue.java
@@ -70,6 +70,10 @@ public class DfaConstValue extends DfaValue {
           DfaConstValue unboxed = createFromValue(boo, PsiType.BOOLEAN, variable);
           return myFactory.getBoxedFactory().createBoxed(unboxed);
         }
+        PsiExpression initializer = variable.getInitializer();
+        if (initializer instanceof PsiLiteralExpression && initializer.textMatches(PsiKeyword.NULL)) {
+          return dfaNull;
+        }
         return null;
       }
       return createFromValue(value, type, variable);
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/ReturningNullConstant.java b/java/java-tests/testData/inspection/dataFlow/fixture/ReturningNullConstant.java
new file mode 100644
index 000000000000..4f9cfddc9f54
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/ReturningNullConstant.java
@@ -0,0 +1,11 @@
+import org.jetbrains.annotations.NotNull;
+
+class BrokenAlignment {
+
+  private static final String DEFAULT = null;
+
+  @NotNull
+  public String getDefaultValue() {
+    return <warning descr="Expression 'DEFAULT' might evaluate to null but is returned by the method declared as @NotNull">DEFAULT</warning>;
+  }
+}
\ No newline at end of file
diff --git a/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java b/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java
index 0acf071bbf4a..490ded30353c 100644
--- a/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java
+++ b/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java
@@ -111,6 +111,7 @@ public class DataFlowInspectionTest extends LightCodeInsightFixtureTestCase {
   public void testSynchronizingOnNullable() throws Throwable { doTest(); }
   public void testSwitchOnNullable() { doTest(); }
   public void testReturningNullFromVoidMethod() throws Throwable { doTest(); }
+  public void testReturningNullConstant() { doTest(); }
 
   public void testCatchRuntimeException() throws Throwable { doTest(); }
   // IDEA-129331