From 6a2e1fe28411936f1838f8475be6fd33921555cc Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Tue, 19 Aug 2014 11:08:25 +0200
Subject: [PATCH] IDEA-128242 Static code analysis reports "always true" for
 conditions that are always false

---
 .../dataFlow/DfaMemoryStateImpl.java          |  7 +++++
 .../dataFlow/value/DfaVariableValue.java      |  4 +++
 .../fixture/GetterResultsNotSame.java         | 26 +++++++++++++++++++
 .../DataFlowInspectionTest.java               |  1 +
 4 files changed, 38 insertions(+)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/GetterResultsNotSame.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
index 1b6d1dfedfec..3f0caf47679e 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
@@ -640,6 +640,13 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
       return true;
     }
 
+    if (dfaLeft == dfaRight) {
+      if (dfaLeft instanceof DfaVariableValue && ((DfaVariableValue)dfaLeft).containsCalls()) {
+        return true;
+      }
+      return !isNegated;
+    }
+
     if (isNull(dfaLeft) && isNotNull(dfaRight) || isNull(dfaRight) && isNotNull(dfaLeft)) {
       return isNegated;
     }
diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaVariableValue.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaVariableValue.java
index 3030bef32934..840103f5c993 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaVariableValue.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/value/DfaVariableValue.java
@@ -221,4 +221,8 @@ public class DfaVariableValue extends DfaValue {
     return true;
   }
 
+  public boolean containsCalls() {
+    return myVariable instanceof PsiMethod || myQualifier != null && myQualifier.containsCalls();
+  }
+
 }
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/GetterResultsNotSame.java b/java/java-tests/testData/inspection/dataFlow/fixture/GetterResultsNotSame.java
new file mode 100644
index 000000000000..1b60a7373900
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/GetterResultsNotSame.java
@@ -0,0 +1,26 @@
+class Main {
+
+  public static String getSameObject() {
+    return ""; // same object for any call
+  }
+
+  public static Main getNewObject() {
+    return new Main(); // different objects for different subsequent calls
+  }
+
+  public static void main(String[] args) {
+    Main m = new Main();
+
+    if (m.getSameObject() == m.getSameObject()) {
+      System.out.println("This will get printed");
+    }
+
+    if (m.getNewObject() == m.getNewObject()) {
+      System.out.println("This will not get printed");
+    }
+
+    if (Main.getNewObject() == Main.getNewObject()) {
+      System.out.println("This will not get printed");
+    }
+  }
+}
\ 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 33eb32eb0ec6..bd129b7aa3a6 100644
--- a/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java
+++ b/java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java
@@ -214,6 +214,7 @@ public class DataFlowInspectionTest extends LightCodeInsightFixtureTestCase {
   public void testNoConfusionWithAnonymousConstantInitializer() { doTest(); }
   public void testForeachOverWildcards() { doTest(); }
   public void testFinalGetter() { doTest(); }
+  public void testGetterResultsNotSame() { doTest(); }
 
   public void testByteBufferGetter() {
     myFixture.addClass("package java.nio; public class MappedByteBuffer { public int getInt() {} }");