From 19ffdbe7aa68045d0a5e8fee2b3113d90b7d3ad7 Mon Sep 17 00:00:00 2001
From: peter <peter@jetbrains.com>
Date: Thu, 22 Dec 2016 15:12:03 +0100
Subject: [PATCH] avoid false positive contract violations when the control
 flow goes through unknown conditions (IDEA-164883)

---
 .../codeInspection/dataFlow/ContractChecker.java   | 14 ++++++--------
 .../dataFlow/contractCheck/UnknownIfCondition.java | 12 ++++++++++++
 .../intellij/codeInspection/ContractCheckTest.java |  1 +
 3 files changed, 19 insertions(+), 8 deletions(-)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/contractCheck/UnknownIfCondition.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/ContractChecker.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/ContractChecker.java
index 98f5446a6f2d..b9a160440209 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/ContractChecker.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/ContractChecker.java
@@ -15,14 +15,8 @@
  */
 package com.intellij.codeInspection.dataFlow;
 
-import com.intellij.codeInspection.dataFlow.instructions.CheckReturnValueInstruction;
-import com.intellij.codeInspection.dataFlow.instructions.Instruction;
-import com.intellij.codeInspection.dataFlow.instructions.MethodCallInstruction;
-import com.intellij.codeInspection.dataFlow.instructions.ReturnInstruction;
-import com.intellij.codeInspection.dataFlow.value.DfaConstValue;
-import com.intellij.codeInspection.dataFlow.value.DfaValue;
-import com.intellij.codeInspection.dataFlow.value.DfaValueFactory;
-import com.intellij.codeInspection.dataFlow.value.DfaVariableValue;
+import com.intellij.codeInspection.dataFlow.instructions.*;
+import com.intellij.codeInspection.dataFlow.value.*;
 import com.intellij.psi.*;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
@@ -104,6 +98,10 @@ class ContractChecker extends DataFlowRunner {
       return DfaInstructionState.EMPTY_ARRAY;
     }
 
+    if (instruction instanceof ConditionalGotoInstruction && memState.peek() == DfaUnknownValue.getInstance()) {
+      return DfaInstructionState.EMPTY_ARRAY;
+    }
+
     return super.acceptInstruction(visitor, instructionState);
   }
 
diff --git a/java/java-tests/testData/inspection/dataFlow/contractCheck/UnknownIfCondition.java b/java/java-tests/testData/inspection/dataFlow/contractCheck/UnknownIfCondition.java
new file mode 100644
index 000000000000..b7b09ea89904
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/contractCheck/UnknownIfCondition.java
@@ -0,0 +1,12 @@
+class Test {
+  
+  @org.jetbrains.annotations.Contract("null->false")
+  public static boolean smth(Object context) {
+    if (someMethodWithUnknownContract(context)) {
+      return true;
+    }
+    return false;
+  }
+
+  private static native boolean someMethodWithUnknownContract(Object o);
+}
\ No newline at end of file
diff --git a/java/java-tests/testSrc/com/intellij/codeInspection/ContractCheckTest.java b/java/java-tests/testSrc/com/intellij/codeInspection/ContractCheckTest.java
index 8d5eccab914c..2ec22019a95a 100644
--- a/java/java-tests/testSrc/com/intellij/codeInspection/ContractCheckTest.java
+++ b/java/java-tests/testSrc/com/intellij/codeInspection/ContractCheckTest.java
@@ -47,4 +47,5 @@ public class ContractCheckTest extends LightCodeInsightFixtureTestCase {
   public void testCheckConstructorContracts() { doTest(); }
 
   public void testPassingVarargsToDelegate() { doTest(); }
+  public void testUnknownIfCondition() { doTest(); }
 }