fix dfa contract believing that nullable is always null

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/StandardInstructionVisitor.java

@@ -245,7 +245,6 @@ public class StandardInstructionVisitor extends InstructionVisitor {
     DfaConstValue.Factory constFactory = factory.getConstFactory();
     List<DfaMemoryState> falseStates = ContainerUtil.newArrayList();
     for (int i = 0; i < argValues.length; i++) {
-      List<DfaMemoryState> nextStates = ContainerUtil.newArrayList();
       DfaValue argValue = argValues[i];
       MethodContract.ValueConstraint constraint = contract.arguments[i];
       DfaConstValue expectedValue = constraint == NULL_VALUE || constraint == NOT_NULL_VALUE ? constFactory.getNull() :
@@ -257,10 +256,14 @@ public class StandardInstructionVisitor extends InstructionVisitor {
       boolean invertCondition = constraint == NOT_NULL_VALUE;
       DfaValue condition = factory.getRelationFactory().createRelation(argValue, expectedValue, EQEQ, invertCondition);
       if (condition == null) {
-        if (!(argValue instanceof DfaConstValue)) continue;
+        if (!(argValue instanceof DfaConstValue)) {
+          falseStates.addAll(states);
+          continue;
+        }
         condition = constFactory.createFromValue(argValue == expectedValue, PsiType.BOOLEAN, null);
       }
 
+      List<DfaMemoryState> nextStates = ContainerUtil.newArrayList();
       for (DfaMemoryState state : states) {
         boolean unknownVsNull = expectedValue == constFactory.getNull() &&
                                 argValue instanceof DfaVariableValue &&

java/java-tests/testData/inspection/dataFlow/fixture/ContractInapplicableComparison.java

@@ -0,0 +1,16 @@
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.Nullable;
+
+class Foo {
+  void foo() {
+    Object o1 = bar(goo());
+    if (o1 == null) {
+      System.out.println();
+    }
+  }
+
+  @Nullable Object goo() { return null;}
+
+  @Nullable @Contract("null->null") static Object bar(@Nullable Object foo) { return foo; }
+
+}

java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTest.java

@@ -207,6 +207,7 @@ public class DataFlowInspectionTest extends LightCodeInsightFixtureTestCase {
   }
 
   public void testContractAnnotation() { doTest(); }
+  public void testContractInapplicableComparison() { doTest(); }
   public void testContractInLoopNotTooComplex() { doTest(); }
   public void testContractWithNullable() { doTest(); }
   public void testContractWithNotNull() { doTest(); }