IDEA-224476 False “May produce NullPointerException“ positive with Contract and method with parameters

GitOrigin-RevId: 0dddc582af0ac00cab70b2a237f11afa706477df

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

@@ -298,11 +298,16 @@ public abstract class ContractValue {
 
     @Override
     public DfaCallArguments updateArguments(DfaCallArguments arguments, boolean negated) {
+      DfaNullability targetNullability = DfaNullability.NOT_NULL;
       int index = getNullCheckedArgument(negated).orElse(-1);
+      if (index == -1) {
+        index = getNullCheckedArgument(!negated).orElse(-1);
+        targetNullability = DfaNullability.NULL;
+      }
       if (index >= 0 && index < arguments.myArguments.length) {
         DfaValue arg = arguments.myArguments[index];
         if (arg instanceof DfaFactMapValue) {
-          DfaValue newArg = ((DfaFactMapValue)arg).withFact(DfaFactType.NULLABILITY, DfaNullability.NOT_NULL);
+          DfaValue newArg = ((DfaFactMapValue)arg).withFact(DfaFactType.NULLABILITY, targetNullability);
           if (newArg != arg) {
             DfaValue[] newArguments = arguments.myArguments.clone();
             newArguments[index] = newArg;

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

@@ -0,0 +1,32 @@
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+class TestCls {
+  public String broken(@NotNull Getter dowGetter) {
+    final DayOfWeek dowOrDefault = firstNonNull(dowGetter.getDow(""), DayOfWeek.MONDAY);
+    return dowOrDefault.name();
+  }
+
+  public String correct(@NotNull Getter dowGetter) {
+    final DayOfWeek dowOrDefault = firstNonNull(dowGetter.getDow(), DayOfWeek.MONDAY);
+    return dowOrDefault.name();
+  }
+
+  @Nullable
+  @Contract(value = "!null, _ -> param1; null, !null -> param2; null, null -> null", pure = true)
+  public static <T> T firstNonNull(@Nullable T value1, @Nullable T value2) {
+    return value1 == null ? value2 : value1;
+  }
+
+  public interface Getter {
+    @Nullable
+    DayOfWeek getDow();
+    @Nullable
+    DayOfWeek getDow(String param);
+  }
+
+  enum DayOfWeek {
+    MONDAY
+  }
+}

java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java

@@ -251,6 +251,7 @@ public class DataFlowInspection8Test extends DataFlowInspectionTestCase {
   public void testLambdaWritesArrayInTry() { doTest(); }
   public void testManyNestedOptionals() { doTest(); }
   public void testGetClass() { doTest(); }
+  public void testParamContract() { doTest(); }
   public void testTypeUseVarArg() {
     setupTypeUseAnnotations("typeUse", myFixture);
     doTest();