NullnessUtil#getExpressionNullness: useDataflow argument

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

@@ -122,6 +122,18 @@ public class NullnessUtil {
   }
 
   public static Nullness getExpressionNullness(@Nullable PsiExpression expression) {
+    return getExpressionNullness(expression, false);
+  }
+
+  /**
+   * Tries to determine an expression nullness
+   *
+   * @param expression an expression to check
+   * @param useDataflow whether to use dataflow (more expensive, but may produce more precise result)
+   * @return expression nullness. UNKNOWN if unable to determine;
+   * NULLABLE if known to possibly have null value; NOT_NULL if definitely never null.
+   */
+  public static Nullness getExpressionNullness(@Nullable PsiExpression expression, boolean useDataflow) {
     expression = PsiUtil.skipParenthesizedExprDown(expression);
     if (expression == null) return Nullness.UNKNOWN;
     if (expression.textMatches(PsiKeyword.NULL)) return Nullness.NULLABLE;
@@ -136,13 +148,13 @@ public class NullnessUtil {
       PsiExpression thenExpression = ((PsiConditionalExpression)expression).getThenExpression();
       PsiExpression elseExpression = ((PsiConditionalExpression)expression).getElseExpression();
       if (thenExpression == null || elseExpression == null) return Nullness.UNKNOWN;
-      Nullness left = getExpressionNullness(thenExpression);
+      Nullness left = getExpressionNullness(thenExpression, useDataflow);
       if (left == Nullness.UNKNOWN) return Nullness.UNKNOWN;
-      Nullness right = getExpressionNullness(elseExpression);
+      Nullness right = getExpressionNullness(elseExpression, useDataflow);
       return left == right ? left : Nullness.UNKNOWN;
     }
     if (expression instanceof PsiTypeCastExpression) {
-      return getExpressionNullness(((PsiTypeCastExpression)expression).getOperand());
+      return getExpressionNullness(((PsiTypeCastExpression)expression).getOperand(), useDataflow);
     }
     if (expression instanceof PsiReferenceExpression) {
       PsiElement target = ((PsiReferenceExpression)expression).resolve();
@@ -151,10 +163,13 @@ public class NullnessUtil {
     if (expression instanceof PsiAssignmentExpression) {
       PsiAssignmentExpression assignment = (PsiAssignmentExpression)expression;
       if(assignment.getOperationTokenType().equals(JavaTokenType.EQ)) {
-        return getExpressionNullness(assignment.getRExpression());
+        return getExpressionNullness(assignment.getRExpression(), useDataflow);
       }
       return Nullness.NOT_NULL;
     }
+    if (useDataflow) {
+      return fromBoolean(CommonDataflow.getExpressionFact(expression, DfaFactType.CAN_BE_NULL));
+    }
     if (expression instanceof PsiMethodCallExpression) {
       PsiMethod method = ((PsiMethodCallExpression)expression).resolveMethod();
       return method != null ? DfaPsiUtil.getElementNullability(expression.getType(), method) : Nullness.UNKNOWN;

java/java-impl/src/com/intellij/codeInsight/template/postfix/templates/OptionalPostfixTemplate.java

@@ -51,7 +51,7 @@ public class OptionalPostfixTemplate extends StringBasedPostfixTemplate {
       }
     }
 
-    String methodName = Nullness.NOT_NULL.equals(NullnessUtil.getExpressionNullness((PsiExpression)element)) ? "of" : "ofNullable";
+    String methodName = Nullness.NOT_NULL.equals(NullnessUtil.getExpressionNullness((PsiExpression)element, true)) ? "of" : "ofNullable";
     return "java.util." + className + "." + methodName + "($expr$)";
   }
 }

java/java-impl/src/com/intellij/codeInspection/OptionalIsPresentInspection.java

@@ -186,7 +186,7 @@ public class OptionalIsPresentInspection extends AbstractBaseJavaLocalInspection
     if (!hasNoBadRefs) return ProblemType.NONE;
     if (!hasOptionalReference.get() || !(lambdaCandidate instanceof PsiExpression)) return ProblemType.INFO;
     PsiExpression expression = (PsiExpression)lambdaCandidate;
-    if (falseExpression != null && NullnessUtil.getExpressionNullness(expression) != Nullness.NOT_NULL) {
+    if (falseExpression != null && NullnessUtil.getExpressionNullness(expression, true) != Nullness.NOT_NULL) {
       // falseExpression == null is "consumer" case (to be replaced with ifPresent()),
       // in this case we don't care about expression nullness
       return ProblemType.INFO;

java/java-impl/src/com/intellij/codeInspection/ReplaceNullCheckInspection.java

@@ -292,7 +292,7 @@ public class ReplaceNullCheckInspection extends AbstractBaseJavaLocalInspectionT
         nonNullDiff = qualifierDiff.getRight();
         if(!ExpressionUtils.isReferenceTo(nullDiff, variable)) return null;
       }
-      if(NullnessUtil.getExpressionNullness(nonNullDiff) != Nullness.NOT_NULL) return null;
+      if(NullnessUtil.getExpressionNullness(nonNullDiff, true) != Nullness.NOT_NULL) return null;
       if(!LambdaGenerationUtil.canBeUncheckedLambda(nonNullDiff)) return null;
       return new NotNullContext(nonNullDiff, nullDiff, nullBranch, variable, ifStatement, toDelete, false);
     }
@@ -355,7 +355,7 @@ public class ReplaceNullCheckInspection extends AbstractBaseJavaLocalInspectionT
       if(ClassUtils.isPrimitive(variable.getType())) return null;
       PsiExpression nullBranch = negated ? ternary.getThenExpression() : ternary.getElseExpression();
       if(!ExpressionUtils.isReferenceTo(nullBranch, variable)) return null;
-      if(NullnessUtil.getExpressionNullness(nonNullBranch) != Nullness.NOT_NULL) return null;
+      if(NullnessUtil.getExpressionNullness(nonNullBranch, true) != Nullness.NOT_NULL) return null;
       if(!LambdaGenerationUtil.canBeUncheckedLambda(nonNullBranch)) return null;
       return new TernaryNotNullContext(ternary, nonNullBranch, variable);
     }