redundant cast: do not report redundant cast if dbl boxing/unboxing is prevented (IDEA-105323)

java/java-tests/testData/inspection/redundantCast/generics/BoxingInConditional/expected.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>Test.java</file>
+    <line>8</line>
+    <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant type cast</problem_class>
+    <description>Casting &lt;code&gt;2&lt;/code&gt; to &lt;code&gt;Integer&lt;/code&gt; is redundant</description>
+  </problem>
+</problems>

java/java-tests/testData/inspection/redundantCast/generics/BoxingInConditional/src/Test.java

@@ -0,0 +1,10 @@
+//This is a test for JDK_15 LanguageLevel
+public class Test {
+  private Integer foo(String s, Integer i) {
+    return s == null ? i : (Integer)2;
+  }
+
+  private int foo1(String s, Integer i) {
+    return s == null ? i : (Integer)2;
+  }
+}

java/java-tests/testSrc/com/intellij/codeInspection/RedundantCast15Test.java

@@ -24,6 +24,8 @@ public class RedundantCast15Test extends InspectionTestCase {
 
   public void testBoxingInRef() throws Exception { doTest(); }
 
+  public void testBoxingInConditional() throws Exception { doTest(); }
+
   public void testInference1() throws Exception { doTest(); }
 
   public void testInference2() throws Exception { doTest(); }

java/openapi/src/com/intellij/psi/util/RedundantCastUtil.java

@@ -383,7 +383,9 @@ public class RedundantCastUtil {
         PsiElement parent = typeCast.getParent();
         if (parent instanceof PsiConditionalExpression) {
           //branches need to be of the same type
-          if (!Comparing.equal(operand.getType(), ((PsiConditionalExpression)parent).getType())) {
+          final PsiType operandType = operand.getType();
+          final PsiType conditionalType = ((PsiConditionalExpression)parent).getType();
+          if (!Comparing.equal(operandType, conditionalType)) {
             if (!PsiUtil.isLanguageLevel5OrHigher(typeCast)) {
               return;
             }
@@ -578,6 +580,12 @@ public class RedundantCastUtil {
       if (firstOperand != null && otherOperand != null && wrapperCastChangeSemantics(firstOperand, otherOperand, operand)) {
         return true;
       }
+    } else if (parent instanceof PsiConditionalExpression) {
+      if (opType instanceof PsiPrimitiveType && !(((PsiConditionalExpression)parent).getType() instanceof PsiPrimitiveType)) {
+        if (PsiPrimitiveType.getUnboxedType(PsiTypesUtil.getExpectedTypeByParent((PsiExpression)parent)) != null) {
+          return true;
+        }
+      }
     }
     return false;
   }