UnnecessaryBoxing: don't warn if inferred variable type will change (IDEA-193096)

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/migration/UnnecessaryBoxingInspection.java

@@ -250,6 +250,11 @@ public class UnnecessaryBoxingInspection extends BaseInspection {
           parent instanceof PsiSynchronizedStatement) {
         return true;
       }
+      else if (parent instanceof PsiVariable) {
+        PsiTypeElement typeElement = ((PsiVariable)parent).getTypeElement();
+        // Inferred type may change if boxing is removed; if it's possible
+        if (typeElement != null && typeElement.isInferredType()) return true;
+      }
       else if (parent instanceof PsiTypeCastExpression) {
         final PsiTypeCastExpression castExpression = (PsiTypeCastExpression)parent;
         return TypeUtils.isTypeParameter(castExpression.getType());

plugins/InspectionGadgets/test/com/siyeh/igtest/migration/unnecessary_boxing/UnnecessaryBoxing.java

@@ -135,4 +135,11 @@ class WithLambdaUnfriendlyOverloads {
       System.out.println("hello");
     }
   }
+
+  void testVar() {
+    var x = Integer.valueOf(5);
+    Integer y = <warning descr="Unnecessary boxing 'Integer.valueOf(5)'">Integer.valueOf(5)</warning>;
+    System.out.println(x.getClass());
+    System.out.println(y.getClass());
+  }
 }

plugins/InspectionGadgets/testsrc/com/siyeh/ig/migration/UnnecessaryBoxingInspectionTest.java

@@ -4,10 +4,17 @@
 package com.siyeh.ig.migration;
 
 import com.intellij.codeInspection.InspectionProfileEntry;
+import com.intellij.testFramework.LightProjectDescriptor;
 import com.siyeh.ig.LightInspectionTestCase;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 public class UnnecessaryBoxingInspectionTest extends LightInspectionTestCase {
+  @NotNull
+  @Override
+  protected LightProjectDescriptor getProjectDescriptor() {
+    return JAVA_10;
+  }
 
   public void testUnnecessaryBoxing() {
     doTest();