[java-intentions] PsiElementFactoryImpl.createVariableDeclarationStatement: use 'var' if non-denotable type is requested

Fixes IDEA-374601 Copy 'x' to effectively final variable breaks code when type is non-denotable

GitOrigin-RevId: 3b2d15f24b182ac3948ae3b5066c5e68c1c0bf5c

java/java-psi-impl/src/com/intellij/psi/impl/PsiElementFactoryImpl.java

@@ -23,6 +23,7 @@ import com.intellij.psi.impl.source.tree.TreeElement;
 import com.intellij.psi.javadoc.PsiDocTag;
 import com.intellij.psi.search.GlobalSearchScope;
 import com.intellij.psi.tree.IElementType;
+import com.intellij.psi.util.PsiTypesUtil;
 import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.ConcurrencyUtil;
 import com.intellij.util.IncorrectOperationException;
@@ -592,11 +593,15 @@ public final class PsiElementFactoryImpl extends PsiJavaParserFacadeImpl impleme
       throw new IncorrectOperationException("Cannot create variable with type \"null\".");
     }
 
-    String text = "X " + name + (initializer != null ? " = x" : "") + ";";
+    String text = "var " + name + (initializer != null ? " = x" : "") + ";";
     PsiDeclarationStatement statement = (PsiDeclarationStatement)createStatementFromText(text, context);
 
     PsiVariable variable = (PsiVariable)statement.getDeclaredElements()[0];
-    replace(variable.getTypeElement(), createTypeElement(GenericsUtil.getVariableTypeByExpressionType(type)), text);
+    boolean generateVar = !PsiTypesUtil.isDenotableType(type, variable) && initializer != null &&
+                PsiUtil.isAvailable(JavaFeature.LVTI, initializer);
+    if (!generateVar) {
+      replace(variable.getTypeElement(), createTypeElement(GenericsUtil.getVariableTypeByExpressionType(type)), text);
+    }
 
     boolean generateFinalLocals =
       context != null && JavaFileCodeStyleFacade.forContext(context.getContainingFile()).isGenerateFinalLocals();

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/mustBeFinalJava10/afterIfVarNonDenotable2.java

@@ -0,0 +1,18 @@
+// "Copy 'x' to effectively final temp variable" "true-preview"
+class Abc {
+  interface A{}
+  interface B{
+    void m();
+  }
+
+  void test(Object obj) {
+    var x = (A & B) obj;
+    if (Math.random() > 0.5) {
+      x = null;
+    }
+      var finalX = x;
+      Runnable r = () -> {
+      if (finalX != null) finalX.m();
+    };
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/mustBeFinalJava10/beforeIfVarNonDenotable2.java

@@ -0,0 +1,17 @@
+// "Copy 'x' to effectively final temp variable" "true-preview"
+class Abc {
+  interface A{}
+  interface B{
+    void m();
+  }
+
+  void test(Object obj) {
+    var x = (A & B) obj;
+    if (Math.random() > 0.5) {
+      x = null;
+    }
+    Runnable r = () -> {
+      if (<caret>x != null) x.m();
+    };
+  }
+}

java/java-tests/testData/ig/com/siyeh/igfixes/style/methodRefs2lambda/afterIntroduceVariableForSideEffectQualifier.java

@@ -1,7 +1,7 @@
 // "Replace method reference with lambda" "true-preview"
 class Test {
   {
-      Runnable runnable1 = new Runnable() {
+      var runnable1 = new Runnable() {
           {
           }