[java-refactoring] Inline variable on non-initialized declaration

Could be available if there's only one write visible for all the reads
Fixes IDEA-354157 Inline variable not working when staying on uninitialized declaration

GitOrigin-RevId: e257b2b493a3902e901699efa4eac90f62e3108b

java/java-impl-refactorings/src/com/intellij/refactoring/inline/InlineLocalHandler.java

@@ -485,7 +485,23 @@ public final class InlineLocalHandler extends JavaInlineActionHandler {
         if (rExpr != null) return rExpr;
       }
     }
-    return local.getInitializer();
+    PsiExpression initializer = local.getInitializer();
+    if (initializer != null) {
+      return initializer;
+    }
+    List<PsiReferenceExpression> refs = VariableAccessUtils.getVariableReferences(local, block);
+    Set<PsiExpression> allDefs = new HashSet<>();
+    for (PsiReferenceExpression ref : refs) {
+      if (PsiUtil.isAccessedForWriting(ref)) {
+        if (PsiUtil.isAccessedForReading(ref)) return null;
+        continue;
+      }
+      PsiExpression def = getDefToInline(local, ref, block, rethrow);
+      if (def == null) return null;
+      allDefs.add(def);
+      if (allDefs.size() != 1) return null;
+    }
+    return ContainerUtil.getOnlyItem(allDefs);
   }
 
   @NotNull

java/java-tests/testData/refactoring/inlineLocal/SeparateInitialization.java

@@ -0,0 +1,7 @@
+public class Main {
+  public static void main(String[] args) {
+    String a<caret>aa;
+    aaa = args[0];
+    System.out.println(aaa);
+  }
+}

java/java-tests/testData/refactoring/inlineLocal/SeparateInitialization.java.after

@@ -0,0 +1,5 @@
+public class Main {
+  public static void main(String[] args) {
+      System.out.println(args[0]);
+  }
+}

java/java-tests/testData/refactoring/inlineLocal/SeparateInitialization2.java

@@ -0,0 +1,9 @@
+public class Main {
+  public static void main(String[] args) {
+    String a<caret>aa;
+    if (args.length > 0) {
+      aaa = args[0];
+      System.out.println(aaa);
+    }
+  }
+}

java/java-tests/testData/refactoring/inlineLocal/SeparateInitialization2.java.after

@@ -0,0 +1,7 @@
+public class Main {
+  public static void main(String[] args) {
+      if (args.length > 0) {
+          System.out.println(args[0]);
+    }
+  }
+}

java/java-tests/testData/refactoring/inlineLocal/SeparateInitialization3.java

@@ -0,0 +1,12 @@
+public class Main {
+  public static void main(String[] args) {
+    String a<caret>aa;
+    if (args.length > 0) {
+      aaa = args[0];
+      System.out.println(aaa);
+    } else {
+      aaa = "hello";
+      System.out.println(aaa);
+    }
+  }
+}

java/java-tests/testData/refactoring/inlineLocal/SeparateInitialization4.java

@@ -0,0 +1,11 @@
+public class Main {
+  public static void main(String[] args) {
+    String a<caret>aa;
+    if (args.length > 0) {
+      aaa = args[0];
+      System.out.println(aaa);
+    } else {
+      aaa = "oops";
+    }
+  }
+}

java/java-tests/testData/refactoring/inlineLocal/SeparateInitialization4.java.after

@@ -0,0 +1,10 @@
+public class Main {
+  public static void main(String[] args) {
+    String aaa;
+    if (args.length > 0) {
+        System.out.println(args[0]);
+    } else {
+      aaa = "oops";
+    }
+  }
+}

java/java-tests/testSrc/com/intellij/java/refactoring/inline/InlineLocalTest.java

@@ -359,6 +359,11 @@ public class InlineLocalTest extends LightJavaCodeInsightTestCase {
   
   public void testLambdaInitialization() { doTest(); }
   
+  public void testSeparateInitialization() { doTest(); }
+  public void testSeparateInitialization2() { doTest(); }
+  public void testSeparateInitialization3() { doTest("Cannot perform refactoring.\nVariable aaa has no initializer"); }
+  public void testSeparateInitialization4() { doTest(); }
+
   private void doTest(String conflictMessage) {
     try {
       doTest();