[extract method] fix: don't declare variable twice

GitOrigin-RevId: a7b8bcccb1e4bf4fb5ea35975f12767dae882813

java/java-impl/src/com/intellij/refactoring/extractMethod/newImpl/ExtractMethodAnalyzer.kt

@@ -74,7 +74,8 @@ fun findExtractOptions(elements: List<PsiElement>): ExtractOptions {
     .map { it.copy(type = normalizeType(it.type)) }
   val parameterNames = inputParameters.map { it.name }.toSet()
 
-  val exposedVariables = analyzer.findExposedLocalDeclarations()
+  val outputVariable = (dataOutput as? VariableOutput)?.variable
+  val exposedVariables = analyzer.findExposedLocalDeclarations().filter { exposedVariable -> exposedVariable != outputVariable }
 
   extractOptions = extractOptions.copy(
     dataOutput = normalizeDataOutput(dataOutput, flowOutput, elements, exposedVariables.mapNotNull { it.name }),

java/java-tests/testData/refactoring/extractMethodAndDuplicatesInplace/ChangedVariableDeclaredOnce.java

@@ -0,0 +1,7 @@
+public class Test {
+    void test(boolean condition) {
+        <selection>String s = "42";</selection>
+        if (condition) s = "new";
+        System.out.println(s);
+    }
+}

java/java-tests/testData/refactoring/extractMethodAndDuplicatesInplace/ChangedVariableDeclaredOnce_after.java

@@ -0,0 +1,15 @@
+import org.jetbrains.annotations.NotNull;
+
+public class Test {
+    void test(boolean condition) {
+        String s = getString();
+        if (condition) s = "new";
+        System.out.println(s);
+    }
+
+    @NotNull
+    private String getString() {
+        String s = "42";
+        return s;
+    }
+}

java/java-tests/testSrc/com/intellij/java/refactoring/ExtractMethodAndDuplicatesInplaceTest.kt

@@ -202,6 +202,10 @@ class ExtractMethodAndDuplicatesInplaceTest: LightJavaCodeInsightTestCase() {
     doTest()
   }
 
+  fun testChangedVariableDeclaredOnce(){
+    doTest()
+  }
+
   fun testRefactoringListener(){
     templateTest {
       configureByFile("$BASE_PATH/${getTestName(false)}.java")