ExplicitArrayFillingInspection: suggest Arrays.fill in cases when filled value is immutable (IDEA-CR-50510)

GitOrigin-RevId: a9d5627d25572edeb2f920aff62d108dd6f183ac

java/java-impl/src/com/intellij/codeInspection/ExplicitArrayFillingInspection.java

@@ -13,7 +13,6 @@ import com.intellij.profile.codeInspection.InspectionProjectProfileManager;
 import com.intellij.psi.*;
 import com.intellij.psi.codeStyle.CodeStyleManager;
 import com.intellij.psi.codeStyle.JavaCodeStyleManager;
-import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiTypesUtil;
 import com.intellij.util.ObjectUtils;
 import com.siyeh.ig.psiutils.*;
@@ -73,9 +72,13 @@ public class ExplicitArrayFillingInspection extends AbstractBaseJavaLocalInspect
       }
 
       private boolean isChangedInLoop(@NotNull CountingLoop loop, @NotNull PsiExpression rValue) {
-        return VariableAccessUtils.collectUsedVariables(rValue).contains(loop.getCounter()) ||
-               SideEffectChecker.mayHaveSideEffects(rValue) ||
-               PsiTreeUtil.findChildOfType(rValue, PsiNewExpression.class, false) != null;
+        if (VariableAccessUtils.collectUsedVariables(rValue).contains(loop.getCounter()) ||
+            SideEffectChecker.mayHaveSideEffects(rValue)) {
+          return true;
+        }
+        return ExpressionUtils.nonStructuralChildren(rValue)
+          .filter(c -> c instanceof PsiCallExpression)
+          .anyMatch(call -> !ClassUtils.isImmutable(call.getType()) && !ConstructionUtils.isEmptyArrayInitializer(call));
       }
 
       private void registerProblem(@NotNull PsiForStatement statement, boolean isSetAll) {

java/java-tests/testData/inspection/explicitArrayFilling/afterEmptyArrayCreation.java

@@ -0,0 +1,13 @@
+// "Replace loop with 'Arrays.fill()' method call" "true"
+
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Arrays;
+
+class Test {
+  private void test2() {
+    int[][] arr = new int[10][];
+      Arrays.fill(arr, new int[0]);
+  }
+}

java/java-tests/testData/inspection/explicitArrayFilling/afterImmutableObjectFromMethod.java

@@ -0,0 +1,15 @@
+// "Replace loop with 'Arrays.fill()' method call" "true"
+
+import java.util.Arrays;
+
+class Test {
+
+  void test() {
+    final String[] arr = new String[2];
+      Arrays.fill(arr, getString());
+  }
+
+  private static String getString() {
+    return "foo";
+  }
+}

java/java-tests/testData/inspection/explicitArrayFilling/afterSuppliersArray.java

@@ -0,0 +1,12 @@
+// "Replace loop with 'Arrays.fill()' method call" "true"
+
+import java.util.Arrays;
+
+class Test {
+
+  private void testLambdas() {
+    Supplier[] arr = new Supplier[10];
+      Arrays.fill(arr, () -> new int[10]);
+  }
+
+}

java/java-tests/testData/inspection/explicitArrayFilling/afterTernaryWithMutable.java

@@ -0,0 +1,12 @@
+// "Replace loop with 'Arrays.setAll()' method call" "true"
+
+import java.util.Arrays;
+
+class Test {
+
+  void test(boolean choice) {
+    Object[] arr = new Object[10];
+      Arrays.setAll(arr, i -> (choice ? "foo" : new Object()));
+  }
+
+}

java/java-tests/testData/inspection/explicitArrayFilling/beforeEmptyArrayCreation.java

@@ -0,0 +1,13 @@
+// "Replace loop with 'Arrays.fill()' method call" "true"
+
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+
+class Test {
+  private void test2() {
+    int[][] arr = new int[10][];
+    for (<caret>int i = 0; i < arr.length; i++) {
+      arr[i] = new int[0];
+    }
+  }
+}

java/java-tests/testData/inspection/explicitArrayFilling/beforeImmutableObjectFromMethod.java

@@ -0,0 +1,15 @@
+// "Replace loop with 'Arrays.fill()' method call" "true"
+
+class Test {
+
+  void test() {
+    final String[] arr = new String[2];
+    for (<caret>int i = 0; i < arr.length; i++) {
+      arr[i] = getString();
+    }
+  }
+
+  private static String getString() {
+    return "foo";
+  }
+}

java/java-tests/testData/inspection/explicitArrayFilling/beforeSuppliersArray.java

@@ -0,0 +1,12 @@
+// "Replace loop with 'Arrays.fill()' method call" "true"
+
+class Test {
+
+  private void testLambdas() {
+    Supplier[] arr = new Supplier[10];
+    for (<caret>int i = 0; i < arr.length; i++) {
+      arr[i] = () -> new int[10];
+    }
+  }
+
+}

java/java-tests/testData/inspection/explicitArrayFilling/beforeTernaryWithMutable.java

@@ -0,0 +1,12 @@
+// "Replace loop with 'Arrays.setAll()' method call" "true"
+
+class Test {
+
+  void test(boolean choice) {
+    Object[] arr = new Object[10];
+    for (<caret>int i = 0; i < arr.length; i++) {
+      arr[i] = (choice ? "foo" : new Object());
+    }
+  }
+
+}