IDEA-230889 'Object allocation in a loop' doesn't detect concatenation of two constant Strings inside the loop

GitOrigin-RevId: 0952486abeb99ba108af82028dce126d01a8fcfa

plugins/InspectionGadgets/InspectionGadgetsAnalysis/resources/messages/InspectionGadgetsBundle.properties

@@ -1029,6 +1029,7 @@ object.allocation.in.loop.new.descriptor=Object allocation <code>new #ref()</cod
 object.allocation.in.loop.problem.call.descriptor=Object allocation via <code>#ref()</code> call in loop #loc
 object.allocation.in.loop.problem.methodref.descriptor=Object allocation via instance-bound method reference <code>#ref()</code> in loop #loc
 object.allocation.in.loop.problem.lambda.descriptor=Object allocation via capturing lambda in loop #loc
+object.allocation.in.loop.problem.string.concat=Object allocation via string concatenation in loop #loc
 instantiating.object.to.get.class.object.problem.descriptor=Instantiating object to get Class object #loc
 field.may.be.static.problem.descriptor=Field <code>#ref</code> may be 'static' #loc
 method.may.be.static.problem.descriptor=Method <code>#ref()</code> may be 'static' #loc

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/performance/ObjectAllocationInLoopInspection.java

@@ -22,12 +22,15 @@ import com.intellij.codeInspection.dataFlow.JavaMethodContractUtil;
 import com.intellij.codeInspection.dataFlow.NullabilityUtil;
 import com.intellij.codeInspection.dataFlow.StandardMethodContract;
 import com.intellij.psi.*;
+import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
+import com.intellij.psi.util.PsiUtil;
 import com.siyeh.InspectionGadgetsBundle;
 import com.siyeh.ig.BaseInspection;
 import com.siyeh.ig.BaseInspectionVisitor;
 import com.siyeh.ig.psiutils.ControlFlowUtils;
 import com.siyeh.ig.psiutils.ExpressionUtils;
+import com.siyeh.ig.psiutils.TypeUtils;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.PropertyKey;
 
@@ -40,7 +43,8 @@ public class ObjectAllocationInLoopInspection extends BaseInspection {
     NEW_OPERATOR("object.allocation.in.loop.new.descriptor"),
     METHOD_CALL("object.allocation.in.loop.problem.call.descriptor"),
     METHOD_REFERENCE("object.allocation.in.loop.problem.methodref.descriptor"),
-    CAPTURING_LAMBDA("object.allocation.in.loop.problem.lambda.descriptor");
+    CAPTURING_LAMBDA("object.allocation.in.loop.problem.lambda.descriptor"),
+    STRING_CONCAT("object.allocation.in.loop.problem.string.concat");
 
     private final String myMessage;
 
@@ -105,6 +109,16 @@ public class ObjectAllocationInLoopInspection extends BaseInspection {
       }
     }
 
+    @Override
+    public void visitPolyadicExpression(PsiPolyadicExpression expression) {
+      IElementType type = expression.getOperationTokenType();
+      if (JavaTokenType.PLUS.equals(type) && TypeUtils.isJavaLangString(expression.getType()) &&
+          !PsiUtil.isConstantExpression(expression) && isPerformedRepeatedlyInLoop(expression)) {
+        registerError(expression, Kind.STRING_CONCAT);
+      }
+      super.visitPolyadicExpression(expression);
+    }
+
     private static boolean isPerformedRepeatedlyInLoop(@NotNull PsiExpression expression) {
       if (!ControlFlowUtils.isInLoop(expression)) return false;
       if (ControlFlowUtils.isInExitStatement(expression)) return false;

plugins/InspectionGadgets/test/com/siyeh/igtest/performance/object_allocation_in_loop/ObjectAllocationInLoop.java

@@ -87,4 +87,15 @@ class ObjectAllocationInLoop {
   }
 
   static native Integer key();
+
+  final int CONST = 10;
+  
+  void concat() {
+    for (int i = 0; i < 10; i++) {
+      String s = <warning descr="Object allocation via string concatenation in loop">"value: " + i</warning>;
+      String s2 = "value: " + CONST;
+      System.out.println(s);
+      System.out.println(s2);
+    }
+  }
 }