SONARJAVA-5096 S1764: FP on expressions with side-effects (#4878)

SonarSource · Sep 23, 2024 · d709152 · d709152
1 parent 8333a7d
commit d709152
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Showing 3 changed files with 16 additions and 3 deletions.
diff --git a/...-checks-test-sources/default/src/main/java/checks/IdenticalOperandOnBinaryExpression.java b/...-checks-test-sources/default/src/main/java/checks/IdenticalOperandOnBinaryExpression.java
@@ -1,5 +1,7 @@
 package checks;
 
+import java.util.Random;
+
 class IdenticalOperandOnBinaryExpressionCheck {
   void foo(boolean a, boolean b, boolean c, boolean e) {
     if(a == b) { }
@@ -41,4 +43,16 @@ void fun(Object a, Object b) {
     java.util.Objects.deepEquals(a, b);
     java.util.Objects.isNull(a);
   }
+
+  void sonarJava5096() {
+    Random r = new Random();
+    var a = r.nextBoolean() && r.nextBoolean(); // Compliant
+    var b = foo() - foo(); // Compliant
+    var c = (foo()) - (foo()); // Compliant
+    var d = (3 + foo() * 4) - (3 + foo() * 4); // Compliant
+  }
+
+  int foo() {
+    return 42;
+  }
 }
diff --git a/java-checks/src/main/java/org/sonar/java/checks/IdenticalOperandOnBinaryExpressionCheck.java b/java-checks/src/main/java/org/sonar/java/checks/IdenticalOperandOnBinaryExpressionCheck.java
@@ -145,7 +145,7 @@ public static ExpressionTree equivalentOperand(BinaryExpressionTree tree, Expres
   }
 
   public static ExpressionTree equivalentOperand(ExpressionTree left, ExpressionTree right, Tree.Kind binaryKind) {
-    if (SyntacticEquivalence.areEquivalent(left, right)) {
+    if (SyntacticEquivalence.areEquivalent(left, right, (t1, t2) -> t1.is(Tree.Kind.METHOD_INVOCATION), false)) {
       return left;
     }
     // Check other operands if operator is symmetric.

diff --git a/java-frontend/src/main/java/org/sonar/java/model/SyntacticEquivalence.java b/java-frontend/src/main/java/org/sonar/java/model/SyntacticEquivalence.java
@@ -96,8 +96,7 @@ private static boolean areEquivalent(List<? extends Tree> leftList,
     return true;
   }
 
-  @VisibleForTesting
-  static boolean areEquivalent(@Nullable Tree leftNode, @Nullable Tree rightNode, BiPredicate<JavaTree, JavaTree> overwriteEquivalence, boolean equivalenceValue) {
+  public static boolean areEquivalent(@Nullable Tree leftNode, @Nullable Tree rightNode, BiPredicate<JavaTree, JavaTree> overwriteEquivalence, boolean equivalenceValue) {
     return areEquivalent((JavaTree) leftNode, (JavaTree) rightNode, overwriteEquivalence, equivalenceValue);
   }