From 2448cc73ceaac84d4ee5d445a0e9c953750e9b12 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Fournier?= <clement.fournier76@gmail.com>
Date: Sat, 20 Jun 2020 02:27:10 +0200
Subject: [PATCH] Handle break

---
 .../rule/errorprone/UnusedAssignmentRule.java |  12 +++
 .../rule/errorprone/xml/UnusedAssignment.xml  | 101 +++++++++++++++++-
 2 files changed, 112 insertions(+), 1 deletion(-)

diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/errorprone/UnusedAssignmentRule.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/errorprone/UnusedAssignmentRule.java
index 9b09d66f56..7f1f021d60 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/errorprone/UnusedAssignmentRule.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/errorprone/UnusedAssignmentRule.java
@@ -15,6 +15,7 @@ import java.util.Objects;
 import java.util.Set;
 
 import net.sourceforge.pmd.lang.java.ast.ASTAssignmentOperator;
+import net.sourceforge.pmd.lang.java.ast.ASTBreakStatement;
 import net.sourceforge.pmd.lang.java.ast.ASTExpression;
 import net.sourceforge.pmd.lang.java.ast.ASTIfStatement;
 import net.sourceforge.pmd.lang.java.ast.ASTMethodDeclaration;
@@ -127,6 +128,12 @@ public class UnusedAssignmentRule extends AbstractJavaRule {
             return ((ScopeData) data).abruptCompletion();
         }
 
+        @Override
+        public Object visit(ASTBreakStatement node, Object data) {
+            data = super.visit(node, data);
+            return ((ScopeData) data).abruptCompletion();
+        }
+
         @Override
         public Object visit(ASTReturnStatement node, Object data) {
             data = super.visit(node, data);
@@ -169,6 +176,11 @@ public class UnusedAssignmentRule extends AbstractJavaRule {
 
                 VariableNameDeclaration lhsVar = getLhsVar(node.getChild(0), true);
                 if (lhsVar != null) {
+                    if (node.getChild(1).getImage().length() >= 2) {
+                        // compound assignment, to use BEFORE assigning
+                        ((ScopeData) data).use(lhsVar);
+                    }
+
                     ((ScopeData) data).assign(lhsVar, rhs);
                 } else {
                     node.getChild(0).jjtAccept(this, data);
diff --git a/pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/errorprone/xml/UnusedAssignment.xml b/pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/errorprone/xml/UnusedAssignment.xml
index b47fb98624..1bc4f5eec3 100644
--- a/pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/errorprone/xml/UnusedAssignment.xml
+++ b/pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/errorprone/xml/UnusedAssignment.xml
@@ -293,7 +293,7 @@ class Test{
     </test-code>
 
     <test-code>
-        <description>#1905 [java] DataflowAnomalyAnalysis Rule in right order : Case 4. DU-Anomaly(a)</description>
+        <description>While loop 1</description>
         <expected-problems>0</expected-problems>
         <code><![CDATA[
 class Test{
@@ -309,6 +309,105 @@ class Test{
         ]]></code>
     </test-code>
 
+    <test-code>
+        <description>While loop 2</description>
+        <expected-problems>2</expected-problems>
+        <expected-linenumbers>4,7</expected-linenumbers>
+        <expected-messages>
+            <message>The value assigned to variable 'i' is never used</message>
+            <message>The value assigned to variable 'i' is never used</message>
+        </expected-messages>
+        <code><![CDATA[
+class Test{
+    public static void main(String[] args){
+        int a = 0;
+        int i = 0; // unused
+        while(a < 30){
+            a = a + 3;
+            i = 5; // unused (kills itself)
+        }
+    }
+}
+        ]]></code>
+    </test-code>
+    <test-code>
+        <description>While loop with break</description>
+        <expected-problems>1</expected-problems>
+        <expected-linenumbers>7</expected-linenumbers>
+        <expected-messages>
+            <message>The value assigned to variable 'i' is never used</message>
+        </expected-messages>
+        <code><![CDATA[
+class Test{
+    public static void main(String[] args){
+        int a = 0;
+        int i = 0;
+        while (true) {
+            if (a >= 30) {
+                i = a + 1; // unused
+                break;
+            }
+            a = a + 3;
+            i = i + 1; // used by itself
+        }
+    }
+}
+        ]]></code>
+    </test-code>
+    <test-code>
+        <description>While loop without break (control case)</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+class Test{
+    public static void main(String[] args){
+        int a = 0;
+        int i = 0;
+        while (true) {
+            if (a >= 30) {
+                i = a + 1; // used by below
+                // break;  // no break here
+            }
+            a = a + 3;
+            i = i + 1; // used by itself
+        }
+    }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>While loop with break 2</description>
+        <expected-problems>1</expected-problems>
+        <expected-linenumbers>12</expected-linenumbers>
+        <expected-messages>
+            <message>The value assigned to variable 'i' is never used</message>
+        </expected-messages>
+        <code><![CDATA[
+class Test{
+    public static void main(String[] args){
+        int a = 0;
+        int i = 0; // used now
+
+        outer:
+        while (true) {
+            a += 2;
+
+            while (true) {
+                if (a >= 30) {
+                    i = i + 1; // used now
+                    break outer;
+                }
+                a = a + 3;
+                i = i + 2; // unused (kills itself)
+            }
+        }
+
+        System.out.println(i); // uses i = i + 1
+    }
+}
+        ]]></code>
+    </test-code>
+
     <test-code>
         <description>#1905 [java] DataflowAnomalyAnalysis Rule in right order : Case 5. DU-Anomaly(a)</description>
         <expected-problems>1</expected-problems>