Fix final variable definition that is used in a for loop being moved outside the for loop

src/org/jetbrains/java/decompiler/modules/decompiler/MergeHelper.java

@@ -433,6 +433,12 @@ protected static void matchFor(DoStatement stat) {
         return;
       }
 
+      // Check if any final variable assignments in the loop are used in the line that is being moved to the final part of the for loop
+      Set<VarExprent> finalVariables = getFinalVariables(stat, new HashSet<>());
+      if (finalVariables.stream().anyMatch(exp -> exp.isVarReferenced(lastExp))) {
+        return;
+      }
+
       stat.setLooptype(DoStatement.Type.FOR);
       if (hasinit) {
         Exprent exp = preData.getExprents().remove(preData.getExprents().size() - 1);
@@ -451,6 +457,38 @@ protected static void matchFor(DoStatement stat) {
     cleanEmptyStatements(stat, lastData);
   }
 
+  private static Set<VarExprent> getFinalVariables(Statement stat, Set<VarExprent> variables) {
+    if (stat.getExprents() == null) {
+      for (Object o : stat.getSequentialObjects()) {
+        if (o instanceof Statement) {
+          getFinalVariables((Statement) o, variables);
+        } else if (o instanceof Exprent) {
+          getFinalVariables((Exprent) o, variables);
+        }
+      }
+    } else {
+      for (Exprent exp : stat.getExprents()) {
+        getFinalVariables(exp, variables);
+      }
+    }
+    return variables;
+  }
+
+  private static Set<VarExprent> getFinalVariables(Exprent exp, Set<VarExprent> variables) {
+    for (Exprent e : exp.getAllExprents(true, true)) {
+      if (e instanceof AssignmentExprent) {
+        AssignmentExprent assignment = (AssignmentExprent) e;
+        if (assignment.getLeft() instanceof VarExprent) {
+          VarExprent varExprent = (VarExprent) assignment.getLeft();
+          if (varExprent.isEffectivelyFinal()) {
+            variables.add(varExprent);
+          }
+        }
+      }
+    }
+    return variables;
+  }
+
   protected static void cleanEmptyStatements(DoStatement dostat, Statement stat) {
     if (stat != null && stat.getExprents().isEmpty()) {
       List<StatEdge> lst = stat.getAllSuccessorEdges();

test/org/jetbrains/java/decompiler/SingleClassesTest.java

@@ -672,6 +672,7 @@ private void registerDefault() {
     register(JAVA_16, "TestIfPatternMatchMethod");
     // TODO: Param type information is lost for lambdas where a more specific type is not required by the context
     register(JAVA_8, "TestLambdaParamTypes");
+    register(JAVA_8, "TestWhileLambda");
   }
 
   private void registerEntireClassPath() {

testData/results/pkg/TestWhileLambda.dec

@@ -0,0 +1,39 @@
+package pkg;
+
+import java.util.function.Supplier;
+
+public class TestWhileLambda {
+   public void test() {
+      Object o = new Object();// 7
+
+      while (o != null) {// 8
+         Object o2 = new Object();// 9
+         Supplier var3 = () -> o2;// 10
+      }
+   }// 12
+}
+
+class 'pkg/TestWhileLambda' {
+   method 'test ()V' {
+      7      6
+      8      8
+      9      8
+      13      9
+      1a      10
+      1e      12
+   }
+
+   method 'lambda$test$0 (Ljava/lang/Object;)Ljava/lang/Object;' {
+      0      10
+      1      10
+   }
+}
+
+Lines mapping:
+7 <-> 7
+8 <-> 9
+9 <-> 10
+10 <-> 11
+12 <-> 13
+Not mapped:
+11

testData/src/java8/pkg/TestWhileLambda.java

@@ -0,0 +1,13 @@
+package pkg;
+
+import java.util.function.Supplier;
+
+public class TestWhileLambda {
+    public void test() {
+        Object o = new Object();
+        while (o != null) {
+            Object o2 = new Object();
+            Supplier<Object> s = () -> o2;
+        }
+    }
+}