Fix for loop overflowing the stack. Fixes #122

resources/bytecode/javFiles/Bug122.jav

@@ -0,0 +1,12 @@
+import java.lang.Integer;
+import java.lang.Boolean;
+
+class Bug122 {
+    void main() {
+        if (true) {
+            for (Integer i = 0; i < 10; i++) {
+
+            }
+        }
+    }
+}

src/main/java/de/dhbwstuttgart/bytecode/Codegen.java

@@ -886,8 +886,12 @@ public class Codegen {
         case TargetFor _for: {
             state.enterScope();
             var localCounter = state.localCounter;
-            if (_for.init() != null)
-                _for.init().forEach(e -> generate(state, e));
+            if (_for.init() != null) {
+                for (var e : _for.init()) {
+                    generate(state, e);
+                    if (e instanceof TargetAssign) mv.visitInsn(POP);
+                }
+            }
 
             Label start = new Label();
             Label end = new Label();

src/main/java/de/dhbwstuttgart/parser/SyntaxTreeGenerator/StatementGenerator.java

@@ -513,8 +513,9 @@ public class StatementGenerator {
         } else {
             return new ForStmt(
                 stmt.getStart(),
-                convert(control.forInit().localVariableDeclaration()),
-                convert(control.expression()), control.forUpdate.expression().stream().map(this::convert).toList(),
+                control.forInit() != null ? convert(control.forInit().localVariableDeclaration()) : List.of(),
+                control.expression() != null ? convert(control.expression()) : null,
+                control.forUpdate != null ? control.forUpdate.expression().stream().map(this::convert).toList() : List.of(),
                 convert(stmt.statement())
             );
         }

src/main/java/de/dhbwstuttgart/target/generate/StatementToTargetExpression.java

@@ -141,7 +141,12 @@ public class StatementToTargetExpression implements ASTVisitor {
 
     @Override
     public void visit(ForStmt forStmt) {
-        result = new TargetFor(forStmt.initializer.stream().map(converter::convert).toList(), converter.convert(forStmt.condition), forStmt.loopExpr.stream().map(converter::convert).toList(), converter.convert(forStmt.block));
+        result = new TargetFor(
+                forStmt.initializer.stream().map(converter::convert).toList(),
+                forStmt.condition != null ? converter.convert(forStmt.condition) : null,
+                forStmt.loopExpr.stream().map(converter::convert).toList(),
+                converter.convert(forStmt.block)
+        );
     }
 
     @Override

src/main/java/de/dhbwstuttgart/typeinference/typeAlgo/TYPEStmt.java

@@ -129,6 +129,7 @@ public class TYPEStmt implements StatementVisitor {
     @Override
     public void visit(ForStmt forStmt) {
         forStmt.initializer.forEach(s -> s.accept(this));
+        if (forStmt.condition != null)
             forStmt.condition.accept(this);
         forStmt.loopExpr.forEach(e -> e.accept(this));
         forStmt.block.accept(this);

src/test/java/TestComplete.java

@@ -841,4 +841,11 @@ public class TestComplete {
         var clazz = classFiles.get("Op2");
         var instance = clazz.getDeclaredConstructor().newInstance();
     }
+
+    @Test
+    public void testBug122() throws Exception {
+        var classFiles = generateClassFiles(new ByteArrayClassLoader(), "Bug122.jav");
+        var clazz = classFiles.get("Bug122");
+        var instance = clazz.getDeclaredConstructor().newInstance();
+    }
 }