Make sure that a variable that references an enum has to be initialized.

src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java

@@ -216,6 +216,11 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
       variableDeclaration = new VariableDeclaration(variableName, (Expression) expression);
       variableDeclaration.initialized = true;
     } else {
+      if (enumDefs.containsKey(declaredType.getName())) {
+        var error = "Variable " + variableName + " references an enum but is not initialized.";
+        throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+      }
+
       variableDeclaration = new VariableDeclaration(variableName);
     }
 

src/test/java/VariableDeclarationTest.java

@@ -21,7 +21,7 @@ public class VariableDeclarationTest {
     @Test
     void shouldNotThrowIfDeclaredTypeIsAnEnum() {
         // given
-        var tree = Helper.prepareParser("enum bar { A, B } function foo(): int { let a: bar; return 1; } foo();");
+        var tree = Helper.prepareParser("enum bar { A, B } function foo(): int { let a: bar = bar.A; return 1; } foo();");
         var ctxAnal = new ContextAnalysis(
                 Helper.getFuncs(tree),
                 Helper.getStructs(tree),
@@ -91,4 +91,19 @@ public class VariableDeclarationTest {
         var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
         assertEquals("Error in line 1:34 Redeclaration of variable with name \"x\".", e.getMessage());
     }
+
+    @Test
+    void shouldThrowExceptionIfVariableReferencesEnumButIsNotInitialized() {
+        // given
+        var tree = Helper.prepareParser("enum bar { A, B } function foo(): int { let x: bar; return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:40 Variable x references an enum but is not initialized.", e.getMessage());
+    }
 }