Ban enums as variadic arguments (#628)

compiler/typecheck/step3_function_and_method_bodies.jou

@@ -623,6 +623,13 @@ def typecheck_function_or_method_call(ft: FileTypes*, call: AstCall*, self_type:
             do_implicit_cast(ft->current_fom_types, &call->args[i], intType, Location{}, NULL)
         elif t == floatType:
             do_implicit_cast(ft->current_fom_types, &call->args[i], doubleType, Location{}, NULL)
+        elif t->kind == TypeKind.Enum:
+            snprintf(
+                msg, sizeof(msg),
+                "enums cannot be passed to functions that take variadic arguments, such as %s",
+                sig->name,
+            )
+            fail(call->args[i].location, msg)
 
     free(sigstr)
     return sig->returntype
@@ -1017,7 +1024,7 @@ def typecheck_expression(ft: FileTypes*, expr: AstExpression*) -> None:
             do_explicit_cast(ft->current_fom_types, &expr->as_->value, result, expr->location)
 
         case _:
-            printf("%d\n", expr->kind)
+            printf("%d\n", expr->kind as int)
             assert False
 
     assert result != NULL

tests/wrong_type/enum_as_vararg.jou

@@ -0,0 +1,9 @@
+import "stdlib/io.jou"
+
+enum Foo:
+    Bar
+    Baz
+
+def main() -> int:
+    printf("%d\n", Foo.Bar)  # Error: enums cannot be passed to functions that take variadic arguments, such as printf
+    return 0