From 5a8ac1559c9fc597e6dcb29f64a55da8763ba9c9 Mon Sep 17 00:00:00 2001
From: Michael Lill <michael.lill@tokiwa.software>
Date: Fri, 3 Nov 2023 12:17:44 +0100
Subject: [PATCH] add pre-condition, not adding fixed features to inherited
 features

---
 src/dev/flang/fe/Module.java | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/dev/flang/fe/Module.java b/src/dev/flang/fe/Module.java
index cd0c7f09f..05e7679f8 100644
--- a/src/dev/flang/fe/Module.java
+++ b/src/dev/flang/fe/Module.java
@@ -28,7 +28,6 @@
 
 import dev.flang.ast.AbstractFeature;
 import dev.flang.ast.AstErrors;
-import dev.flang.ast.Consts;
 import dev.flang.ast.FeatureName;
 import dev.flang.ast.State;
 import dev.flang.ast.Types;
@@ -214,7 +213,7 @@ void findInheritedFeatures(SortedMap<FeatureName, AbstractFeature> set, Abstract
                 if (CHECKS) check
                   (cf != outer);
 
-                if ((f.modifiers() & Consts.MODIFIER_FIXED) == 0)
+                if (!f.isFixed())
                   {
                     var newfn = cf.handDown(null, f, fn, p, outer);
                     addInheritedFeature(set, outer, p, newfn, f);
@@ -254,6 +253,9 @@ void addInheritedFeature(SortedMap<FeatureName, AbstractFeature> set,
                            FeatureName fn,
                            AbstractFeature f)
   {
+    if (PRECONDITIONS)
+      require(!f.isFixed());
+
     var existing = set.get(fn);
     if (existing != null)
       {