Do not allow inheriting built-in classes Num, Bool and Null (#831)

* Do not allow inheriting `Num`, `Bool` and `Null`. fixes #830
wren-lang · Oct 26, 2020 · 44d6d20 · 44d6d20
1 parent ad4e039
commit 44d6d20
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Showing 4 changed files with 7 additions and 1 deletion.
diff --git a/src/vm/wren_vm.c b/src/vm/wren_vm.c
@@ -512,7 +512,10 @@ static Value validateSuperclass(WrenVM* vm, Value name, Value superclassValue,
       superclass == vm->listClass ||
       superclass == vm->mapClass ||
       superclass == vm->rangeClass ||
-      superclass == vm->stringClass)
+      superclass == vm->stringClass ||
+      superclass == vm->boolClass ||
+      superclass == vm->nullClass ||
+      superclass == vm->numClass)
   {
     return wrenStringFormat(vm,
         "Class '@' cannot inherit from built-in class '@'.",

diff --git a/test/language/inheritance/inherit_from_bool.wren b/test/language/inheritance/inherit_from_bool.wren
@@ -0,0 +1 @@
+class Subclass is Bool {} // expect runtime error: Class 'Subclass' cannot inherit from built-in class 'Bool'.
diff --git a/test/language/inheritance/inherit_from_null_class.wren b/test/language/inheritance/inherit_from_null_class.wren
@@ -0,0 +1 @@
+class Subclass is Null {} // expect runtime error: Class 'Subclass' cannot inherit from built-in class 'Null'.
diff --git a/test/language/inheritance/inherit_from_num.wren b/test/language/inheritance/inherit_from_num.wren
@@ -0,0 +1 @@
+class Subclass is Num {} // expect runtime error: Class 'Subclass' cannot inherit from built-in class 'Num'.