[mono] Don't save byref `System.Void` into `MonoDomain::typeof_void`. (#40405)

`mono_type_get_object_checked` will return the `MonoReflectionType`
referred to by `MonoDomain::typeof_void` if present. If a byref
`System.Void` is stored in this field, then
`get_ContainsGenericParameters` applied to `System.Void` will loop
indefinitely, because our implementation of
`get_ContainsGenericParameters` expects `GetElementType` to yield a
`MonoReflectionType` with one layer of "type function application"
removed.

Fixes https://github.com/dotnet/runtime/issues/37489.

diff --git a/src/mono/mono/metadata/reflection.c b/src/mono/mono/metadata/reflection.c
index c28ce82..09851b3 100644 (file)
--- a/src/mono/mono/metadata/reflection.c
+++ b/src/mono/mono/metadata/reflection.c
@@ -570,7 +570,7 @@ mono_type_get_object_checked (MonoDomain *domain, MonoType *type, MonoError *err
        res->type = type;
        mono_g_hash_table_insert_internal (domain->type_hash, type, res);
 
-       if (type->type == MONO_TYPE_VOID)
+       if (type->type == MONO_TYPE_VOID && !type->byref)
                domain->typeof_void = (MonoObject*)res;
 
        mono_domain_unlock (domain);