kernel: Ensure `dict` always hashes to the same value given the same contents.

diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index 18114b6ad119ff6e27b29a909f62f8d7b2e0b163..1284f3f8d2ac861233137f6f5db950802a72ac80 100644 (file)
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -207,6 +207,7 @@ class dict
                entry_t() { }
                entry_t(const std::pair<K, T> &udata, int next) : udata(udata), next(next) { }
                entry_t(std::pair<K, T> &&udata, int next) : udata(std::move(udata)), next(next) { }
+               bool operator<(const entry_t &other) const { return udata.first < other.udata.first; }
        };
 
        std::vector<int> hashtable;
@@ -616,10 +617,12 @@ public:
        }
 
        unsigned int hash() const {
+               std::vector<entry_t> entries_(entries); //make a copy to preserve const-ness
+               std::sort(entries_.begin(), entries_.end());
                unsigned int h = mkhash_init;
-               for (auto &it : entries) {
-                       h = mkhash(h, hash_ops<K>::hash(it.udata.first));
-                       h = mkhash(h, hash_ops<T>::hash(it.udata.second));
+               for (unsigned int i = 0; i < entries_.size(); ++i) {
+                       h = mkhash(h, hash_ops<K>::hash(entries_[i].udata.first));
+                       h = mkhash(h, hash_ops<T>::hash(entries_[i].udata.second));
                }
                return h;
        }