[map] Allow invalid items to be pointer to static object

By derefencing them when necessary.

Also, we do not rely on trivially-copyable, so remove that assertion.

src/hb-algs.hh

@@ -211,8 +211,11 @@ struct
 }
 HB_FUNCOBJ (hb_bool);
 
-template <typename T> T hb_coerce (const T v) { return v; }
-template <typename T> T hb_coerce (const T *v) { return *v; }
+template <typename T>
+T hb_coerce (const T v) { return v; }
+template <typename T, typename V,
+	  hb_enable_if (!hb_is_same (hb_decay<T>, hb_decay<V>) && hb_is_pointer(V))>
+T hb_coerce (const V v) { return *v; }
 
 struct
 {

src/hb-map.hh

@@ -61,8 +61,6 @@ struct hb_hashmap_t
     hb_copy (o, *this);
   }
 
-  static_assert (std::is_trivially_copyable<K>::value, "");
-  static_assert (std::is_trivially_copyable<V>::value, "");
   static_assert (std::is_trivially_destructible<K>::value, "");
   static_assert (std::is_trivially_destructible<V>::value, "");
 
@@ -75,9 +73,9 @@ struct hb_hashmap_t
     void clear ()
     {
       new (hb_addressof (key)) K ();
-      key = kINVALID;
+      key = hb_coerce<K> (kINVALID);
       new (hb_addressof (value)) V ();
-      value = vINVALID;
+      value = hb_coerce<V> (vINVALID);
       hash = 0;
     }
 
@@ -85,19 +83,19 @@ struct hb_hashmap_t
     bool operator == (const item_t &o) { return *this == o.key; }
     bool is_unused () const
     {
-      const K inv = kINVALID;
+      const K inv = hb_coerce<K> (kINVALID);
       return key == inv;
     }
     bool is_tombstone () const
     {
-      const K kinv = kINVALID;
-      const V vinv = vINVALID;
+      const K kinv = hb_coerce<K> (kINVALID);
+      const V vinv = hb_coerce<V> (vINVALID);
       return key != kinv && value == vinv;
     }
     bool is_real () const
     {
-      const K kinv = kINVALID;
-      const V vinv = vINVALID;
+      const K kinv = hb_coerce<K> (kINVALID);
+      const V vinv = hb_coerce<V> (vINVALID);
       return key != kinv && value != vinv;
     }
     hb_pair_t<K, V> get_pair() const { return hb_pair_t<K, V> (key, value); }
@@ -196,12 +194,12 @@ struct hb_hashmap_t
 
   V get (K key) const
   {
-    if (unlikely (!items)) return vINVALID;
+    if (unlikely (!items)) return hb_coerce<V> (vINVALID);
     unsigned int i = bucket_for (key);
-    return items[i].is_real () && items[i] == key ? items[i].value : vINVALID;
+    return items[i].is_real () && items[i] == key ? items[i].value : hb_coerce<V> (vINVALID);
   }
 
-  void del (K key) { set (key, vINVALID); }
+  void del (K key) { set (key, hb_coerce<V> (vINVALID)); }
 
   /* Has interface. */
   typedef V value_t;
@@ -210,7 +208,7 @@ struct hb_hashmap_t
   {
     V v = (*this)[k];
     if (vp) *vp = v;
-    const V vinv = vINVALID;
+    const V vinv = hb_coerce<V> (vINVALID);
     return v != vinv;
   }
   /* Projection. */
@@ -266,12 +264,12 @@ struct hb_hashmap_t
   bool set_with_hash (K key, uint32_t hash, VV&& value)
   {
     if (unlikely (!successful)) return false;
-    const K kinv = kINVALID;
+    const K kinv = hb_coerce<K> (kINVALID);
     if (unlikely (key == kinv)) return true;
     if (unlikely ((occupancy + occupancy / 2) >= mask && !resize ())) return false;
     unsigned int i = bucket_for_hash (key, hash);
 
-    const V vinv = vINVALID;
+    const V vinv = hb_coerce<V> (vINVALID);
     if (value == vinv && items[i].key != key)
       return true; /* Trying to delete non-existent key. */