From 95390b99801a3539e0b0f8510d4e68058f2c47df Mon Sep 17 00:00:00 2001
From: Davin McCall <davmac@davmac.org>
Date: Sun, 24 Dec 2017 11:36:26 +0000
Subject: [PATCH] Update Dasynq to 1.0.3.

---
 src/dasynq/dasynq-daryheap.h | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/dasynq/dasynq-daryheap.h b/src/dasynq/dasynq-daryheap.h
index 36209fc..9bb61ca 100644
--- a/src/dasynq/dasynq-daryheap.h
+++ b/src/dasynq/dasynq-daryheap.h
@@ -46,7 +46,6 @@ class dary_heap
 
     using hindex_t = typename decltype(hvec)::size_type;
 
-    int root_node = -1;
     hindex_t num_nodes = 0;
 
     public:
@@ -56,7 +55,15 @@ class dary_heap
     // separate container, and have the handle be an index into that container).
     struct handle_t
     {
-        T hd;
+        union hd_u_t {
+            // The data member is kept in a union so it doesn't get constructed/destructed
+            // automatically, and we can construct it lazily.
+            public:
+            hd_u_t() { }
+            ~hd_u_t() { }
+            T hd;
+        } hd_u;
+
         hindex_t heap_index;
 
         handle_t(const handle_t &) = delete;
@@ -111,8 +118,12 @@ class dary_heap
 
     void bubble_up(hindex_t pos, handle_t &h, const P &p) noexcept
     {
-        Compare lt;
         hindex_t rmax = hvec.size() - 1;
+        if (rmax == 0) {
+            return;
+        }
+
+        Compare lt;
         hindex_t max = (rmax - 1) / N;
 
         while (pos <= max) {
@@ -155,14 +166,14 @@ class dary_heap
 
     T & node_data(handle_t & index) noexcept
     {
-        return index.hd;
+        return index.hd_u.hd;
     }
 
     // Allocate a slot, but do not incorporate into the heap:
     //  u... : parameters for data constructor T::T(...)
     template <typename ...U> void allocate(handle_t & hnd, U... u)
     {
-        new (& hnd.hd) T(u...);
+        new (& hnd.hd_u.hd) T(u...);
         hnd.heap_index = -1;
         constexpr hindex_t max_allowed = std::numeric_limits<hindex_t>::is_signed ?
                 std::numeric_limits<hindex_t>::max() : ((hindex_t) - 2);
@@ -193,6 +204,7 @@ class dary_heap
     void deallocate(handle_t & index) noexcept
     {
         num_nodes--;
+        index.hd_u.hd.~T();
 
         // shrink the capacity of hvec if num_nodes is sufficiently less than
         // its current capacity:
-- 
2.25.1