From bbdab9889a6ed0999055f94c1db7ddf5de993b95 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <steinar+chess@gunderson.no>
Date: Thu, 25 Dec 2025 23:01:08 +0100
Subject: [PATCH] Unbreak MPI compilation.

3c2c7b01bd deleted the TTCache default constructor, but we need it
when MPI is active. This wasn't discovered during the merging,
and it is hard to put it properly into the commit history due to
rebase/rerere shortcomings. (This means that some of the merge
commits will not compile with MPI on, and this patch needs to be
added on top if bisecting.)
---
 src/tt.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/tt.h b/src/tt.h
index a92de2856..6676193f9 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -56,7 +56,12 @@ struct TTData {
     Bound bound;
     bool  is_pv;
 
+#ifdef USE_MPI
+    // We need this for TTCache to be constructible.
+    TTData() = default;
+#else
     TTData() = delete;
+#endif
 
     // clang-format off
     TTData(Move m, Value v, Value ev, Depth d, Bound b, bool pv) :