From: Marco Costalba <mcostalba@gmail.com>
Date: Sun, 13 Aug 2017 18:01:26 +0000 (-0700)
Subject: Fix involuntary conversions of ExtMove to Move
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=d482e3a8905ee194bda3f67a21dda5132c21f30b;hp=9001f55147fa304223623a6de0025ffe79f5fcc3

Fix involuntary conversions of ExtMove to Move

The trick is to create an ambiguity for the
compiler in case an unwanted conversion to
Move is attempted like in:

    ExtMove m1{Move(17),4}, m2{Move(4),17};

    std::cout << (m1 < m2) << std::endl; // 1
    std::cout << (m1 > m2) << std::endl; // 1(!)

This fixes issue #1204

No functional change.
---

diff --git a/src/movegen.h b/src/movegen.h
index 8ae80118..82560570 100644
--- a/src/movegen.h
+++ b/src/movegen.h
@@ -42,6 +42,10 @@ struct ExtMove {
 
   operator Move() const { return move; }
   void operator=(Move m) { move = m; }
+
+  // Inhibit unwanted implicit conversions to Move
+  // with an ambiguity that yields to a compile error.
+  operator float() const;
 };
 
 inline bool operator<(const ExtMove& f, const ExtMove& s) {