Fix a bogus assert in allows()

Becuase castle is coded as "king captures the rook"
the to_sq(move), A1/8 or H1/8 is empty after the move,
leading to assert assert(p != NO_PIECE) in color_of().

Teach allows() asserts about castle and fix the crash.

Bug reported by Ryan Takker and tracked down by Tom Vijlbrief.

No functional change.

diff --git a/src/search.cpp b/src/search.cpp
index c85cdb5d689fcc1ee47f336812a1d9d310595ec0..7b43f64a19e63510ba69ed8dfd50e610cf3be5c0 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1400,7 +1400,7 @@ moves_loop: // When in check and at SpNode search starts from here
     assert(is_ok(first));
     assert(is_ok(second));
     assert(color_of(pos.piece_on(from_sq(second))) == ~pos.side_to_move());
-    assert(color_of(pos.piece_on(to_sq(first))) == ~pos.side_to_move());
+    assert(type_of(first) == CASTLE || color_of(pos.piece_on(to_sq(first))) == ~pos.side_to_move());
 
     Square m1from = from_sq(first);
     Square m2from = from_sq(second);