X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=45be5df3203b26a0c4fe5ffccb25468033692ba0;hp=f558d73c67992138f1d96ec12521f8ed26027539;hb=8de91be61e0910936e3d6be6e1033a4fb8537dca;hpb=8c9c51c721f01eaf000924f493ced2ab6bec9e91

diff --git a/src/position.cpp b/src/position.cpp
index f558d73c..45be5df3 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -479,7 +479,6 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
       return true;
 
   Color us = side_to_move();
-  Color them = opposite_color(us);
   Square from = move_from(m);
   Square ksq = king_square(us);
 
@@ -491,6 +490,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   // after the move is made
   if (move_is_ep(m))
   {
+      Color them = opposite_color(us);
       Square to = move_to(m);
       Square capsq = make_square(square_file(to), square_rank(from));
       Bitboard b = occupied_squares();
@@ -511,11 +511,12 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const {
   // If the moving piece is a king, check whether the destination
   // square is attacked by the opponent.
   if (from == ksq)
-      return !(square_is_attacked(move_to(m), them));
+      return !(square_is_attacked(move_to(m), opposite_color(us)));
 
   // A non-king move is legal if and only if it is not pinned or it
   // is moving along the ray towards or away from the king.
-  return (   !bit_is_set(pinned, from)
+  return (   !pinned
+          || !bit_is_set(pinned, from)
           || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq)));
 }
 
@@ -551,7 +552,8 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) const {
       if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check?
           return true;
 
-      if (    bit_is_set(dcCandidates, from)      // Discovered check?
+      if (   dcCandidates // Discovered check?
+          && bit_is_set(dcCandidates, from)
           && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq)))
           return true;
 
@@ -590,22 +592,26 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) const {
       }
       return false;
 
+  // Test discovered check and normal check according to piece type
   case KNIGHT:
-    return   bit_is_set(dcCandidates, from)              // Discovered check?
-          || bit_is_set(piece_attacks<KNIGHT>(ksq), to); // Normal check?
+    return   (dcCandidates && bit_is_set(dcCandidates, from))
+          || bit_is_set(piece_attacks<KNIGHT>(ksq), to);
 
   case BISHOP:
-    return   bit_is_set(dcCandidates, from)              // Discovered check?
-          || bit_is_set(piece_attacks<BISHOP>(ksq), to); // Normal check?
+    return   (dcCandidates && bit_is_set(dcCandidates, from))
+          || (   direction_between_squares(ksq, to) != DIR_NONE
+              && bit_is_set(piece_attacks<BISHOP>(ksq), to));
 
   case ROOK:
-    return   bit_is_set(dcCandidates, from)              // Discovered check?
-          || bit_is_set(piece_attacks<ROOK>(ksq), to);   // Normal check?
+    return   (dcCandidates && bit_is_set(dcCandidates, from))
+          || (   direction_between_squares(ksq, to) != DIR_NONE
+              && bit_is_set(piece_attacks<ROOK>(ksq), to));
 
   case QUEEN:
       // Discovered checks are impossible!
       assert(!bit_is_set(dcCandidates, from));
-      return bit_is_set(piece_attacks<QUEEN>(ksq), to);  // Normal check?
+      return (   direction_between_squares(ksq, to) != DIR_NONE
+              && bit_is_set(piece_attacks<QUEEN>(ksq), to));
 
   case KING:
       // Discovered check?