From a8a8324fc365e51b7e93fb09571e90b6abb3a7d8 Mon Sep 17 00:00:00 2001
From: H.G. Muller <h.g.muller@hccnet.nl>
Date: Tue, 11 Jan 2011 16:12:02 +0100
Subject: [PATCH] Fix legality testing for promotions

Turns out WB has never tested for the legality of the chosen promotion
piece, and would allow promotion to King innorml chess even with
legality testing on (when entered through the keyboard)! Now strict
testing is done, outlawing Pawns and Kings (or Unicorns in
Knightmate). Only in suicide / giveaway Kings are stillallowed, and in
spartan a black King if you do not have two yet.(And promotion
toLnce,representing Hoplite Pawn,is forbidden there.)
---
 moves.c |   19 ++++++++++++++++---
 1 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/moves.c b/moves.c
index 17c1239..cb3584a 100644
--- a/moves.c
+++ b/moves.c
@@ -1170,10 +1170,23 @@ if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promo
     if (promoChar != NULLCHAR) {
 	if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
 	if (cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
-	    if(CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(promoChar) : ToLower(promoChar)) == EmptySquare)
+	    ChessSquare piece = CharToPiece(flags & F_WHITE_ON_MOVE ? ToUpper(promoChar) : ToLower(promoChar));
+	    if(piece == EmptySquare)
                 cl.kind = ImpossibleMove; // non-existing piece
-	    if(gameInfo.variant == VariantSpartan && cl.kind == BlackPromotion && promoChar != PieceToChar(BlackKing) &&
-	       CheckTest(board, flags, rf, ff, rt, ft, FALSE)) cl.kind = IllegalMove; // [HGM] spartan: only promotion to King was possible
+	    if(gameInfo.variant == VariantSpartan && cl.kind == BlackPromotion ) {
+		if(promoChar != PieceToChar(BlackKing)) {
+		    if(CheckTest(board, flags, rf, ff, rt, ft, FALSE)) cl.kind = IllegalMove; // [HGM] spartan: only promotion to King was possible
+		    if(piece == BlackLance) cl.kind = ImpossibleMove;
+		} else { // promotion to King allowed only if we do not haave two yet
+		    int r, f, kings = 0;
+		    for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) kings += (board[r][f] == BlackKing);
+		    if(kings == 2) cl.kind = IllegalMove;
+		}
+	    } else if(piece == WhitePawn || piece == BlackPawn) cl.kind = ImpossibleMove; // cannot stay Pawn in any variant
+	    else if((piece == WhiteUnicorn || piece == BlackUnicorn) && gameInfo.variant == VariantKnightmate)
+             cl.kind = IllegalMove; // promotion to Royal Knight not allowed
+	    else if((piece == WhiteKing || piece == BlackKing) && gameInfo.variant != VariantSuicide && gameInfo.variant != VariantGiveaway)
+             cl.kind = IllegalMove; // promotion to King usually not allowed
 	} else {
 	    cl.kind = IllegalMove;
 	}
-- 
1.7.0.4