Here's a position in a chess puzzle:
[Title "White to move"]
[fen "5rk1/p7/Q1n3pp/3q1p1n/2B2P2/4P2P/P5rK/R4R2 w - - 0 1"]
The rook had captured a pawn, resulting in a check. The rook is supported by the Queen, but the Queen itself is pinned by the bishop and hence will not be able to protect the rook if the King takes it.
Shouldn't King-captures-Rook be a valid move in this case?