Massive multiple-input-multiple-output (MIMO) systems have been proposed to support high rate multiple access. As channel estimation in massive MIMO suffers from the wellknown impairment of pilot contamination, we propose a novel approach to multi-user detection by exploiting forward error correction (FEC) code diversity. Unlike traditional approaches solely based on worst-case or probabilistic channel estimation errors, we develop a joint quadratic-programming (QP) receiver anchored with a set of FEC code constraints. Exploiting the user signatures presented by FEC channel codes of distinct permutations, our receiver can effectively recover signals from pilot-interfering users. The code-anchored robust design (CARD) method can also be applied to a chance-constrained receiver, which shows further performance gain compared with the direct integration of FEC code constraints in joint QP receiver. The effectiveness of CARD receivers is demonstrated by numerical results that establish substantial performance gain of the proposed receivers over existing robust designs. In addition, we present a distributed multi-cell processing scheme for enhanced performance via alternating direction method of multipliers (ADMM).