expression: extract process of getting full cmp type to method. (#4935)
expression: extract process of getting full cmp type to method. (#4935)


wusphinx/tidb,CodeRushing/tidb,c4pt0r/tidb,mccxj/tidb,pingcap/tidb,pingcap/tidb,c4pt0r/tidb,qiuyesuifeng/tidb,pingcap/tidb,spongedu/tidb,pingcap/tidb,c4pt0r/tidb,pingcap/tidb,cosmtrek/tidb,ngaut/tidb,c4pt0r/tidb,qiuyesuifeng/tidb,yangwenmai/tidb,EvilMcJerkface/tidb,kyle-wang/tidb,ngaut/tidb,spongedu/tidb,tiancaiamao/tidb,CodeRushing/tidb,XuHuaiyu/tidb,EvilMcJerkface/tidb,XuHuaiyu/tidb,coocood/tidb,ngaut/tidb,ming-relax/tidb,wusphinx/tidb,kyle-wang/tidb,ngaut/tidb,cosmtrek/tidb,kyle-wang/tidb,Nify/tidb,ming-relax/tidb,yangwenmai/tidb,kyle-wang/tidb,kyle-wang/tidb,kyle-wang/tidb,ngaut/tidb,Nify/tidb,c4pt0r/tidb,Cofyc/tidb,ngaut/tidb,pingcap/tidb,tiancaiamao/tidb,c4pt0r/tidb,mccxj/tidb,coocood/tidb,Cofyc/tidb