go-gorm/sharding plugin would fail when combining with hints.ForceIndex in MySQL

[zhaojames0707]

GORM Playground Link

go-gorm/playground#726

Description

I create a logical table named message, and use two underlying sharding tables: message_01 and message_02.
When using go-gorm/sharding plugin alone, everything works well, as in test case TestSharding.
However, after I added Clauses(hints.ForceIndex("idx_content")) in the query, the sharding plugin would fail, as in test case TestShardingAndForceIndex.
The error log shows Error 1146 (42S02): Table 'gorm.message' doesn't exist.
After some digging up, I found the cause of the issue comes from this line:

sharding/sharding.go

Line 307 in 1ccc174

expr, err := sqlparser.NewParser(strings.NewReader(query)).ParseStatement()

It seems sqlparser can't handle the FORCE INDEX syntax in SQL, causing the sharding plugin fails and falls back to original(not sharded) SQL.
A relevant issue: #91

[zhaojames0707]

@jinzhu

[fomalhaut-w]

any update？