Support row alias on INSERT ... VALUES/SET (#22) (#34)

* Support row alias on INSERT ... VALUES/SET (#22)

MySQL 8.0.19 added a row alias on the inserted row
(`INSERT ... VALUES (...) AS new ON DUPLICATE KEY UPDATE col = new.col`)
to replace the deprecated `VALUES(col)` function inside the update list.

Extend `InsertStmt` with `RowAlias` and `ColumnAliases`, and add the
optional `AS row_alias [(col_alias_list)]` slot to the `VALUES` and `SET`
forms of `InsertValues`. The `SELECT` form is intentionally left out:
attaching the alias there propagates `AS` into the column-alias FOLLOW
set inside `SELECT` and yields a shift/reduce conflict that goyacc
rejects.

REPLACE is left unchanged; it has no ON DUPLICATE KEY UPDATE, so a row
alias is meaningless there.

* Ignore parser/genkeyword build artifact

The Makefile's genkeyword target produces a Go binary at parser/genkeyword
that's used by `go generate`. It's a build output, not source.

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: kyleconroy

.gitignore

@@ -4,3 +4,4 @@ y.go
 .idea/
 .vscode/
 coverage.txt
+parser/genkeyword

ast/dml.go

@@ -2399,6 +2399,12 @@ type InsertStmt struct {
 	Priority    mysql.PriorityEnum
 	OnDuplicate []*Assignment
 	Select      ResultSetNode
+	// RowAlias is the alias for the inserted row, set by `INSERT ... AS row_alias`.
+	// MySQL 8.0.19+ syntax for use inside ON DUPLICATE KEY UPDATE.
+	RowAlias *CIStr
+	// ColumnAliases are the optional column aliases that follow RowAlias,
+	// set by `INSERT ... AS row_alias (col_alias_list)`.
+	ColumnAliases []*CIStr
 	// TableHints represents the table level Optimizer Hint for join type.
 	TableHints     []*TableOptimizerHint
 	PartitionNames []CIStr
@@ -2516,6 +2522,20 @@ func (n *InsertStmt) Restore(ctx *format.RestoreCtx) error {
 			return fmt.Errorf("Incorrect type for InsertStmt.Select: %T", v)
 		}
 	}
+	if n.RowAlias != nil {
+		ctx.WriteKeyWord(" AS ")
+		ctx.WriteName(n.RowAlias.O)
+		if len(n.ColumnAliases) != 0 {
+			ctx.WritePlain("(")
+			for i, c := range n.ColumnAliases {
+				if i != 0 {
+					ctx.WritePlain(",")
+				}
+				ctx.WriteName(c.O)
+			}
+			ctx.WritePlain(")")
+		}
+	}
 	if n.OnDuplicate != nil {
 		ctx.WriteKeyWord(" ON DUPLICATE KEY UPDATE ")
 		for i, v := range n.OnDuplicate {