[parser] parser,ast: fix the TiDB issue #8153 (#20)

pingcap · Oct 9, 2021 · 4924685 · 4924685
1 parent ad9281a
commit 4924685
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Showing 3 changed files with 17 additions and 14 deletions.
diff --git a/parser/ast/expressions.go b/parser/ast/expressions.go
@@ -699,7 +699,7 @@ func (n *ParenthesesExpr) Accept(v Visitor) (Node, bool) {
 type PositionExpr struct {
 	exprNode
 	// N is the position, started from 1 now.
-	N int
+	N ExprNode
 	// Refer is the result field the position refers to.
 	Refer *ResultField
 }
@@ -716,6 +716,13 @@ func (n *PositionExpr) Accept(v Visitor) (Node, bool) {
 		return v.Leave(newNode)
 	}
 	n = newNode.(*PositionExpr)
+	if n.N != nil {
+		node, ok := n.N.Accept(v)
+		if !ok {
+			return n, false
+		}
+		n.N = node.(ExprNode)
+	}
 	return v.Leave(n)
 }
 

diff --git a/parser/parser.go b/parser/parser.go
diff --git a/parser/parser.y b/parser/parser.y
@@ -3187,13 +3187,11 @@ ByItem:
 	Expression Order
 	{
 		expr := $1
-		valueExpr, ok := expr.(ast.ValueExpr)
-		if ok {
-			position, isPosition := valueExpr.GetValue().(int64)
-			if isPosition {
-				expr = &ast.PositionExpr{N: int(position)}
-			}
-		}
+		if valueExpr, ok := expr.(ast.ValueExpr); ok {
+			expr = &ast.PositionExpr{N: valueExpr}
+		} else if paramExpr, ok := expr.(ast.ParamMarkerExpr); ok {
+			expr = &ast.PositionExpr{N: paramExpr}
+ 		}
 		$$ = &ast.ByItem{Expr: expr, Desc: $2.(bool)}
 	}