tree: add FmtHideHints flag

Add FmtHideHints flag which skips over hints when formatting an
AST. This will be used by hint injection to validate that the donor
statement matches the target statement.

Informs: #153633

Release note: None

Author: michae2

pkg/sql/sem/tree/format.go

@@ -197,6 +197,9 @@ const (
 	// FmtSkipAsOfSystemTimeClauses prevents the formatter from printing AS OF
 	// SYSTEM TIME clauses.
 	FmtSkipAsOfSystemTimeClauses
+
+	// FmtHideHints skips over any hints.
+	FmtHideHints
 )
 
 const genericArityIndicator = "__more__"

pkg/sql/sem/tree/select.go

@@ -611,7 +611,7 @@ func (node *AliasedTableExpr) Format(ctx *FmtCtx) {
 		ctx.WriteString("LATERAL ")
 	}
 	ctx.FormatNode(node.Expr)
-	if node.IndexFlags != nil {
+	if node.IndexFlags != nil && !ctx.HasFlags(FmtHideHints) {
 		ctx.FormatNode(node.IndexFlags)
 	}
 	if node.Ordinality {
@@ -681,7 +681,7 @@ func (node *JoinTableExpr) Format(ctx *FmtCtx) {
 		if node.JoinType != "" {
 			ctx.WriteString(node.JoinType)
 			ctx.WriteByte(' ')
-			if node.Hint != "" {
+			if node.Hint != "" && !ctx.HasFlags(FmtHideHints) {
 				ctx.WriteString(node.Hint)
 				ctx.WriteByte(' ')
 			}
@@ -693,7 +693,7 @@ func (node *JoinTableExpr) Format(ctx *FmtCtx) {
 		if node.JoinType != "" {
 			ctx.WriteString(node.JoinType)
 			ctx.WriteByte(' ')
-			if node.Hint != "" {
+			if node.Hint != "" && !ctx.HasFlags(FmtHideHints) {
 				ctx.WriteString(node.Hint)
 				ctx.WriteByte(' ')
 			}