Add IS [NOT] DISTINCT FROM SOME/ANY/ALL (subquery) support

- Add SubqueryComparisonPredicate AST type for subquery comparisons
- Parse SOME/ANY/ALL with subqueries after IS [NOT] DISTINCT FROM
- Add marshaling for SubqueryComparisonPredicate
- Enable 2 passing tests

Author: claude

ast/subquery_comparison_predicate.go

@@ -0,0 +1,13 @@
+package ast
+
+// SubqueryComparisonPredicate represents a comparison with a subquery using ANY/SOME/ALL.
+// Example: col IS DISTINCT FROM SOME (SELECT ...), col > ALL (SELECT ...)
+type SubqueryComparisonPredicate struct {
+	Expression                      ScalarExpression
+	ComparisonType                  string // "IsDistinctFrom", "IsNotDistinctFrom", "Equals", etc.
+	Subquery                        *ScalarSubquery
+	SubqueryComparisonPredicateType string // "Any", "All"
+}
+
+func (s *SubqueryComparisonPredicate) node()              {}
+func (s *SubqueryComparisonPredicate) booleanExpression() {}

parser/marshal.go

@@ -2519,6 +2519,19 @@ func booleanExpressionToJSON(expr ast.BooleanExpression) jsonNode {
 		}
 		node["IsNot"] = e.IsNot
 		return node
+	case *ast.SubqueryComparisonPredicate:
+		node := jsonNode{
+			"$type":                          "SubqueryComparisonPredicate",
+			"ComparisonType":                 e.ComparisonType,
+			"SubqueryComparisonPredicateType": e.SubqueryComparisonPredicateType,
+		}
+		if e.Expression != nil {
+			node["Expression"] = scalarExpressionToJSON(e.Expression)
+		}
+		if e.Subquery != nil {
+			node["Subquery"] = scalarExpressionToJSON(e.Subquery)
+		}
+		return node
 	case *ast.BooleanInExpression:
 		node := jsonNode{
 			"$type": "InPredicate",

parser/parse_select.go

@@ -4330,6 +4330,43 @@ func (p *Parser) parseBooleanPrimaryExpression() (ast.BooleanExpression, error)
 				}, nil
 			}
 
+			// Check for SOME/ANY/ALL (subquery)
+			upperLit := strings.ToUpper(p.curTok.Literal)
+			if upperLit == "SOME" || upperLit == "ANY" || upperLit == "ALL" {
+				predicateType := "Any"
+				if upperLit == "ALL" {
+					predicateType = "All"
+				}
+				p.nextToken() // consume SOME/ANY/ALL
+
+				if p.curTok.Type != TokenLParen {
+					return nil, fmt.Errorf("expected ( after %s, got %s", upperLit, p.curTok.Literal)
+				}
+				p.nextToken() // consume (
+
+				subqueryExpr, err := p.parseQueryExpression()
+				if err != nil {
+					return nil, err
+				}
+
+				if p.curTok.Type != TokenRParen {
+					return nil, fmt.Errorf("expected ), got %s", p.curTok.Literal)
+				}
+				p.nextToken() // consume )
+
+				compType := "IsDistinctFrom"
+				if isNot {
+					compType = "IsNotDistinctFrom"
+				}
+
+				return &ast.SubqueryComparisonPredicate{
+					Expression:                      left,
+					ComparisonType:                  compType,
+					Subquery:                        &ast.ScalarSubquery{QueryExpression: subqueryExpr},
+					SubqueryComparisonPredicateType: predicateType,
+				}, nil
+			}
+
 			// Parse the second expression
 			secondExpr, err := p.parseScalarExpression()
 			if err != nil {

parser/testdata/Baselines160_SelectStatementTests160/metadata.json

@@ -1 +1 @@
-{"todo": true}
+{}

parser/testdata/SelectStatementTests160/metadata.json

@@ -1 +1 @@
-{"todo": true}
+{}