From a14bbfbee9859fdd84adf0088c601121bb2a1a0c Mon Sep 17 00:00:00 2001
From: Boris Tyshkevich <btyshkevich@altinity.com>
Date: Thu, 24 Sep 2026 10:53:36 +0200
Subject: [PATCH] parser: distinguish scalar format calls from output clauses

---
 parser/altinity_format_test.go | 27 +++++++++++++++++++++++++++
 parser/parser_column.go        |  5 +++++
 2 files changed, 32 insertions(+)
 create mode 100644 parser/altinity_format_test.go

diff --git a/parser/altinity_format_test.go b/parser/altinity_format_test.go
new file mode 100644
index 0000000..f9c1886
--- /dev/null
+++ b/parser/altinity_format_test.go
@@ -0,0 +1,27 @@
+package parser
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSelectFormatFunctionAndOutputClause(t *testing.T) {
+	for _, sql := range []string{
+		"SELECT format('{}', 1)",
+		"SELECT 1, format('{}', 1)",
+		"SELECT 1, format('{}', 1) FORMAT JSON",
+		"SELECT 1 FORMAT JSON",
+	} {
+		t.Run(sql, func(t *testing.T) {
+			stmts, err := NewParser(sql).ParseStmts()
+			require.NoError(t, err)
+			require.Len(t, stmts, 1)
+			formatted := Format(stmts[0])
+			again, err := NewParser(formatted).ParseStmts()
+			require.NoError(t, err)
+			require.Len(t, again, 1)
+			require.Equal(t, formatted, Format(again[0]))
+		})
+	}
+}
diff --git a/parser/parser_column.go b/parser/parser_column.go
index b630193..c850694 100644
--- a/parser/parser_column.go
+++ b/parser/parser_column.go
@@ -517,6 +517,11 @@ func (p *Parser) keywordIsSelectItemIdentifier() bool {
 // that begins a clause following the SELECT item list. When true, we should
 // not treat the keyword itself as a bare alias.
 func (p *Parser) isSelectItemTerminatorKeyword() bool {
+	// FORMAT followed by '(' is a scalar function in the next SELECT item,
+	// not the output FORMAT clause. The latter takes a format name.
+	if p.matchKeyword(KeywordFormat) && p.peekTokenKind(TokenKindLParen) {
+		return false
+	}
 	if p.keywordIsSelectItemIdentifier() {
 		return false
 	}