Snowflake: parse nested COPY transformation paths

src/dialect/snowflake.rs

@@ -1760,6 +1760,18 @@ fn parse_select_item_for_data_load(
         }
     }
 
+    // A simple staged field has a dedicated compact AST node. More complex
+    // paths and casts must fall back to the standard expression parser so it
+    // can preserve the complete `JsonAccess` / `Cast` expression instead of
+    // leaving trailing tokens for the enclosing COPY parser.
+    if matches!(
+        parser.peek_token_ref().token,
+        Token::Colon | Token::Period | Token::LBracket | Token::DoubleColon
+    ) {
+        let token = parser.next_token();
+        return parser.expected("end of simple staged field", token);
+    }
+
     // as
     if parser.parse_keyword(Keyword::AS) {
         item_as = Some(match parser.next_token().token {

tests/sqlparser_snowflake.rs

@@ -2668,6 +2668,29 @@ fn test_copy_into_with_transformations() {
     snowflake().parse_sql_statements(sql1).unwrap();
 }
 
+#[test]
+fn test_copy_into_with_nested_transformation_path() {
+    let sql = concat!(
+        "COPY INTO cities FROM ",
+        "(SELECT $1:continent::VARCHAR, $1:country:name::VARCHAR ",
+        "FROM @sf_tut_stage/cities.parquet)"
+    );
+
+    let statement = snowflake().verified_stmt(sql);
+    assert_eq!(statement.to_string(), sql);
+    let Statement::CopyIntoSnowflake {
+        from_transformations: Some(transformations),
+        ..
+    } = statement
+    else {
+        panic!("expected COPY transformations");
+    };
+    assert!(transformations.iter().all(|item| matches!(
+        item,
+        StageLoadSelectItemKind::SelectItem(SelectItem::UnnamedExpr(Expr::Cast { .. }))
+    )));
+}
+
 #[test]
 fn test_copy_into_file_format() {
     let sql = concat!(