```
$ echo '20210101,A' | clickhouse-local --input-format CSV --structure 'd Date, s String' --query "SELECT * FROM table"
Code: 27. DB::Exception: Cannot parse input: expected ',' before: '20210101,A\n': 
Row 1:
Column 0,   name: d, type: Date,   ERROR: text "20210101,A" is not like Date

: While executing ParallelParsingBlockInputFormat: While executing File. (CANNOT_PARSE_INPUT_ASSERTION_FAILED)
```

**How to solve**

Disambiguate while parsing by absense of separators between YYYY-MM-DD.
char hex_code[4];
            if (4 != buf.read(hex_code, 4))
                return error("Cannot parse escape sequence: less than four bytes after \\u", ErrorCodes::CANNOT_PARSE_ESCAPE_SEQUENCE);
            
            if (0 == memcmp(hex_code, "0000", 4))
            {
                s.push_back(0);
                return ReturnType(true);
            }
            UInt16 code_point = unhex4(hex_code);
            if (code_point <= 0x7F)
            {
                s.push_back(code_point);
            }
            else if (code_point <= 0x07FF)
            {
                s.push_back(((code_point >> 6) & 0x1F) | 0xC0);
                s.push_back((code_point & 0x3F) | 0x80);
            }
            else
            {
                
                if (code_point >= 0xD800 && code_point <= 0xDBFF)
                {
                    if (!checkString("\\u", buf))
                        return error("Cannot parse escape sequence: missing second part of surrogate pair", ErrorCodes::CANNOT_PARSE_ESCAPE_SEQUENCE);
                    char second_hex_code[4];
                    if (4 != buf.read(second_hex_code, 4))
                        return error("Cannot parse escape sequence: less than four bytes after \\u of second part of surrogate pair",
                            ErrorCodes::CANNOT_PARSE_ESCAPE_SEQUENCE);