[Sqlalchemy-tickets] Issue #4336: BooleanClauseList.compare fails when an expression uses func.cast (zzzeek/sqlalchemy)

[miso <iss...@bi...>]

New issue 4336: BooleanClauseList.compare fails when an expression uses func.cast
https://bitbucket.org/zzzeek/sqlalchemy/issues/4336/booleanclauselistcompare-fails-when-an

miso:

Hello.

I am using the method [compare](https://docs.sqlalchemy.org/en/latest/core/sqlelement.html?highlight=compare#sqlalchemy.sql.expression.ClauseList.compare) of some classes to perform unit test on a function that creates query expressions dynamically.

Two identical expressions fail to compare when **func.cast** is used, even when their string representations are exactly the same.

Here I am leaving a script to test this issue. In the last line, the compare method returns **False**.

```
#!python

from sqlalchemy import func, Column, Integer, String, Text
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.sql.expression import or_

Base = declarative_base()


class Cartoon(Base):
    __tablename__ = 'cartoon'

    id = Column(Integer, primary_key=True)
    name = Column(String)
    nickname = Column(String)
    age = Column(Integer)


# Create two identical expressions
A = or_(Cartoon.name.ilike('%black%'), Cartoon.nickname.ilike('%black%'))
B = or_(Cartoon.name.ilike('%black%'), Cartoon.nickname.ilike('%black%'))

assert str(A) == str(B)  # Ok
assert A.compare(B)  # Ok


# Create two identical expressions using cast
C = or_(Cartoon.name.ilike('%black%'), func.cast(Cartoon.age, Text).ilike('%black%'))
D = or_(Cartoon.name.ilike('%black%'), func.cast(Cartoon.age, Text).ilike('%black%'))

assert str(C) == str(D)  # The string expressions are equal
assert C.compare(D)  # Here the comparison fails
```