Function validate_default_expression 

pub fn validate_default_expression(
    context: &SchemaBindingContext<'_, '_>,
    expression: &mut Expr,
    target: &ColumnType,
    column: &str,
) -> Result<bool, SQLError>

Analyze a default as cookDefault does and bind it for storage. column names the column, or the domain, the default belongs to. Returns whether the default remains: a default that cooks to a NULL constant is dropped, as AddRelationNewConstraints and DefineDomain store no default for it.