struct literal syntax does not work with custom dialect

[universalmind303]

The following should work, but instead fails with Expected an expression:, found: { at Line: 1, Column 8

use sqlparser::dialect::Dialect;

#[derive(Debug)]
pub struct MyDialect;
impl Dialect for MyDialect {
    fn is_identifier_start(&self, ch: char) -> bool {
        ch.is_alphabetic() || ch == '_'
    }

    fn is_identifier_part(&self, ch: char) -> bool {
        ch.is_alphabetic() || ch.is_ascii_digit() || ch == '$' || ch == '_'
    }

    fn supports_filter_during_aggregation(&self) -> bool {
        true
    }

    fn supports_group_by_expr(&self) -> bool {
        true
    }

    fn supports_named_fn_args_with_eq_operator(&self) -> bool {
        true
    }
}

fn main() {
    let sql = "select {'a': 1}";
    let dialect = MyDialect;
    let parser = sqlparser::parser::Parser::new(&dialect);
    assert!(parser.try_with_sql(sql).unwrap().parse_statement().is_ok());
}

[universalmind303]

FWIW, it seems like this is due to the usage of dialect_of! throughout the parser code.

It seems like either the dialect itself needs to be in control of supported syntaxes, or a custom dialect should just be treated as an extension of GenericDialect.

I think the latter would be a bit easier as dialect_of is used ~100 times, so that would be a lot of functionality to expose to the Dialect trait.

[universalmind303]

Looking more closely at the code, it looks like you can "extend" a dialect by implementing the Dialect::dialect method

impl Dialect for MyDialect {
    fn dialect(&self) -> std::any::TypeId {
        std::any::TypeId::of::<sqlparser::dialect::GenericDialect>()
    }