bug: Alias for Option Causes "Invalid path" Error in match

[0xNeshi]

Bug Report

Cairo version:

scarb 2.9.2+nightly-2024-12-22 (29eda693a 2024-12-22)
cairo: 2.9.2 (b356014ef)
sierra: 1.6.0

Current behavior:

When setting an alias for Option, like:

type OptAlias<T> = Option<T>;

One is able to assign a value of this alias type using the Alias name like:

let opt_alias: OptAlias<u32> = OptAlias::None;

But matching against this alias using the alias name fails with "Invalid Path":

    let opt_alias: OptAlias<u32> = OptAlias::None;
    match opt_alias {
        OptAlias::None => println!("opt_alias is None"), // Error: Invalid path.
        OptAlias::Some(val) => println!("opt_alias is Some({val})"), // Error: Invalid path.
    }

Instead, one has to use Option directly:

    let opt_alias: OptAlias<u32> = OptAlias::None;
    match opt_alias {
        Option::None => println!("opt_alias is None"), // works
        Option::Some(val) => println!("opt_alias is Some({val})"), // works
    }

Expected behavior:

One should be able to use alias name in the match.

Steps to reproduce:

• create new project
• open lib.cairo
• copy/paste the below related code into it
• compile
• expected: compile successful
• actual: compilation fails with "Invalid path."

Related code:

type OptAliasU32 = Option<u32>;

type OptAlias<T> = Option<T>;

fn main() {
    let opt: Option<u32> = Option::None;
    match opt {
        Option::None => println!("opt is None"),
        Option::Some(val) => println!("opt is Some({val})"),
    }

    let opt_alias: OptAliasU32 = OptAliasU32::None;
    match opt_alias {
        Option::None => println!("opt_alias is None"), // works
        Option::Some(val) => println!("opt_alias is Some({val})"), // works
    }

    let opt_alias: OptAlias<u32> = OptAlias::None;
    match opt_alias {
        Option::None => println!("opt_alias is None"), // works
        Option::Some(val) => println!("opt_alias is Some({val})"), // works
    }

    let opt_alias: OptAliasU32 = OptAliasU32::None;
    match opt_alias {
        OptAliasU32::None => println!("opt_alias is None"), // Invalid path.
        OptAliasU32::Some(val) => println!("opt_alias is Some({val})"), // Invalid path.
    }

    let opt_alias: OptAlias<u32> = OptAlias::None;
    match opt_alias {
        OptAlias::None => println!("opt_alias is None"), // Invalid path.
        OptAlias::Some(val) => println!("opt_alias is Some({val})"), // Invalid path.
    }
}

Other information: