Support for Macros (Leptos)

Leptos currently uses cfg_if! macros and when having something like

 cfg_if! {
     if #[cfg(feature = "ssr")] {
       // First Main function
        pub fn main() {
            println!("cargo-leptos is not enabled. Please enable it in your Cargo.toml");
        }
    }
    else {
       // Second Main FUnction 
        pub fn main() {
            println!("cargo-leptos is not enabled. Please enable it in your Cargo.toml");
        }
    }
}

it does not support the first one even if i type something random that has no function or anything it will not produce any errors

rust-analyzer version: rust-analyzer version: 0.3.1377-standalone (daa0138e4 2023-01-21)

rustc version: rustc 1.68.0-nightly (0fb8b72ce 2023-01-06)

Start by reproducing the reported Leptos cfg_if! example with the listed rust-analyzer and rustc versions, then compare behavior for the two cfg branches and for invalid code inside the macro. Done means rust-analyzer reports the expected errors and supports both branches in an updated minimal reproduction.