Add Wasm platform aware test to export proc-macro

Author: Daniel Salinas

bindings/matrix-sdk-ffi-macros/src/lib.rs

@@ -51,7 +51,12 @@ pub fn export(attr: TokenStream, item: TokenStream) -> TokenStream {
 
     let res = match syn::parse(item) {
         Ok(item) => match has_async_fn(item) {
-            true => quote! { #[uniffi::export(async_runtime = "tokio", #attr2)] },
+            true => {
+                quote! {
+                  #[cfg_attr(target_family = "wasm", uniffi::export(#attr2))]
+                  #[cfg_attr(not(target_family = "wasm"), uniffi::export(async_runtime = "tokio", #attr2))]
+                }
+            }
             false => quote! { #[uniffi::export(#attr2)] },
         },
         Err(e) => e.into_compile_error(),