attribute macro has no access to attributes defined before it

[roignpar]

Hi! Thank you for syn and all your Rust work!

I ran into this issue while debugging this: roignpar/optfield#4
It seems that attribute macros have no access to attrs defined before them.

#[before]
#[after]
struct Item;

If both before and after are attribute macros:

• before will have after in Item's attrs field
• after will not have before in Item's attrs field

The same happens with any kind of attribute in relation to attribute macros.

I haven't tried this with other proc macro types.

Most documentation I could find was here: https://doc.rust-lang.org/reference/procedural-macros.html#attribute-macros, but it says that "The second TokenStream is the rest of the item including other attributes on the item."
I couldn't find any mention of attribute order or anything like that.

Is this intended behavior?

[dtolnay]

This issue is not related to syn. Syn is not in control of what tokens rustc passes into an attribute macro.