A more relaxed "level" of grammar?

[crlf0710]

Sometimes i feel that proc-macros should be given more chance to read and accept "fake" grammars, which allows it accept its own kinds of items and statements. This helps experiments on delegations and virtual structs and ideas like those.

[CAD97]

(Function like) Proc macros already accept an arbitrary token stream, though?

Sure, it is more difficult to parse something that is almost Rust than something that is Rust, as the latter case can just use syn, but anything that can be lexed by the Rust lexer can be accepted by proc macros.

So I don't know exactly what you're asking for. (I am working on a parser generator targeting syn::Parse and proc macros, though, which should make this much easier once it's reasonably usable.)

[Centril]

Is this specifically about procedural attribute macros, which are restricted to valid Rust AST constructs?

[crlf0710]

Is this specifically about procedural attribute macros, which are restricted to valid Rust AST constructs?

Yes, sorry i didn't make it clear.