How to treat inert attributes on macro invocations? (original) (raw)

Examples of inert attributes on macro invocations:

#[inert] bang_macro!();

#[inert] #[attr_macro] struct S;

#[inert] #[derive(DeriveMacro)] struct S;

// Doc comments are also attributes (attribute literals if you wish).

/// Doc. bang_macro!();

/// Doc. #[attr_macro] struct S;

/// Doc. #[derive(DeriveMacro)] struct S;

How these attributes are treated currently (ad hoc, there's no RFC or anything):

• For bang macros the attributes are thrown away (sometimes with a warning).
• For attribute macros and derive macros the attributes become a part of the macro input, the attribute tokens are prepended to the tokens of the "primary" input.
  Effectively, #[inert] #[macro_attr] struct S; -> macro_attr! { #[inert] struct S; }.

Related issues: #61733 (comment).