Macro batch_impl_fill 

batch_impl_fill!() { /* proc-macro */ }

Documentation placeholder for the #fill directive.

#fill(args){body} copies each selected trait item’s signature and substitutes body as its implementation. Selection supports the @all families (@all_methods, @all_ref_methods, @all_default_methods, …), individual names, and - subtraction (#fill(@all_methods, -foo)).

#[batch_impl(Vec<u32> #fill(@all_methods){0})]
trait F { fn zero(&self) -> u32; }

Documentation marker only — never call this function.