The out_of_scope_macro_calls lint detects macro_rules called when they are not in scope,
above their definition, which may happen in key-value attributes.

Example

#![doc = in_root!()]

macro_rules! in_root { () => { "" } }

fn main() {}

Explanation

The scope in which a macro_rules item is visible starts at that item and continues
below it. This is more similar to let than to other items, which are in scope both above
and below their definition.
Due to a bug macro_rules were accidentally in scope inside some key-value attributes
above their definition. The lint catches such cases.
To address the issue turn the macro_rules into a regularly scoped item by importing it
with use.

Implementation history

• ast: Standardize visiting order for attributes and node IDs #125741 introduced the lint
• out_of_scope_macro_calls: Detect calls inside attributes more precisely #126987 fixed some positives
• Ensure out_of_scope_macro_calls lint is registered #127191 integrated it into the allow/warn/deny infrastructure
• Mark all deprecation lints in name resolution as deny-by-default and report-in-deps #143929 made the lint deny-by-default and report-in-deps
• XXX turned the lint into a hard error