warning: custom classes in code blocks will change behaviour
  --> $DIR/feature-gate-custom_code_classes_in_docs.rs:3:1
   |
LL | / /// ```{class=language-c}
LL | | /// int main(void) { return 0; }
LL | | /// ```
   | |_______^
   |
   = note: see issue #79483 <https://github.com/rust-lang/rust/issues/79483> for more information
   = help: add `#![feature(custom_code_classes_in_docs)]` to the crate attributes to enable
   = note: found these custom classes: class=language-c

warning: 1 warning emitted