Deprecated attributes do not apply to macro-expanded items

[euclio]

Example at: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=fc72706e6b3151479a1a454611827c50

I expected the deprecation lint to be fired on use of the wrapped function. If this is intentional behavior, I would expect a warning that the deprecated attribute is meaningless in that position.

[Centril]

I believe this is intentional; the attribute is applied to the macro call as opposed to the expansion thereof.

cc @petrochenkov @rust-lang/lang

[petrochenkov]

Yes, attributes applied to macro calls are eliminated during expansion of the macro.
They should be reported as unused or rejected if they have no effect on the macro call itself.

[euclio]

What are the attributes that do have an effect on the macro call? cfg, cfg_attr, and the lint check attributes are the only ones I can think of.

[petrochenkov]

Also, something like #[rustfmt::skip].
(And macro attributes of course, but those are not lost, but rather expanded similarly to cfg and cfg_attr.)

[ocstl]

The deprecated attribute seems to (now) be correctly reported as unused in the example above (as well as for edition 2021: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=f655167d9102a4464f4cc00ee9a181c0).

Is it possible it was overlooked when #50723 was fixed?

[euclio]

I did a quick bisect, and this was fixed by #87296. Closing.