async closure syntax causes compiler error in disabled code block about rust HOT 3 CLOSED

This works as intended. Feature gates for experimental syntax extensions are intentionally run before macro expansion to prevent stable code from relying on it. We promise not to break stable code (with some exceptions ofc). Permitting experimental syntax in “cfg'ed out” code would hinder us to adjust or remove the syntax as stable crates could now fail with syntax errors.

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We have some syntax extensions which still have post-expansion feature gates (which used to be default in the past iirc) like auto_traits. Due to the aforementioned reasons, we can't change the syntax of auto traits anymore (not easily at least).

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Right. Makes sense. Found a workaround using declarative macros since they skip the parser during this phase.

Thanks!

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