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[Change]: [1.99.0] Stabilize '#[my_macro] mod foo;' - #729
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tshepang merged 2 commits intoOct 2, 2026
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Rust 1.99 stabilizes outline modules (`mod foo;`) in the input of attribute and derive procedural macros (rust-lang/rust#157857). The macro receives the module declaration as tokens; the module's source file is not loaded and its contents are not part of the input.
kirtchev-adacore
approved these changes
Sep 28, 2026
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@tshepang -- would you also like to take a look, before this merges? |
tshepang
requested changes
Sep 29, 2026
Address review feedback on the outline module rules for derive and attribute macro input: - Drop "sole" from the derive rule; the parameter count is already stated by fls_npnze2cg8ae. - State which outline modules the rules cover: for a derive macro, those declared within the related abstract data type; for an attribute macro, the related item itself or a module declared within it. - Fold the no-loading statement into the same sentence instead of a second one. It is kept because excluding the source file contents from the token stream does not by itself say the file is left unloaded, and that is observable: an attribute macro that drops `mod absent;` compiles without the module file existing.
tshepang
approved these changes
Oct 2, 2026
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Summary
Document how attribute and derive macros receive outline module declarations without loading the module files.
Refs #726
Reference alignment
Rust #157857 and Reference #2310. Derive coverage also follows the stabilization tests.