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Implement declarative (`macro_rules!`) attribute macros (RFC 3697) by joshtriplett · Pull Request #144579 · rust-lang/rust

@rustbot rustbot added S-waiting-on-review

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Jul 28, 2025

Veykril

fee1-dead

petrochenkov

petrochenkov

Test macros via path and local macros.

@joshtriplett

@joshtriplett

@joshtriplett 

…cursively

This allows a macro attribute to implement default arguments by
reapplying itself with the defaults filled in, for instance.

@joshtriplett

@bors bors added S-waiting-on-bors

Status: Waiting on bors to run and complete tests. Bors will change the label on completion.

and removed S-waiting-on-author

Status: This is awaiting some action (such as code changes or more information) from the author.

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Aug 8, 2025

bors added a commit that referenced this pull request

Aug 8, 2025 
Rollup of 8 pull requests

Successful merges:

 - #139451 (Add `target_env = "macabi"` and `target_env = "sim"`)
 - #144039 (Use `tcx.short_string()` in more diagnostics)
 - #144192 (atomicrmw on pointers: move integer-pointer cast hacks into backend)
 - #144545 (In rustc_pattern_analysis, put `true` witnesses before `false` witnesses)
 - #144579 (Implement declarative (`macro_rules!`) attribute macros (RFC 3697))
 - #144649 (Account for bare tuples and `Pin` methods in field searching logic)
 - #144775 (more strongly dissuade use of `skip_binder`)
 - #144987 (Enable f16 and f128 on targets that were fixed in LLVM21)

r? `@ghost`
`@rustbot` modify labels: rollup

rust-timer added a commit that referenced this pull request

Aug 9, 2025 
Rollup merge of #144579 - joshtriplett:mbe-attr, r=petrochenkov

Implement declarative (`macro_rules!`) attribute macros (RFC 3697)

This implements [RFC 3697](#143547), "Declarative (`macro_rules!`) attribute macros".

I would suggest reading this commit-by-commit. This first introduces the
feature gate, then adds parsing for attribute rules (doing nothing with them),
then adds the ability to look up and apply `macro_rules!` attributes by path,
then adds support for local attributes, then adds a test, and finally makes
various improvements to errors.

github-actions bot pushed a commit to rust-lang/miri that referenced this pull request

Aug 9, 2025

@bors

github-actions bot pushed a commit to model-checking/verify-rust-std that referenced this pull request

Aug 12, 2025 
Rollup of 8 pull requests

Successful merges:

 - rust-lang#139451 (Add `target_env = "macabi"` and `target_env = "sim"`)
 - rust-lang#144039 (Use `tcx.short_string()` in more diagnostics)
 - rust-lang#144192 (atomicrmw on pointers: move integer-pointer cast hacks into backend)
 - rust-lang#144545 (In rustc_pattern_analysis, put `true` witnesses before `false` witnesses)
 - rust-lang#144579 (Implement declarative (`macro_rules!`) attribute macros (RFC 3697))
 - rust-lang#144649 (Account for bare tuples and `Pin` methods in field searching logic)
 - rust-lang#144775 (more strongly dissuade use of `skip_binder`)
 - rust-lang#144987 (Enable f16 and f128 on targets that were fixed in LLVM21)

r? `@ghost`
`@rustbot` modify labels: rollup

Kobzol pushed a commit to Kobzol/rustc_codegen_gcc that referenced this pull request

Dec 21, 2025

Kobzol pushed a commit to Kobzol/rustc_codegen_cranelift that referenced this pull request

Dec 29, 2025

christian-schilling pushed a commit to christian-schilling/rustc_codegen_cranelift that referenced this pull request

Jan 27, 2026

christian-schilling pushed a commit to christian-schilling/rustc_codegen_cranelift that referenced this pull request

Jan 27, 2026