This is a tracking issue for the RFC "Declarative macro_rules! derive macros" (rust-lang/rfcs#3698).
The feature gate for the issue is #![feature(macro_derive)].
About tracking issues
Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.
Discussion comments will get marked as off-topic or deleted.
Repeated discussions on the tracking issue may lead to the tracking issue getting locked.
Steps
Unresolved Questions
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Before stabilizing this feature, we should ensure there's a mechanism macros can use to ensure that an error when producing an impl does not result in a cascade of additional errors caused by a missing impl. This may take the form of a fallback impl, for instance.
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Before stabilizing this feature, we should make sure it doesn't produce wildly worse error messages in common cases.
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Before stabilizing this feature, we should receive feedback from crate maintainers, and potentially make further improvements to macro_rules to make it easier to use for their use cases. This feature will provide motivation to evaluate many new use cases that previously weren't written using macro_rules, and we should consider quality-of-life improvements to better support those use cases.
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Before stabilizing this feature, we should have clear public guidance recommending against pressuring crate maintainers to adopt this feature rapidly, and encourage crate maintainers to link to that guidance if such requests arise.
Implementation history
This is a tracking issue for the RFC "Declarative
macro_rules!derive macros" (rust-lang/rfcs#3698).The feature gate for the issue is
#![feature(macro_derive)].About tracking issues
Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.
Discussion comments will get marked as off-topic or deleted.
Repeated discussions on the tracking issue may lead to the tracking issue getting locked.
Steps
macro_rules!) derive macros (RFC 3698) #145208)rustfmtUnresolved Questions
Before stabilizing this feature, we should ensure there's a mechanism macros can use to ensure that an error when producing an impl does not result in a cascade of additional errors caused by a missing impl. This may take the form of a fallback impl, for instance.
Before stabilizing this feature, we should make sure it doesn't produce wildly worse error messages in common cases.
Before stabilizing this feature, we should receive feedback from crate maintainers, and potentially make further improvements to
macro_rulesto make it easier to use for their use cases. This feature will provide motivation to evaluate many new use cases that previously weren't written usingmacro_rules, and we should consider quality-of-life improvements to better support those use cases.Before stabilizing this feature, we should have clear public guidance recommending against pressuring crate maintainers to adopt this feature rapidly, and encourage crate maintainers to link to that guidance if such requests arise.
Implementation history