Tracking issue for deprecation lint legacy_derive_helpers
#79202
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A-lint
Area: Lints (warnings about flaws in source code) such as unused_mut.
A-macros
Area: All kinds of macros (custom derive, macro_rules!, proc macros, ..)
C-tracking-issue
Category: A tracking issue for an RFC or an unstable feature.
S-tracking-ready-to-stabilize
Status: This is ready to stabilize; it may need a stabilization report and a PR
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Relevant to the compiler team, which will review and decide on the PR/issue.
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expand/resolve: Turn `#[derive]` into a regular macro attribute This PR turns `#[derive]` into a regular attribute macro declared in libcore and defined in `rustc_builtin_macros`, like it was previously done with other "active" attributes in rust-lang#62086, rust-lang#62735 and other PRs. This PR is also a continuation of rust-lang#65252, rust-lang#69870 and other PRs linked from them, which layed the ground for converting `#[derive]` specifically. `#[derive]` still asks `rustc_resolve` to resolve paths inside `derive(...)`, and `rustc_expand` gets those resolution results through some backdoor (which I'll try to address later), but otherwise `#[derive]` is treated as any other macro attributes, which simplifies the resolution-expansion infra pretty significantly. The change has several observable effects on language and library. Some of the language changes are **feature-gated** by [`feature(macro_attributes_in_derive_output)`](rust-lang#81119). #### Library - `derive` is now available through standard library as `{core,std}::prelude::v1::derive`. #### Language - `derive` now goes through name resolution, so it can now be renamed - `use derive as my_derive; #[my_derive(Debug)] struct S;`. - `derive` now goes through name resolution, so this resolution can fail in corner cases. Crater found one such regression, where import `use foo as derive` goes into a cycle with `#[derive(Something)]`. - **[feature-gated]** `#[derive]` is now expanded as any other attributes in left-to-right order. This allows to remove the restriction on other macro attributes following `#[derive]` (rust-lang/reference#566). The following macro attributes become a part of the derive's input (this is not a change, non-macro attributes following `#[derive]` were treated in the same way previously). - `#[derive]` is now expanded as any other attributes in left-to-right order. This means two derive attributes `#[derive(Foo)] #[derive(Bar)]` are now expanded separately rather than together. It doesn't generally make difference, except for esoteric cases. For example `#[derive(Foo)]` can now produce an import bringing `Bar` into scope, but previously both `Foo` and `Bar` were required to be resolved before expanding any of them. - **[feature-gated]** `#[derive()]` (with empty list in parentheses) actually becomes useful. For historical reasons `#[derive]` *fully configures* its input, eagerly evaluating `cfg` everywhere in its target, for example on fields. Expansion infra doesn't do that for other attributes, but now when macro attributes attributes are allowed to be written after `#[derive]`, it means that derive can *fully configure* items for them. ```rust #[derive()] #[my_attr] struct S { #[cfg(FALSE)] // this field in removed by `#[derive()]` and not observed by `#[my_attr]` field: u8 } ``` - `#[derive]` on some non-item targets is now prohibited. This was accidentally allowed as noop in the past, but was warned about since early 2018 (rust-lang#50092), despite that crater found a few such cases in unmaintained crates. - Derive helper attributes used before their introduction are now reported with a deprecation lint. This change is long overdue (since macro modularization, rust-lang#52226 (comment)), but it was hard to do without fixing expansion order for derives. The deprecation is tracked by rust-lang#79202. ```rust #[trait_helper] // warning: derive helper attribute is used before it is introduced #[derive(Trait)] struct S {} ``` Crater analysis: rust-lang#79078 (comment)
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7644: Primitive completion r=jonas-schievink a=jonas-schievink Fixes #7642 7648: fix nightly warning `legacy_derive_helpers` r=jonas-schievink a=peddermaster2 With a recent nightly (e.g. 2021-02-10) a warning comes up. This PR reorders the attributes to fix the warning. See rust-lang/rust#79202 Co-authored-by: Jonas Schievink <[email protected]> Co-authored-by: Peter Wischer <[email protected]>
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7648: fix nightly warning `legacy_derive_helpers` r=jonas-schievink a=peddermaster2 With a recent nightly (e.g. 2021-02-10) a warning comes up. This PR reorders the attributes to fix the warning. See rust-lang/rust#79202 Co-authored-by: Peter Wischer <[email protected]>
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7638: libloading 0.7 r=kjeremy a=kjeremy See https://docs.rs/libloading/0.7.0/libloading/changelog/r0_7_0/index.html 7648: fix nightly warning `legacy_derive_helpers` r=lnicola a=peddermaster2 With a recent nightly (e.g. 2021-02-10) a warning comes up. This PR reorders the attributes to fix the warning. See rust-lang/rust#79202 Co-authored-by: kjeremy <[email protected]> Co-authored-by: Peter Wischer <[email protected]>
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Sort inert attributes after the derive. rust-lang/rust#79202
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265: Fix nightly warning legacy_derive_helpers r=jonasbb a=jonasbb Sort inert attributes after the derive. rust-lang/rust#79202 bors r+ Co-authored-by: Jonas Bushart <[email protected]>
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This does not (yet) upgrade ./rust-toolchain The warnings: * dead_code "field is never read" * redundant_semicolons "unnecessary trailing semicolon" * non_fmt_panic "panic message is not a string literal, this is no longer accepted in Rust 2021" * unstable_name_collisions "a method with this name may be added to the standard library in the future" * legacy_derive_helpers "derive helper attribute is used before it is introduced" rust-lang/rust#79202
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This does not (yet) upgrade ./rust-toolchain The warnings: * dead_code "field is never read" * redundant_semicolons "unnecessary trailing semicolon" * non_fmt_panic "panic message is not a string literal, this is no longer accepted in Rust 2021" * unstable_name_collisions "a method with this name may be added to the standard library in the future" * legacy_derive_helpers "derive helper attribute is used before it is introduced" rust-lang/rust#79202
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Feb 25, 2021
This does not (yet) upgrade ./rust-toolchain The warnings: * dead_code "field is never read" * redundant_semicolons "unnecessary trailing semicolon" * non_fmt_panic "panic message is not a string literal, this is no longer accepted in Rust 2021" * unstable_name_collisions "a method with this name may be added to the standard library in the future" * legacy_derive_helpers "derive helper attribute is used before it is introduced" rust-lang/rust#79202
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This does not (yet) upgrade ./rust-toolchain The warnings: * dead_code "field is never read" * redundant_semicolons "unnecessary trailing semicolon" * non_fmt_panic "panic message is not a string literal, this is no longer accepted in Rust 2021" * unstable_name_collisions "a method with this name may be added to the standard library in the future" * legacy_derive_helpers "derive helper attribute is used before it is introduced" rust-lang/rust#79202
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Feb 25, 2021
This fixes Nightly warnings See rust-lang/rust#79202
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1237: Move `#[error]` attributes after the corresponding `#[derive]` r=kvark a=Aaron1011 **Connections** See rust-lang/rust#79202 **Description** Fixes Nightly future-incompat warnings **Testing** There are no behavior changes intended. Co-authored-by: Aaron Hill <[email protected]>
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Mar 14, 2021
In particular, this takes care of rust-lang/rust#79202 as well as some clippy nightly suggestions. There is a new very noisy https://rust-lang.github.io/rust-clippy/master/index.html#upper_case_acronyms but I didn’t take care of that one.
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In particular, this takes care of rust-lang/rust#79202 as well as some clippy nightly suggestions. There is a new very noisy https://rust-lang.github.io/rust-clippy/master/index.html#upper_case_acronyms but I didn’t take care of that one.
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On current nightly, this fixes a warning:
error: derive helper attribute is used before it is introduced
It goes on to say
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #79202 <rust-lang/rust#79202>
This change gets ahead of the issue.
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this is deprecated with rustc 1.52+, and will become a hard error at some point: rust-lang/rust#79202 Signed-off-by: Fabian Grünbichler <[email protected]>
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These will become hard errors in the future See <rust-lang/rust#79202>
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These will become hard errors in the future See <rust-lang/rust#79202> Co-authored-by: Alyssa Ingersoll <[email protected]>
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Bug: rust-lang/rust#79202 Signed-off-by: Matthew [email protected]
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See rust#79202 <rust-lang/rust#79202> Signed-off-by: Luca Barbato <[email protected]>
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See rust#79202 <rust-lang/rust#79202> Closes: #9 Signed-off-by: Georgy Yakovlev <[email protected]>
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* Updated results viewer dependencies and fixed sed command * Added sed fix to update-guild.yml * Added tests for the hdr-histogram-wasm * Updated dependencies for config-wasm tests * Updated the comment to show that wasm-pack v0.10.0 works * Renamed tests directory to match config directory * Renamed config_wasm to config-wasm to match hdr-histogram-wasm * Updated the mdbook and wasm-pack versions in the Dockerfile * Updated the workflows - Updated the mdbook and wasm-pack versions - Updated pr and release to build both config-wasm and hdr-histogram-wasm and run tests * Updated the lock file to the latest dependencies * Fixed warning in latest version of Rust rust-lang/rust#79202 * Changed the config-wasm and hdr-histogram-wasm to be scoped '@fs' * extraneous spaces from empty lines * Fixed the names in the Javascript PR workflow * Initial fixes for clippy (failing tests) * Updated babel version
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## Motivation and Context Follow-up to #2434 ## Description This provides a way to fix a compiler warning. Attributes created using RustMetadata.additionalAttributes may trigger compiler warnings (rust-lang/rust#79202) such as ``` warning: derive helper attribute is used before it is introduced --> src/model.rs:7674:3 | 7674 | #[serde(tag = "_type", content = "_content")] | ^^^^^ 7675 | #[derive( 7676 | serde::Deserialize, | ------------------ the attribute is introduced here | = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! = note: for more information, see issue #79202 <rust-lang/rust#79202> ``` ## Testing Added a unit test to validate the sort order is applied correctly to Attributes with isDeriveHelper = true. --------- Co-authored-by: david-perez <[email protected]>
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## Motivation and Context Follow-up to #2434 ## Description This provides a way to fix a compiler warning. Attributes created using RustMetadata.additionalAttributes may trigger compiler warnings (rust-lang/rust#79202) such as ``` warning: derive helper attribute is used before it is introduced --> src/model.rs:7674:3 | 7674 | #[serde(tag = "_type", content = "_content")] | ^^^^^ 7675 | #[derive( 7676 | serde::Deserialize, | ------------------ the attribute is introduced here | = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! = note: for more information, see issue #79202 <rust-lang/rust#79202> ``` ## Testing Added a unit test to validate the sort order is applied correctly to Attributes with isDeriveHelper = true. --------- Co-authored-by: david-perez <[email protected]>
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## Motivation and Context Follow-up to #2434 ## Description This provides a way to fix a compiler warning. Attributes created using RustMetadata.additionalAttributes may trigger compiler warnings (rust-lang/rust#79202) such as ``` warning: derive helper attribute is used before it is introduced --> src/model.rs:7674:3 | 7674 | #[serde(tag = "_type", content = "_content")] | ^^^^^ 7675 | #[derive( 7676 | serde::Deserialize, | ------------------ the attribute is introduced here | = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! = note: for more information, see issue #79202 <rust-lang/rust#79202> ``` ## Testing Added a unit test to validate the sort order is applied correctly to Attributes with isDeriveHelper = true. --------- Co-authored-by: david-perez <[email protected]>
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This issue hasn't been referred to in over half a year, and only sparingly before that. We may want to try out making this a hard error |
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Rust 1.52 added a legacy_derive_helpers warning (soon to be an error) that yells if you use an attribute macro before the derive macro that introduces it. We should always put derive macros at the start of the list to avoid this. Reference: rust-lang/rust#79202
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This is a tracking issue for deprecating code like this:
Code like this works for historical reasons, but attribute expansion works in left-to-right order, so we have to use some hacks and "look into the future" to resolve
trait_helper, but that future may never actually happen in cases like, so the resolution in this case is unreliable.
A deprecation lint for this case is added in #79078 as warn-by-default.
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