Derives on deprecated items generate deprecation warnings

The following code generates a warning on nightly and beta but not on stable:

#[deprecated = "oh no"]
#[derive(Default)]
struct X;

Hmm; technically generating warnings seems like correct but annoying behavior (which we don't have to fix but probably should...). Putting #[allow(deprecated)] on generated impls seems like a solution?

This regression also breaks existing code with #[deny(warnings)].

derive attributes can only be put on the type but the same people than the ones who control the deprecated attribute, so I don't see how that's technically correct. Derives should only ever generate a deprecated warning if the trait they derive is deprecated, never because of the type's deprecatedness.

Just hit this in servo...

warning: use of deprecated item 'vr_display_capabilities::VRDisplayCapabilities::presented_by_browser': please use `future_frame_data` instead
 --> /Users/ajeffrey/github/asajeffrey/rust-webvr/rust-webvr-api/src/vr_display_capabilities.rs:3:52
  |
3 | #[cfg_attr(feature = "serde-serialization", derive(Deserialize, Serialize))]
  |                                                    ^^^^^^^^^^^
  |
  = note: #[warn(deprecated)] on by default

warning: use of deprecated item 'vr_display_capabilities::VRDisplayCapabilities::presented_by_browser': please use `future_frame_data` instead
 --> /Users/ajeffrey/github/asajeffrey/rust-webvr/rust-webvr-api/src/vr_display_capabilities.rs:3:52
  |
3 | #[cfg_attr(feature = "serde-serialization", derive(Deserialize, Serialize))]
  |                                                    ^^^^^^^^^^^

warning: use of deprecated item 'vr_display_capabilities::VRDisplayCapabilities::presented_by_browser': please use `future_frame_data` instead
 --> /Users/ajeffrey/github/asajeffrey/rust-webvr/rust-webvr-api/src/vr_display_capabilities.rs:3:65
  |
3 | #[cfg_attr(feature = "serde-serialization", derive(Deserialize, Serialize))]
  |                                                                 ^^^^^^^^^

Caused by deprecating a field in a struct.

Just hit this in Mundane too. We #![deny(warnings)], so it causes compilation failure.

error: use of deprecated item 'hash::InsecureSha1': SHA-1 is considered insecure
   --> src/hash.rs:102:10
    |
102 | #[derive(Default)]
    |          ^^^^^^^
    |
note: lint level defined here
   --> src/lib.rs:45:9
    |
45  | #![deny(warnings)]
    |         ^^^^^^^^
    = note: #[deny(deprecated)] implied by #[deny(warnings)]

error: use of deprecated item 'hash::InsecureSha1': SHA-1 is considered insecure
   --> src/hash.rs:102:10
    |
102 | #[derive(Default)]
    |          ^^^^^^^

error: use of deprecated item 'hash::InsecureSha1': SHA-1 is considered insecure
   --> src/hash.rs:102:10
    |
102 | #[derive(Default)]
    |          ^^^^^^^
    |
note: lint level defined here
   --> src/lib.rs:45:9
    |
45  | #![deny(warnings)]
    |         ^^^^^^^^
    = note: #[deny(deprecated)] implied by #[deny(warnings)]

error: use of deprecated item 'hash::InsecureSha1': SHA-1 is considered insecure
   --> src/hash.rs:102:10
    |
102 | #[derive(Default)]
    |          ^^^^^^^

error: use of deprecated item 'hash::InsecureSha1::ctx': SHA-1 is considered insecure
   --> src/hash.rs:104:5
    |
104 |     ctx: CStackWrapper<boringssl::SHA_CTX>,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

triage: P-high

I'm currently running a bisection with cargo-bisect-rustc.

@oli-obk

Regression is tracked to c84e797, which is #58098, cc @oli-obk -- this PR is titled " Require a list of features in #[allow_internal_unstable] #58098 ", one can certainly imagine how it could be related to this problem, perhaps the list of "allowed unstable features" for derives simply needs to be extended?

@oli-obk

speculatively assigning to @oli-obk based on @nikomatsakis 's bisection.

This is definitely caused by this change. We used to just not emit deprecation warnings inside allow_internal_unstable code. I'll extend derives to add #[allow(deprecated)] to replicate the previous behaviour, but we should probably create something more fine grained some day.

Navigation Menu

Repository navigation

Derives on deprecated items generate deprecation warnings #58822

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Derives on deprecated items generate deprecation warnings #58822

Description

Activity

Centril commented on Feb 28, 2019

joshlf commented on Mar 1, 2019

nox commented on Mar 5, 2019

asajeffrey commented on Mar 5, 2019

joshlf commented on Mar 6, 2019

pnkfelix commented on Mar 7, 2019

nikomatsakis commented on Mar 7, 2019

nikomatsakis commented on Mar 7, 2019

pnkfelix commented on Mar 7, 2019

oli-obk commented on Mar 7, 2019

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions