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Use E0665 for missing #[default] on enum and update doc#134364

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Dec 22, 2024
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Use E0665 for missing #[default] on enum and update doc#134364
bors merged 2 commits intorust-lang:masterfrom
estebank:derive-docs

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@estebank estebank commented Dec 16, 2024 •
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The docs for E0665 when doing #[derive(Default] on an enum previously didn't mention #[default] at all, or made a distinction between unit variants, that can be annotated, and tuple or struct variants, which cannot.

E0665 was not being emitted, we now use it for the same error it belonged to before.

error[E0665]: `#[derive(Default)]` on enum with no `#[default]`
  --> $DIR/macros-nonfatal-errors.rs:42:10
   |
LL |   #[derive(Default)]
   |            ^^^^^^^
LL | / enum NoDeclaredDefault {
LL | |     Foo,
LL | |     Bar,
LL | | }
   | |_- this enum needs a unit variant marked with `#[default]`
   |
   = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)
help: make this unit variant default by placing `#[default]` on it
   |
LL |     #[default] Foo,
   |     ++++++++++
help: make this unit variant default by placing `#[default]` on it
   |
LL |     #[default] Bar,
   |     ++++++++++

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compiler/rustc_error_codes/src/error_codes/E0665.md
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This error code is no longer emitted by the compiler and I don't see the point in updating this entry if it no longer sees the light of day (ignoring the use of old rustc verions & subsequent exposure via the website).

The diagnostic which gets currently emitted on a #[derive(Default)] enum without #[default] doesn't have any error code associated with it. I don't know why it didn't take over E0665. If you make it use E0665 (I think that makes sense), then I'm fine with updating this entry.

@fmease fmease added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 16, 2024
@estebank estebank added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Dec 21, 2024
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Thanks, this diagnostic and the error index entry is now so much better!

r=me after nits & CI failure addressed and title change

estebank
estebank commented Dec 21, 2024
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compiler/rustc_error_codes/src/error_codes/E0665.md Outdated
Erroneous code example:

```compile_fail
```compile_fail,ignore
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I had to do this to get over the stage0 test of this page.

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Doesn't the following make this work?

```compile_fail,E0665

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@estebank
Use E0665 for missing #[default] error
94812f1 
Use orphaned error code for the same error it belonged to before.

```
error[E0665]: `#[derive(Default)]` on enum with no `#[default]`
  --> $DIR/macros-nonfatal-errors.rs:42:10
   |
LL |   #[derive(Default)]
   |            ^^^^^^^
LL | / enum NoDeclaredDefault {
LL | |     Foo,
LL | |     Bar,
LL | | }
   | |_- this enum needs a unit variant marked with `#[default]`
   |
   = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)
help: make this unit variant default by placing `#[default]` on it
   |
LL |     #[default] Foo,
   |     ~~~~~~~~~~~~~~
help: make this unit variant default by placing `#[default]` on it
   |
LL |     #[default] Bar,
   |     ~~~~~~~~~~~~~~
```
@estebank estebank changed the title Mention #[default] in E0655 code index Use E0665 for missing #[default] on enum and update doc Dec 21, 2024
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estebank commented Dec 21, 2024

@bors r=fmease

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bors commented Dec 21, 2024

📌 Commit 94812f1 has been approved by fmease

It is now in the queue for this repository.

@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-review Status: Awaiting review from the assignee but also interested parties. labels Dec 21, 2024
@matthiaskrgr matthiaskrgr mentioned this pull request Dec 22, 2024
Merged
bors added a commit to rust-lang-ci/rust that referenced this pull request Dec 22, 2024
@bors
Auto merge of rust-lang#134640 - matthiaskrgr:rollup-xlstm3o, r=matth…
a2bcfae 
…iaskrgr

Rollup of 6 pull requests

Successful merges:

 - rust-lang#134364 (Use E0665 for missing `#[default]` on enum and update doc)
 - rust-lang#134601 (Support pretty-printing `dyn*` trait objects)
 - rust-lang#134603 (Explain why a type is not eligible for `impl PointerLike`.)
 - rust-lang#134618 (coroutine_clone: add comments)
 - rust-lang#134630 (Use `&raw` for `ptr` primitive docs)
 - rust-lang#134637 (Flatten effects directory now that it doesn't really test anything specific)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 3a94f4c into rust-lang:master Dec 22, 2024
@rustbot rustbot added this to the 1.85.0 milestone Dec 22, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Dec 22, 2024
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Unrolled build for rust-lang#134364
5bc0dd3 
Rollup merge of rust-lang#134364 - estebank:derive-docs, r=fmease

Use E0665 for missing `#[default]` on enum and update doc

The docs for E0665 when doing `#[derive(Default]` on an `enum` previously didn't mention `#[default]` at all, or made a distinction between unit variants, that can be annotated, and tuple or struct variants, which cannot.

E0665 was not being emitted, we now use it for the same error it belonged to before.

```
error[E0665]: `#[derive(Default)]` on enum with no `#[default]`
  --> $DIR/macros-nonfatal-errors.rs:42:10
   |
LL |   #[derive(Default)]
   |            ^^^^^^^
LL | / enum NoDeclaredDefault {
LL | |     Foo,
LL | |     Bar,
LL | | }
   | |_- this enum needs a unit variant marked with `#[default]`
   |
   = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)
help: make this unit variant default by placing `#[default]` on it
   |
LL |     #[default] Foo,
   |     ++++++++++
help: make this unit variant default by placing `#[default]` on it
   |
LL |     #[default] Bar,
   |     ++++++++++
```
github-actions bot pushed a commit to tautschnig/verify-rust-std that referenced this pull request Mar 11, 2025
@bors
Auto merge of rust-lang#134640 - matthiaskrgr:rollup-xlstm3o, r=matth…
062ca74 
…iaskrgr

Rollup of 6 pull requests

Successful merges:

 - rust-lang#134364 (Use E0665 for missing `#[default]` on enum and update doc)
 - rust-lang#134601 (Support pretty-printing `dyn*` trait objects)
 - rust-lang#134603 (Explain why a type is not eligible for `impl PointerLike`.)
 - rust-lang#134618 (coroutine_clone: add comments)
 - rust-lang#134630 (Use `&raw` for `ptr` primitive docs)
 - rust-lang#134637 (Flatten effects directory now that it doesn't really test anything specific)

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