"Don't know the field number in this context"

@c410-f3r

src/lib.rs:

struct S(#[attr] u8);

Stable, and nightly-2019-09-09:

error[E0658]: the attribute `attr` is currently unknown to the compiler and may have meaning added to it in the future
 --> src/main.rs:1:10
  |
1 | struct S(#[attr] u8);
  |          ^^^^^^^
  |
  = note: for more information, see https://github.com/rust-lang/rust/issues/29642
  = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

nightly-2019-09-10:

thread 'rustc' panicked at 'don't know the field number in this context', src/librustc/hir/map/def_collector.rs:346:36
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

error: internal compiler error: unexpected panic

note: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.39.0-nightly (0b36e9dea 2019-09-09) running on x86_64-unknown-linux-gnu

note: compiler flags: -C debuginfo=2 -C incremental --crate-type bin

note: some of the compiler flags provided by cargo are hidden

2b8116d...0b36e9d

Mentioning @c410-f3r @petrochenkov because this is likely from #63468.

Yeah, this is some known shortcut taken in #63468, sorry.
Didn't expect people to hit it that fast.
Will fix ~this weekend.

Thanks. The realistic usage where this appears is if you forget to import a derive macro, which happens commonly.

//use serde::Deserialize;

#[derive(Deserialize)]
struct Outer<'a>(#[serde(borrow)] Inner<'a>);

Un-nominating since Vadim self-assigned.

triage: P-high.

Fixed in #64457.

Rollup merge of rust-lang#64457 - petrochenkov:macunfield, r=matthewj…

Updated futures-rs, tokio, tower and rust

Navigation Menu

Repository navigation

"Don't know the field number in this context" #64385

src/lib.rs:

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

"Don't know the field number in this context" #64385

Description

src/lib.rs:

Activity

petrochenkov commented on Sep 11, 2019

dtolnay commented on Sep 11, 2019

Centril commented on Sep 11, 2019

pnkfelix commented on Sep 12, 2019

petrochenkov commented on Sep 14, 2019

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions