regression: error: path separator must be a double colon (in where clause)

@rustbot

https://crater-reports.s3.amazonaws.com/beta-1.87-rustdoc-2/beta-2025-04-20/gh/wahid122.Rust-tool-testing/log.txt

[INFO] [stdout] error: path separator must be a double colon
[INFO] [stdout]   --> src/lib.rs:68:12
[INFO] [stdout]    |
[INFO] [stdout] 68 |     where a:AsRef<str>{
[INFO] [stdout]    |            ^
[INFO] [stdout]    |
[INFO] [stdout] help: use a double colon instead
[INFO] [stdout]    |
[INFO] [stdout] 68 |     where a::AsRef<str>{
[INFO] [stdout]    |             +

Version it worked on

It most recently worked on: 1.86.0

Version with regression

rustc 1.87.0-beta.5 (386abeb93 2025-04-19) in crater #139827.

@rustbot modify labels: +regression-from-stable-to-beta -regression-untriaged

I minimized it to this example:

pub fn upper<T>() where T:Copy {}
pub fn lower<t>() where t:Copy {}

The upper is fine, but lower gives the error. It's also fine if you add a space, where t: Copy.

On nightly, it also mentions type ascription:

error: path separator must be a double colon
 --> src/lib.rs:2:26
  |
2 | pub fn lower<t>() where t:Copy {}
  |                          ^
  |
  = note: if you meant to annotate an expression with a type, the type ascription syntax has been removed, see issue #101728 <https://github.com/rust-lang/rust/issues/101728>
help: use a double colon instead
  |
2 | pub fn lower<t>() where t::Copy {}
  |                           +

edit: that was with rustc 1.88.0-nightly (78f2104e3 2025-04-16), but not after I updated to 6bc57c6bf 2025-04-22.

Regressed in commit 500a686 (PR #136808)

Also regressed:

fn f<t>(_: impl a<t:u>) {}

trait a { type t; }
trait u {}

To be clear, all of those also warn that you should use CamelCase, but that's a style lint, not a language requirement.

@rustbot

Assigning priority (discussion on Zulip).

@rustbot label -I-prioritize +P-critical

Rollup merge of rust-lang#140228 - fmease:revert-overzealous-colon-re…

Unrolled build for rust-lang#140228

Fixed in #140228.
Backported in #140269.

Navigation Menu

Repository navigation

regression: error: path separator must be a double colon (in `where` clause) #140227

Version it worked on

Version with regression

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

regression: error: path separator must be a double colon (in where clause) #140227

Description

Version it worked on

Version with regression

Activity

cuviper commented on Apr 23, 2025

fmease commented on Apr 23, 2025

fmease commented on Apr 23, 2025

cuviper commented on Apr 23, 2025

apiraino commented on Apr 24, 2025

fmease commented on Apr 28, 2025

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

regression: error: path separator must be a double colon (in `where` clause) #140227