Repository navigation
Suggest enclosing {:?}/{:#?}/{} in "" when used as a format argument #155508
Description
Code
#[derive(Debug)]
enum UwU {
QwQ, AwA, QAQ,
}
fn main() {
println!({:?}, UwU::QwQ)
}Current output
error: expected expression, found `:`
--> src/main.rs:7:15
|
7 | println!({:?}, UwU::QwQ)
| ^ expected expression
|
help: maybe write a path separator here
|
7 | println!({::?}, UwU::QwQ)
| +
error: format argument must be a string literal
--> src/main.rs:7:14
|
7 | println!({:?}, UwU::QwQ)
| ^^^^
|
help: you might be missing a string literal to format with
|
7 | println!("{} {}", {:?}, UwU::QwQ)
| ++++++++
error: could not compile `playground` (bin "playground") due to 2 previous errorsDesired output
error: expected expression, found `:`
--> src/main.rs:7:15
|
7 | println!({:?}, UwU::QwQ)
| ^ expected expression
|
help: maybe write a path separator here
|
7 | println!({::?}, UwU::QwQ)
| +
error: format argument must be a string literal
--> src/main.rs:7:14
|
7 | println!({:?}, UwU::QwQ)
| ^^^^
|
help: you might be missing a string literal to format with
|
7 | println!("{} {}", {:?}, UwU::QwQ)
| ++++++++
help: you might want to enclose `{:?}` in `""`
|
7 | println!("{:?}", UwU::QwQ)
| ++++++
error: could not compile `playground` (bin "playground") due to 2 previous errorsRationale and extra context
I think this is most likely what users intended when writing something like {}, {:?} or {:#?} in this context, and usually the slight difference between "{:?}" and {:?} is easy to miss at a glance, so I think this suggestion could be helpful.
Other cases
Rust Version
playground 1.97.0-nightly
(2026-04-18 0febdbab2720dc0360cd)Anything else?
No response
Activity
cclfmht commentedon Apr 23, 2026
Hi, I think this would be very helpful and I want to work on this issue.
@rustbot claim
Rollup merge of rust-lang#155693 - cclfmht:fix/issue-155508, r=ShoyuV…
Rollup merge of rust-lang#155693 - cclfmht:fix/issue-155508, r=ShoyuV…
Rollup merge of rust-lang#155693 - cclfmht:fix/issue-155508, r=ShoyuV…
Unrolled build for #155693
Rollup merge of #155693 - cclfmht:fix/issue-155508, r=ShoyuVanilla
makai410 commentedon Jun 25, 2026
Hi! @cclfmht Thanks for working on this! I was wondering what's the current status of this issue? Can we close this?
cclfmht commentedon Jun 25, 2026
The issue has been implemented into rustc, so I think it's OK to close it.