Closed
Description
This code is not really something anyone SHOULD write, but because rustc catches it and makes a suggestion, it should either handle it correctly, or not suggest anything at all and give a different warning because it is clearly not something anyone should ever write, and thus it is likely a bug.
let val = 5;
// same issue for all these cases
println!("{:0$}", v = val);
println!("{0:0$}", v = val);
println!("{:0$.0$}", v = val);
println!("{0:0$.0$}", v = val);
// these work correctly, but should probably give a different warning (see below)
println!("{0:0$.v$}", v = val);
println!("{0:v$.0$}", v = val);
println!("{v:0$.0$}", v = val);
println!("{v:v$.0$}", v = val);
println!("{v:0$.v$}", v = val);
println!("{v:v$.v$}", v = val);Expected
I expected to see this happen (one of these):
- suggest corrected version
62 | println!("{v:v$}", v = val);
- ignore it as part of named_arguments_used_positionally, but warn as part of some new warning like
argument_used_multiple_times_as_value_and_as_format_or_precision(the name needs some work :) )
Current behavior
Instead, rustc showed this incorrect suggestion:
warning: named argument `v` is not used by name
--> src/main.rs:64:23
|
64 | println!("{:0$}", v = val);
| ----- ^ this named argument is only referred to by position in formatting string
| |
| this formatting argument uses named argument `v` by position
|
= note: `#[warn(named_arguments_used_positionally)]` on by default
help: use the named argument by name to avoid ambiguity
|
64 | println!("{v}", v = val);
| ~~~
Meta
rustc --version --verbose:
cargo 1.64.0-nightly (d8d30a753 2022-07-19)
release: 1.64.0-nightly
commit-hash: d8d30a75376f78bb0fabe3d28ee9d87aa8035309
commit-date: 2022-07-19
host: x86_64-unknown-linux-gnu
libgit2: 1.4.2 (sys:0.14.2 vendored)
libcurl: 7.83.1-DEV (sys:0.4.55+curl-7.83.1 vendored ssl:OpenSSL/1.1.1n)
os: Linux Mint 20.3 (una) [64-bit]