Auto merge of #9233 - nyurik:capture-vars, r=Alexendoo

new uninlined_format_args lint to inline explicit arguments

Implement https://github.com/rust-lang/rust-clippy/issues/8368 - a new lint to inline format arguments such as `print!("{}", var)` into `print!("{var}")`.

### Supported cases

code | suggestion | comment
---|---|---
`print!("{}", var)` | `print!("{var}")` |  simple variables
`print!("{0}", var)` | `print!("{var}")` |  positional variables
`print!("{v}", v=var)` | `print!("{var}")` |  named variables
`print!("{0} {0}", var)` | `print!("{var} {var}")` |  aliased variables
`print!("{0:1$}", var, width)` | `print!("{var:width$}")` |  width support
`print!("{0:.1$}", var, prec)` | `print!("{var:.prec$}")` |  precision support
`print!("{:.*}", prec, var)` | `print!("{var:.prec$}")` |  asterisk support

### Known Problems

* There may be a false positive if the format string is wrapped in a macro call:
```rust
# let var = 42;
macro_rules! no_param_str { () => { "{}" }; }
macro_rules! pass_through { ($expr:expr) => { $expr }; }
println!(no_param_str!(), var);
println!(pass_through!("{}"), var);
```

* Format string uses an indexed argument that cannot be inlined.
Supporting this case requires re-indexing of the format string.
Until implemented, `print!("{0}={1}", var, 1+2)` should be changed to `print!("{var}={0}", 1+2)` by hand.

changelog: [`uninlined_format_args`]: A new lint to inline format arguments, i.e. `print!("{}", var)` into `print!("{var}")`

0 files changed, 0 insertions, 0 deletions