Auto merge of #8857 - smoelius:fix-8855, r=flip1995

Add test for #8855

Fix #8855

Here is what I think is going on.

First, the expression `format!("{:>6} {:>6}", a, b.to_string())` expands to:
```rust
{
    let res =
        ::alloc::fmt::format(::core::fmt::Arguments::new_v1_formatted(&["",
                            " "],
                &[::core::fmt::ArgumentV1::new_display(&a),
                            ::core::fmt::ArgumentV1::new_display(&b.to_string())],
                &[::core::fmt::rt::v1::Argument {
                                position: 0usize,
                                format: ::core::fmt::rt::v1::FormatSpec {
                                    fill: ' ',
                                    align: ::core::fmt::rt::v1::Alignment::Right,
                                    flags: 0u32,
                                    precision: ::core::fmt::rt::v1::Count::Implied,
                                    width: ::core::fmt::rt::v1::Count::Is(6usize),
                                },
                            },
                            ::core::fmt::rt::v1::Argument {
                                position: 1usize,
                                format: ::core::fmt::rt::v1::FormatSpec {
                                    fill: ' ',
                                    align: ::core::fmt::rt::v1::Alignment::Right,
                                    flags: 0u32,
                                    precision: ::core::fmt::rt::v1::Count::Implied,
                                    width: ::core::fmt::rt::v1::Count::Is(6usize),
                                },
                            }], unsafe { ::core::fmt::UnsafeArg::new() }));
    res
}
```
When I dump the expressions that get past the call to `has_string_formatting` [here](https://github.com/rust-lang/rust-clippy/blob/b312ad7d0cf0f30be2bd4658b71a3520a2e76709/clippy_lints/src/format_args.rs#L83), I see more than I would expect.

In particular, I see this subexpression of the above:
```
                &[::core::fmt::ArgumentV1::new_display(&a),
                            ::core::fmt::ArgumentV1::new_display(&b.to_string())],
```

This suggests to me that more expressions are getting past [this call](https://github.com/rust-lang/rust-clippy/blob/b312ad7d0cf0f30be2bd4658b71a3520a2e76709/clippy_lints/src/format_args.rs#L71) to `FormatArgsExpn::parse` than should.

Those expressions are then visited, but no `::core::fmt::rt::v1::Argument`s are found and pushed [here](https://github.com/rust-lang/rust-clippy/blob/b312ad7d0cf0f30be2bd4658b71a3520a2e76709/clippy_utils/src/macros.rs#L407).

As a result, the expressions appear unformatted, hence, the false positive.

My proposed fix is to restrict `FormatArgsExpn::parse` so that it only matches `Call` expressions.

cc: `@akanalytics`

changelog: none

0 files changed, 0 insertions, 0 deletions