Reparse all suggestions to prevent suggesting syntactically invalid code

I frequently see Clippy make attempted suggestions involving macro calls, such as the following:

// [dependencies]
// derivative = "=1.0.4"

use derivative::Derivative;

#[derive(Derivative)]
#[derivative(Debug)]
struct S { x: () }

warning: this match could be written as a `let` statement
 --> src/main.rs:7:1
  |
7 | #[derivative(Debug)]
  | ^
  |
  = note: `#[warn(clippy::match_single_binding)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#match_single_binding
help: consider using `let` statement
  |
7 | let Derivative = #;
8 | Derivative[derivative(Debug)]
  |

Often it's possible to fix these by tweaking some spans in the macro implementation or by putting codepaths into Clippy to block certain lints in macro-generated code. However, I wonder whether it would be better to fix this category of broken suggestions by passing all suggested code through a parser prior to emitting a suggestion. In the above, it should be very clear that Clippy's suggested replacement code does not parse, irrespective of what's going on with spans.

use derivative::Derivative;

#[derive(Derivative)]
let Derivative = #;
Derivative[derivative(Debug)]
struct S { x: () }

Since the above suggested code does not parse, Clippy should emit the lint without a suggestion instead.

Meta

• cargo clippy -V: clippy 0.1.52 (107896c 2021-03-15)

Start with the issue's cargo clippy example and examine how Clippy currently emits suggestions for macro calls. Investigate where suggested replacement code could be passed through a parser before emission. Done means syntactically invalid suggestions are suppressed while the lint itself remains available.