`impl 'a Trait` in argument position emits multible wrong diagnostics

[lukas-code]

I tried this almost-correct code: Playground

fn foo<'a>(_: impl 'a Sized) {}

The current output is:

   Compiling playground v0.0.1 (/playground)
error: expected one of `:`, `@`, or `|`, found `)`
 --> src/lib.rs:1:28
  |
1 | fn foo<'a>(_: impl 'a Sized) {}
  |                            ^ expected one of `:`, `@`, or `|`
  |
  = note: anonymous parameters are removed in the 2018 edition (see RFC 1685)
help: if this is a parameter name, give it a type
  |
1 | fn foo<'a>(_: impl 'a Sized: TypeName) {}
  |                            ++++++++++
help: if this is a type, explicitly ignore the parameter name
  |
1 | fn foo<'a>(_: impl 'a _: Sized) {}
  |                       ++

error: expected one of `)`, `+`, or `,`, found `Sized`
 --> src/lib.rs:1:23
  |
1 | fn foo<'a>(_: impl 'a Sized) {}
  |                      -^^^^^ expected one of `)`, `+`, or `,`
  |                      |
  |                      help: missing `,`

error: at least one trait must be specified
 --> src/lib.rs:1:15
  |
1 | fn foo<'a>(_: impl 'a Sized) {}
  |               ^^^^^^^

error: could not compile `playground` due to 3 previous errors

Ideally the output should look like:

   Compiling playground v0.0.1 (/playground)
error: expected `+` between lifetime and trait
 --> src/lib.rs:1:22
  |
1 | fn foo<'a>(_: impl 'a + Sized) {}
  |                       ^
  |                       |
  |                       help: missing `+`
  |
error: could not compile `playground` due to 1 previous errors

[lyming2007]

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