error[E0308]: mismatched types
  --> $DIR/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs:19:9
   |
LL |     let P() = U {};
   |         ^^^   ---- this expression has type `U`
   |         |
   |         expected struct `U`, found struct `P`
   |
   = note: expected struct `U`
              found struct `P<_>`

error[E0023]: this pattern has 0 fields, but the corresponding tuple struct has 1 field
  --> $DIR/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs:19:9
   |
LL | struct P<T>(T); // 1 type parameter wanted
   | --------------- tuple struct defined here
...
LL |     let P() = U {};
   |         ^^^ expected 1 field, found 0
   |
help: use `_` to explicitly ignore each field
   |
LL |     let P(_) = U {};
   |           ^
help: use `..` to ignore all fields
   |
LL |     let P(..) = U {};
   |           ^^

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0023, E0308.
For more information about an error, try `rustc --explain E0023`.