[estebank]

When missing const param in impl, provide complete suggestion:

error[E0107]: missing generics for struct `a::Foo`
  --> $DIR/impl-block-missing-const-generics.rs:6:10
   |
LL |     impl Foo {}
   |          ^^^ expected 1 generic argument
   |
note: struct defined here, with 1 generic parameter: `AHA`
  --> $DIR/impl-block-missing-const-generics.rs:4:12
   |
LL |     struct Foo<const AHA: usize>{}
   |            ^^^ ----------------
help: add missing generic argument
   |
LL |     impl<const AHA: usize> Foo<AHA> {}
   |         ++++++++++++++++++    +++++

Previously we only suggested Foo<AHA> without the impl<const AHA: usize>.

Fix #91119.

Point at const param declaration when constant is not expected type:

error: the constant `N` is not of type `usize`
  --> $DIR/const-in-impl-fn-return-type.rs:12:32
   |
LL |     fn func<const N: u32>() -> [(); N];
   |             ------------       ^^^^^^^ expected `usize`, found `u32`
   |             |
   |             found this const parameter
   |
   = note: the length of array `[(); N]` must be type `usize`

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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

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