use is_variant_list_non_exhaustive/is_field_list_non_exhaustive

remove unused tcx

inline non_exhaustive def/variant check

Fix rust-lang#46969.

…ons_non_exhaustive, r=petrochenkov

Disable missing_copy_implementations lint on non_exhaustive types

Fixes rust-lang#116766

Disable effects in libcore again

r? `@fee1-dead`

This was accidentally allowed by rust-lang#114776 without feature gates

…rrors

Suggest constraining assoc types in more cases

Fix rust-lang#46969.

```
error[E0308]: mismatched types
  --> $DIR/suggest-contraining-assoc-type-because-of-assoc-const.rs:12:21
   |
LL |     const N: C::M = 4u8;
   |                     ^^^ expected associated type, found `u8`
   |
   = note: expected associated type `<C as O>::M`
                         found type `u8`
help: consider constraining the associated type `<C as O>::M` to `u8`
   |
LL | impl<C: O<M = u8>> U<C> for u16 {
   |          ++++++++

```

…, r=fee1-dead

Don't compare host param by name

Seems sketchy to be searching for `sym::host` by name, especially when we can get the actual index with not very much work.

r? fee1-dead

…li-obk

revert rust-lang#114586

Reverts rust-lang#114586.

cc rust-lang#116877 (not closing until this gets a beta backport)
fixes rust-lang#116684
fixes rust-lang#114586 (comment)

r? `@oli-obk` or `@lcnr`