…-errors

`maybe_lint_impl_trait`: separate `is_downgradable` from `is_object_safe`

rust-lang#119752 leveraged and overloaded `is_object_safe` to prevent an ICE, but accurate object safety information is needed for precise suggestions. This separates out `is_downgradable`, used for the ICE prevention, and `is_object_safe`, which returns to its original meaning.

…-errors

`maybe_lint_impl_trait`: separate `is_downgradable` from `is_object_safe`

rust-lang#119752 leveraged and overloaded `is_object_safe` to prevent an ICE, but accurate object safety information is needed for precise suggestions. This separates out `is_downgradable`, used for the ICE prevention, and `is_object_safe`, which returns to its original meaning.

…iaskrgr

Rollup of 11 pull requests

Successful merges:

 - rust-lang#117910 (Refactor uses of `objc_msgSend` to no longer have clashing definitions)
 - rust-lang#118639 (Undeprecate lint `unstable_features` and make use of it in the compiler)
 - rust-lang#119801 (Fix deallocation with wrong allocator in (A)Rc::from_box_in)
 - rust-lang#120058 (bootstrap: improvements for compiler builds)
 - rust-lang#120059 (Make generic const type mismatches not hide trait impls from the trait solver)
 - rust-lang#120097 (Report unreachable subpatterns consistently)
 - rust-lang#120137 (Validate AggregateKind types in MIR)
 - rust-lang#120164 (`maybe_lint_impl_trait`: separate `is_downgradable` from `is_object_safe`)
 - rust-lang#120181 (Allow any `const` expression blocks in `thread_local!`)
 - rust-lang#120204 (Builtin macros effectively have implicit #[collapse_debuginfo(yes)])
 - rust-lang#120218 (rustfmt: Check that a token can begin a nonterminal kind before parsing it as a macro arg)

r? `@ghost`
`@rustbot` modify labels: rollup

…iaskrgr

Rollup of 10 pull requests

Successful merges:

 - rust-lang#117910 (Refactor uses of `objc_msgSend` to no longer have clashing definitions)
 - rust-lang#118639 (Undeprecate lint `unstable_features` and make use of it in the compiler)
 - rust-lang#119801 (Fix deallocation with wrong allocator in (A)Rc::from_box_in)
 - rust-lang#120058 (bootstrap: improvements for compiler builds)
 - rust-lang#120059 (Make generic const type mismatches not hide trait impls from the trait solver)
 - rust-lang#120097 (Report unreachable subpatterns consistently)
 - rust-lang#120137 (Validate AggregateKind types in MIR)
 - rust-lang#120164 (`maybe_lint_impl_trait`: separate `is_downgradable` from `is_object_safe`)
 - rust-lang#120181 (Allow any `const` expression blocks in `thread_local!`)
 - rust-lang#120218 (rustfmt: Check that a token can begin a nonterminal kind before parsing it as a macro arg)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup merge of rust-lang#120164 - trevyn:is_downgradable, r=compiler-errors

`maybe_lint_impl_trait`: separate `is_downgradable` from `is_object_safe`

rust-lang#119752 leveraged and overloaded `is_object_safe` to prevent an ICE, but accurate object safety information is needed for precise suggestions. This separates out `is_downgradable`, used for the ICE prevention, and `is_object_safe`, which returns to its original meaning.