…er-errors

add back test for stable-const-can-only-call-stable-const

This got accidentally removed in rust-lang#128596 (file `tests/ui/internal/internal-unstable-const.rs`). The test has little to do with "allow internal unstable" though, so add it in a file that already tests various const stability things.

Also tweak the help that suggests to add `rustc_allow_const_fn_unstable` to make it clear that this needs team approval, since it is a fairly big gun.

…iaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#129207 (Lint that warns when an elided lifetime ends up being a named lifetime)
 - rust-lang#129288 (Use subtyping for `UnsafeFnPointer` coercion, too)
 - rust-lang#129405 (Fixing span manipulation and indentation of the suggestion introduced by rust-lang#126187)
 - rust-lang#129518 (gitignore: ignore ICE reports regardless of directory)
 - rust-lang#129519 (Remove redundant flags from `lower_ty_common` that can be inferred from the HIR)
 - rust-lang#129544 (Removes dead code from the compiler)
 - rust-lang#129553 (add back test for stable-const-can-only-call-stable-const)
 - rust-lang#129590 (Avoid taking reference of &TyKind)

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

Rollup merge of rust-lang#129553 - RalfJung:const-stability, r=compiler-errors

add back test for stable-const-can-only-call-stable-const

This got accidentally removed in rust-lang#128596 (file `tests/ui/internal/internal-unstable-const.rs`). The test has little to do with "allow internal unstable" though, so add it in a file that already tests various const stability things.

Also tweak the help that suggests to add `rustc_allow_const_fn_unstable` to make it clear that this needs team approval, since it is a fairly big gun.