Rollup merge of #118234 - tgross35:type_name_of_value, r=dtolnay

Stabilize `type_name_of_val`

Make the following API stable:

```rust
// in core::any
pub fn type_name_of_val<T: ?Sized>(_val: &T) -> &'static str
```

This is a convenience method to get the type name of a value, as opposed to `type_name` that takes a type as a generic.

Const stability is not added because this relies on `type_name` which is also not const. That has a blocking issue https://github.com/rust-lang/rust/issues/97156.

Wording was also changed to direct most of the details to `type_name` so we don't have as much duplicated documentation.

Fixes tracking issue #66359.

There were two main concerns in the tracking issue:

1. Naming: `type_name_of` and `type_name_of_val` seem like the only mentioned options. Differences in opinion here come from `std::mem::{size_of, align_of, size_of_val, align_of_val}`. This PR leaves the name as `type_name_of_val`, but I can change if desired since it is pretty verbose.
2. What this displays for `&dyn`: I don't think that having `type_name_of_val` function resolve those is worth the headache it would be, see https://github.com/rust-lang/rust/issues/66359#issuecomment-1718480774 for some workarounds. I also amended the docs wording to leave it open-ended, in case we have means to change that behavior in the future.

``@rustbot`` label -T-libs +T-libs-api +needs-fcp
r? libs-api

0 files changed, 0 insertions, 0 deletions