Unnamed repository; edit this file 'description' to name the repository.
Auto merge of #140514 - m-ou-se:proc-macro-span-file, r=Amanieu
Stabilize proc_macro::Span::{file, local_file}.
Stabilizes this part of https://github.com/rust-lang/rust/issues/54725:
```rust
impl Span {
pub fn file(&self) -> String; // Mapped/artificial file name, for display purposes.
pub fn local_file(&self) -> Option<PathBuf>; // Real file name as it exists on the local file system.
}
```
See also the naming discussion in https://github.com/rust-lang/rust/issues/139903
