Stabilize proc_macro::Span::{file, local_file}.

[m-ou-se]

Stabilizes this part of #54725:

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 #139903

[m-ou-se]

@rfcbot merge

[rfcbot]

Team member @m-ou-se has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Amanieu
• @BurntSushi
• @dtolnay
• @joshtriplett
• @m-ou-se

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[m-ou-se]

I think we should ship (stable) file and local_file in the same rust version as line and column. So it would be good if we can merge this into 1.88 too. :)

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔

[sam0x17]

very excited to see this coming to stable, have been waiting for this for years ❤️