Auto merge of #115214 - Urgau:rfc-3127-trim-paths, r=compiler-errors

Implement rustc part of RFC 3127 trim-paths

This PR implements (or at least tries to) [RFC 3127 trim-paths](https://github.com/rust-lang/rust/issues/111540), the rustc part. That is `-Zremap-path-scope` with all of it's components/scopes.

`@rustbot` label: +F-trim-paths

src/doc/unstable-book/src/compiler-flags/remap-path-scope.md

@@ -0,0 +1,24 @@
+# `remap-path-scope`
+
+The tracking issue for this feature is: [#111540](https://github.com/rust-lang/rust/issues/111540).
+
+------------------------
+
+When the `--remap-path-prefix` option is passed to rustc, source path prefixes in all output will be affected by default.
+The `--remap-path-scope` argument can be used in conjunction with `--remap-path-prefix` to determine paths in which output context should be affected.
+This flag accepts a comma-separated list of values and may be specified multiple times, in which case the scopes are aggregated together. The valid scopes are:
+
+- `macro` - apply remappings to the expansion of `std::file!()` macro. This is where paths in embedded panic messages come from
+- `diagnostics` - apply remappings to printed compiler diagnostics
+- `unsplit-debuginfo` - apply remappings to debug information only when they are written to compiled executables or libraries, but not when they are in split debuginfo files
+- `split-debuginfo` - apply remappings to debug information only when they are written to split debug information files, but not in compiled executables or libraries
+- `split-debuginfo-path` - apply remappings to the paths pointing to split debug information files. Does nothing when these files are not generated.
+- `object` - an alias for `macro,unsplit-debuginfo,split-debuginfo-path`. This ensures all paths in compiled executables or libraries are remapped, but not elsewhere.
+- `all` and `true` - an alias for all of the above, also equivalent to supplying only `--remap-path-prefix` without `--remap-path-scope`.
+
+## Example
+```sh
+# This would produce an absolute path to main.rs in build outputs of
+# "./main.rs".
+rustc --remap-path-prefix=$(PWD)=/remapped -Zremap-path-prefix=object main.rs
+```

src/librustdoc/html/sources.rs

@@ -225,7 +225,8 @@ impl SourceCollector<'_, '_> {
         cur.push(&fname);
 
         let title = format!("{} - source", src_fname.to_string_lossy());
-        let desc = format!("Source of the Rust file `{}`.", filename.prefer_remapped());
+        let desc =
+            format!("Source of the Rust file `{}`.", filename.prefer_remapped_unconditionaly());
         let page = layout::Page {
             title: &title,
             css_class: "src",

src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs

@@ -494,7 +494,7 @@ impl SerializableSpan {
         let loc: Loc = cx.sess().source_map().lookup_char_pos(span.lo());
 
         Self {
-            path: format!("{}", loc.file.name.prefer_remapped()),
+            path: format!("{}", loc.file.name.prefer_remapped_unconditionaly()),
             line: loc.line,
         }
     }

src/tools/miri/src/shims/backtrace.rs

@@ -135,7 +135,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             this.tcx.sess.source_map().lookup_char_pos(BytePos(offset.bytes().try_into().unwrap()));
 
         let name = fn_instance.to_string();
-        let filename = lo.file.name.prefer_remapped().to_string();
+        let filename = lo.file.name.prefer_remapped_unconditionaly().to_string();
 
         Ok((fn_instance, lo, name, filename))
     }