Auto merge of #150110 - Urgau:remap-relative-library, r=jieyouxu

Prefer remapping the relative `library/` and `compiler/` directories

This is done to avoid leaking the relative paths to the standard library after the overall of filenames in #149709.

Noted that the paths were already leaking before, but to a lesser extent since most (but not all) the paths embedded in the distributed `rlib` were absolute.

In general Cargo compiles workspace members with relative paths, so it's better anyway to remap the relative path.

In addition to our tests I have manually confirmed that it also works as expected for the printed diagnostics paths.

cf. https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/remapping.20of.20the.20standard.20library/near/564093571

Author: bors

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1675,15 +1675,14 @@ impl<'a> CrateMetadataRef<'a> {
                 for virtual_dir in virtual_source_base_dir.iter().flatten() {
                     if let Some(real_dir) = &real_source_base_dir
                         && let rustc_span::FileName::Real(old_name) = name
-                        && let (_working_dir, embeddable_name) =
-                            old_name.embeddable_name(RemapPathScopeComponents::MACRO)
-                        && let Ok(rest) = embeddable_name.strip_prefix(virtual_dir)
+                        && let virtual_path = old_name.path(RemapPathScopeComponents::MACRO)
+                        && let Ok(rest) = virtual_path.strip_prefix(virtual_dir)
                     {
                         let new_path = real_dir.join(rest);
 
                         debug!(
                             "try_to_translate_virtual_to_real: `{}` -> `{}`",
-                            embeddable_name.display(),
+                            virtual_path.display(),
                             new_path.display(),
                         );
 

src/bootstrap/src/core/builder/cargo.rs

@@ -1032,10 +1032,7 @@ impl Builder<'_> {
                     self.build.debuginfo_map_to(GitRepo::Rustc, RemapScheme::Compiler)
                 {
                     // When building compiler sources, we want to apply the compiler remap scheme.
-                    cargo.env(
-                        "RUSTC_DEBUGINFO_MAP",
-                        format!("{}={}", self.build.src.display(), map_to),
-                    );
+                    cargo.env("RUSTC_DEBUGINFO_MAP", format!("compiler/={map_to}/compiler"));
                     cargo.env("CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR", map_to);
                 }
             }
@@ -1047,10 +1044,7 @@ impl Builder<'_> {
                 if let Some(ref map_to) =
                     self.build.debuginfo_map_to(GitRepo::Rustc, RemapScheme::NonCompiler)
                 {
-                    cargo.env(
-                        "RUSTC_DEBUGINFO_MAP",
-                        format!("{}={}", self.build.src.display(), map_to),
-                    );
+                    cargo.env("RUSTC_DEBUGINFO_MAP", format!("library/={map_to}/library"));
                 }
             }
         }