Rollup merge of #142377 - Urgau:unremap-rustc-dev, r=jieyouxu

Try unremapping compiler sources

See [#t-compiler/help > Span pointing to wrong file location (`rustc-dev` component)](https://rust-lang.zulipchat.com/#narrow/channel/182449-t-compiler.2Fhelp/topic/Span.20pointing.20to.20wrong.20file.20location.20.28.60rustc-dev.60.20component.29/with/521087083).

This PR is a follow-up to rust-lang/rust#141751 regarding the compiler side.

Specifically we now take into account the `CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR` env from rust-lang/rust#141751 when trying to unremap sources from `$sysroot/lib/rustlib/rustc-src/rust` (the `rustc-dev` component install directory).

Best reviewed commit by commit.

cc ``@samueltardieu``
r? ``@jieyouxu``

2 files changed, 26 insertions, 7 deletions

diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 19db01585e3..87e4b0a17aa 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -1364,6 +1364,7 @@ impl Default for Options {
             cli_forced_local_thinlto_off: false,
             remap_path_prefix: Vec::new(),
             real_rust_source_base_dir: None,
+            real_rustc_dev_source_base_dir: None,
             edition: DEFAULT_EDITION,
             json_artifact_notifications: false,
             json_timings: false,
@@ -2713,9 +2714,8 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
 
     let sysroot = filesearch::materialize_sysroot(sysroot_opt);
 
-    let real_rust_source_base_dir = {
-        // This is the location used by the `rust-src` `rustup` component.
-        let mut candidate = sysroot.join("lib/rustlib/src/rust");
+    let real_source_base_dir = |suffix: &str, confirm: &str| {
+        let mut candidate = sysroot.join(suffix);
         if let Ok(metadata) = candidate.symlink_metadata() {
             // Replace the symlink bootstrap creates, with its destination.
             // We could try to use `fs::canonicalize` instead, but that might
@@ -2728,9 +2728,17 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         }
 
         // Only use this directory if it has a file we can expect to always find.
-        candidate.join("library/std/src/lib.rs").is_file().then_some(candidate)
+        candidate.join(confirm).is_file().then_some(candidate)
     };
 
+    let real_rust_source_base_dir =
+        // This is the location used by the `rust-src` `rustup` component.
+        real_source_base_dir("lib/rustlib/src/rust", "library/std/src/lib.rs");
+
+    let real_rustc_dev_source_base_dir =
+        // This is the location used by the `rustc-dev` `rustup` component.
+        real_source_base_dir("lib/rustlib/rustc-src/rust", "compiler/rustc/src/main.rs");
+
     let mut search_paths = vec![];
     for s in &matches.opt_strs("L") {
         search_paths.push(SearchPath::from_cli_opt(
@@ -2784,6 +2792,7 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         cli_forced_local_thinlto_off: disable_local_thinlto,
         remap_path_prefix,
         real_rust_source_base_dir,
+        real_rustc_dev_source_base_dir,
         edition,
         json_artifact_notifications,
         json_timings,
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index d22f9de6525..31b4237d3b2 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -395,15 +395,25 @@ top_level_options!(
 
         /// Remap source path prefixes in all output (messages, object files, debug, etc.).
         remap_path_prefix: Vec<(PathBuf, PathBuf)> [TRACKED_NO_CRATE_HASH],
-        /// Base directory containing the `src/` for the Rust standard library, and
-        /// potentially `rustc` as well, if we can find it. Right now it's always
-        /// `$sysroot/lib/rustlib/src/rust` (i.e. the `rustup` `rust-src` component).
+
+        /// Base directory containing the `library/` directory for the Rust standard library.
+        /// Right now it's always `$sysroot/lib/rustlib/src/rust`
+        /// (i.e. the `rustup` `rust-src` component).
         ///
         /// This directory is what the virtual `/rustc/$hash` is translated back to,
         /// if Rust was built with path remapping to `/rustc/$hash` enabled
         /// (the `rust.remap-debuginfo` option in `bootstrap.toml`).
         real_rust_source_base_dir: Option<PathBuf> [TRACKED_NO_CRATE_HASH],
 
+        /// Base directory containing the `compiler/` directory for the rustc sources.
+        /// Right now it's always `$sysroot/lib/rustlib/rustc-src/rust`
+        /// (i.e. the `rustup` `rustc-dev` component).
+        ///
+        /// This directory is what the virtual `/rustc-dev/$hash` is translated back to,
+        /// if Rust was built with path remapping to `/rustc/$hash` enabled
+        /// (the `rust.remap-debuginfo` option in `bootstrap.toml`).
+        real_rustc_dev_source_base_dir: Option<PathBuf> [TRACKED_NO_CRATE_HASH],
+
         edition: Edition [TRACKED],
 
         /// `true` if we're emitting JSON blobs about each artifact produced