Un-remap rustc-dev component paths

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1759,6 +1759,17 @@ impl<'a> CrateMetadataRef<'a> {
                     &mut name,
                 );
 
+                // If this file is under $sysroot/lib/rustlib/rustc-src/
+                // and the user wish to simulate remapping with -Z simulate-remapped-rust-src-base,
+                // then we change `name` to a similar state as if the rust was bootstrapped
+                // with `remap-debuginfo = true`.
+                try_to_translate_real_to_virtual(
+                    option_env!("CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR"),
+                    &sess.opts.real_rustc_dev_source_base_dir,
+                    "compiler",
+                    &mut name,
+                );
+
                 // If this file's path has been remapped to `/rustc/$hash`,
                 // we might be able to reverse that.
                 //
@@ -1770,6 +1781,17 @@ impl<'a> CrateMetadataRef<'a> {
                     &mut name,
                 );
 
+                // If this file's path has been remapped to `/rustc-dev/$hash`,
+                // we might be able to reverse that.
+                //
+                // NOTE: if you update this, you might need to also update bootstrap's code for generating
+                // the `rustc-dev` component in `Src::run` in `src/bootstrap/dist.rs`.
+                try_to_translate_virtual_to_real(
+                    option_env!("CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR"),
+                    &sess.opts.real_rustc_dev_source_base_dir,
+                    &mut name,
+                );
+
                 let local_version = sess.source_map().new_imported_source_file(
                     name,
                     src_hash,

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_unused_externs: JsonUnusedExterns::No,
@@ -2713,6 +2714,10 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         // 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(
@@ -2766,6 +2771,7 @@ 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_unused_externs,

compiler/rustc_session/src/options.rs

@@ -397,6 +397,15 @@ top_level_options!(
         /// (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

src/doc/rustc-dev-guide/src/tests/ui.md

@@ -113,6 +113,8 @@ Compiletest makes the following replacements on the compiler output:
 - The base directory where the test's output goes is replaced with
   `$TEST_BUILD_DIR`. This only comes up in a few rare circumstances. Example:
   `/path/to/rust/build/x86_64-unknown-linux-gnu/test/ui`
+- The real directory to the standard library source is replaced with `$SRC_DIR_REAL`.
+- The real directory to the compiler source is replaced with `$COMPILER_DIR_REAL`.
 - Tabs are replaced with `\t`.
 - Backslashes (`\`) are converted to forward slashes (`/`) within paths (using a
   heuristic). This helps normalize differences with Windows-style paths.

src/tools/compiletest/src/runtest.rs

@@ -2371,6 +2371,12 @@ impl<'test> TestCx<'test> {
         let rust_src_dir = rust_src_dir.read_link_utf8().unwrap_or(rust_src_dir.to_path_buf());
         normalize_path(&rust_src_dir.join("library"), "$SRC_DIR_REAL");
 
+        // Real paths into the compiler
+        let rustc_src_dir = &self.config.sysroot_base.join("lib/rustlib/rustc-src/rust");
+        rustc_src_dir.try_exists().expect(&*format!("{} should exists", rustc_src_dir));
+        let rustc_src_dir = rustc_src_dir.read_link_utf8().unwrap_or(rustc_src_dir.to_path_buf());
+        normalize_path(&rustc_src_dir.join("compiler"), "$COMPILER_DIR_REAL");
+
         // eg.
         // /home/user/rust/build/x86_64-unknown-linux-gnu/test/ui/<test_dir>/$name.$revision.$mode/
         normalize_path(&self.output_base_dir(), "$TEST_BUILD_DIR");

tests/ui-fulldeps/rustc-dev-remap.only-remap.stderr

@@ -0,0 +1,15 @@
+error[E0277]: the trait bound `NotAValidResultType: VisitorResult` is not satisfied
+  --> $DIR/rustc-dev-remap.rs:LL:COL
+   |
+LL |     type Result = NotAValidResultType;
+   |                   ^^^^^^^^^^^^^^^^^^^ the trait `VisitorResult` is not implemented for `NotAValidResultType`
+   |
+   = help: the following other types implement trait `VisitorResult`:
+             ()
+             ControlFlow<T>
+note: required by a bound in `rustc_ast::visit::Visitor::Result`
+  --> /rustc-dev/xyz/compiler/rustc_ast/src/visit.rs:LL:COL
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui-fulldeps/rustc-dev-remap.remap-unremap.stderr

@@ -0,0 +1,18 @@
+error[E0277]: the trait bound `NotAValidResultType: VisitorResult` is not satisfied
+  --> $DIR/rustc-dev-remap.rs:LL:COL
+   |
+LL |     type Result = NotAValidResultType;
+   |                   ^^^^^^^^^^^^^^^^^^^ the trait `VisitorResult` is not implemented for `NotAValidResultType`
+   |
+   = help: the following other types implement trait `VisitorResult`:
+             ()
+             ControlFlow<T>
+note: required by a bound in `rustc_ast::visit::Visitor::Result`
+  --> $COMPILER_DIR_REAL/rustc_ast/src/visit.rs:LL:COL
+   |
+LL |     type Result: VisitorResult = ();
+   |                  ^^^^^^^^^^^^^ required by this bound in `Visitor::Result`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui-fulldeps/rustc-dev-remap.rs

@@ -0,0 +1,30 @@
+//@ check-fail
+//
+//@ ignore-stage1
+//@ ignore-cross-compile
+//@ ignore-remote
+//
+//@ revisions: only-remap remap-unremap
+//@ compile-flags: -Z simulate-remapped-rust-src-base=/rustc-dev/xyz
+//@ [remap-unremap]compile-flags: -Ztranslate-remapped-path-to-local-path=yes
+
+// The $SRC_DIR*.rs:LL:COL normalisation doesn't kick in automatically
+// as the remapped revision will begin with $COMPILER_DIR_REAL,
+// so we have to do it ourselves.
+//@ normalize-stderr: ".rs:\d+:\d+" -> ".rs:LL:COL"
+
+#![feature(rustc_private)]
+
+extern crate rustc_ast;
+
+use rustc_ast::visit::Visitor;
+
+struct MyStruct;
+struct NotAValidResultType;
+
+impl Visitor<'_> for MyStruct {
+    type Result = NotAValidResultType;
+    //~^ ERROR the trait bound `NotAValidResultType: VisitorResult` is not satisfied
+}
+
+fn main() {}