From b314c73d48c45b5aaf47d1c7eac6f36a2fda81cf Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Fri, 20 Feb 2026 15:13:18 +0000
Subject: [PATCH] Remove rustc-dev un-remapping

During local development it doesn't matter, for end users it doesn't
help as it doesn't affect the precompiled rustc executable and during
development of custom drivers, most paths are kept remapped anyway due
to rustc not getting recompiled. As such for the use cases where you
want the original source paths, you either already have the original
source paths or un-remapping doesn't have any effect.
---
 compiler/rustc_metadata/src/rmeta/decoder.rs | 22 --------------------
 src/bootstrap/src/core/builder/cargo.rs      |  6 +-----
 2 files changed, 1 insertion(+), 27 deletions(-)

diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
index bd5b3893e4e8a..91733d129f7e7 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -1772,17 +1772,6 @@ impl<'a> CrateMetadataRef<'a> {
                     &mut name,
                 );
 
-                // If this file is under $sysroot/lib/rustlib/rustc-src/
-                // and the user wish to simulate remapping with -Z simulate-remapped-rust-src-base,
-                // then we change `name` to a similar state as if the rust was bootstrapped
-                // with `remap-debuginfo = true`.
-                try_to_translate_real_to_virtual(
-                    option_env!("CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR"),
-                    &tcx.sess.opts.real_rustc_dev_source_base_dir,
-                    "compiler",
-                    &mut name,
-                );
-
                 // If this file's path has been remapped to `/rustc/$hash`,
                 // we might be able to reverse that.
                 //
@@ -1794,17 +1783,6 @@ 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"),
-                    &tcx.sess.opts.real_rustc_dev_source_base_dir,
-                    &mut name,
-                );
-
                 let local_version = tcx.sess.source_map().new_imported_source_file(
                     name,
                     src_hash,
diff --git a/src/bootstrap/src/core/builder/cargo.rs b/src/bootstrap/src/core/builder/cargo.rs
index 2673b6c1c7fb6..50e563081e1be 100644
--- a/src/bootstrap/src/core/builder/cargo.rs
+++ b/src/bootstrap/src/core/builder/cargo.rs
@@ -1029,10 +1029,9 @@ impl Builder<'_> {
         }
 
         // `rustc` needs to know the remapping scheme, in order to know how to reverse it (unremap)
-        // later. Two env vars are set and made available to the compiler
+        // later. The following env var is set and made available to the compiler:
         //
         // - `CFG_VIRTUAL_RUST_SOURCE_BASE_DIR`: `rust-src` remap scheme (`NonCompiler`)
-        // - `CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR`: `rustc-dev` remap scheme (`Compiler`)
         //
         // Keep this scheme in sync with `rustc_metadata::rmeta::decoder`'s
         // `try_to_translate_virtual_to_real`.
@@ -1051,9 +1050,6 @@ impl Builder<'_> {
                 if let Some(ref map_to) =
                     self.build.debuginfo_map_to(GitRepo::Rustc, RemapScheme::Compiler)
                 {
-                    // Tell the compiler which prefix was used for remapping the compiler it-self
-                    cargo.env("CFG_VIRTUAL_RUSTC_DEV_SOURCE_BASE_DIR", map_to);
-
                     // When building compiler sources, we want to apply the compiler remap scheme.
                     let map = [
                         // Cargo use relative paths for workspace members, so let's remap those.