Make rust.description more general-purpose and pass CFG_VER_DESCRIPTION

config.example.toml

@@ -189,6 +189,17 @@
 # The default stage to use for the `bench` subcommand
 #bench-stage = 2
 
+# A descriptive string to be appended to version output (e.g., `rustc --version`),
+# which is also used in places like debuginfo `DW_AT_producer`. This may be useful for
+# supplementary build information, like distro-specific package versions.
+#
+# The Rust compiler will differentiate between versions of itself, including
+# based on this string, which means that if you wish to be compatible with
+# upstream Rust you need to set this to "". However, note that if you set this to "" but
+# are not actually compatible -- for example if you've backported patches that change
+# behavior -- this may lead to miscompilations or other bugs.
+#description = ""
+
 # Build triple for the pre-compiled snapshot compiler. If `rustc` is set, this must match its host
 # triple (see `rustc --version --verbose`; cross-compiling the rust build system itself is NOT
 # supported). If `rustc` is unset, this must be a platform with pre-compiled host tools
@@ -615,17 +626,6 @@
 # If using tarball sources, default value is "auto-detect", otherwise, it's "dev".
 #channel = if "is a tarball source" { "auto-detect" } else { "dev" }
 
-# A descriptive string to be appended to `rustc --version` output, which is
-# also used in places like debuginfo `DW_AT_producer`. This may be useful for
-# supplementary build information, like distro-specific package versions.
-#
-# The Rust compiler will differentiate between versions of itself, including
-# based on this string, which means that if you wish to be compatible with
-# upstream Rust you need to set this to "". However, note that if you are not
-# actually compatible -- for example if you've backported patches that change
-# behavior -- this may lead to miscompilations or other bugs.
-#description = ""
-
 # The root location of the musl installation directory. The library directory
 # will also need to contain libunwind.a for an unwinding implementation. Note
 # that this option only makes sense for musl targets that produce statically

src/bootstrap/configure.py

@@ -292,7 +292,7 @@ def v(*args):
 v("release-channel", "rust.channel", "the name of the release channel to build")
 v(
     "release-description",
-    "rust.description",
+    "build.description",
     "optional descriptive string for version output",
 )
 v("dist-compression-formats", None, "List of compression formats to use")

src/bootstrap/src/core/build_steps/tool.rs

@@ -234,23 +234,32 @@ pub fn prepare_tool_cargo(
     cargo.env("CFG_VERSION", builder.rust_version());
     cargo.env("CFG_RELEASE_NUM", &builder.version);
     cargo.env("DOC_RUST_LANG_ORG_CHANNEL", builder.doc_rust_lang_org_channel());
+
     if let Some(ref ver_date) = builder.rust_info().commit_date() {
         cargo.env("CFG_VER_DATE", ver_date);
     }
+
     if let Some(ref ver_hash) = builder.rust_info().sha() {
         cargo.env("CFG_VER_HASH", ver_hash);
     }
 
+    if let Some(description) = &builder.config.description {
+        cargo.env("CFG_VER_DESCRIPTION", description);
+    }
+
     let info = GitInfo::new(builder.config.omit_git_hash, &dir);
     if let Some(sha) = info.sha() {
         cargo.env("CFG_COMMIT_HASH", sha);
     }
+
     if let Some(sha_short) = info.sha_short() {
         cargo.env("CFG_SHORT_COMMIT_HASH", sha_short);
     }
+
     if let Some(date) = info.commit_date() {
         cargo.env("CFG_COMMIT_DATE", date);
     }
+
     if !features.is_empty() {
         cargo.arg("--features").arg(features.join(", "));
     }

src/bootstrap/src/core/config/config.rs

@@ -894,6 +894,7 @@ define_config! {
     #[derive(Default)]
     struct Build {
         build: Option<String> = "build",
+        description: Option<String> = "description",
         host: Option<Vec<String>> = "host",
         target: Option<Vec<String>> = "target",
         build_dir: Option<String> = "build-dir",
@@ -1176,6 +1177,7 @@ define_config! {
         incremental: Option<bool> = "incremental",
         default_linker: Option<String> = "default-linker",
         channel: Option<String> = "channel",
+        // FIXME: Remove this field at Q2 2025, it has been replaced by build.description
         description: Option<String> = "description",
         musl_root: Option<String> = "musl-root",
         rpath: Option<bool> = "rpath",
@@ -1583,6 +1585,7 @@ impl Config {
         config.change_id = toml.change_id.inner;
 
         let Build {
+            mut description,
             build,
             host,
             target,
@@ -1831,7 +1834,7 @@ impl Config {
                 randomize_layout,
                 default_linker,
                 channel: _, // already handled above
-                description,
+                description: rust_description,
                 musl_root,
                 rpath,
                 verbose_tests,
@@ -1924,7 +1927,12 @@ impl Config {
             set(&mut config.jemalloc, jemalloc);
             set(&mut config.test_compare_mode, test_compare_mode);
             set(&mut config.backtrace, backtrace);
-            config.description = description;
+            if rust_description.is_some() {
+                eprintln!(
+                    "Warning: rust.description is deprecated. Use build.description instead."
+                );
+            }
+            description = description.or(rust_description);
             set(&mut config.rust_dist_src, dist_src);
             set(&mut config.verbose_tests, verbose_tests);
             // in the case "false" is set explicitly, do not overwrite the command line args
@@ -1990,6 +1998,7 @@ impl Config {
         }
 
         config.reproducible_artifacts = flags.reproducible_artifact;
+        config.description = description;
 
         // We need to override `rust.channel` if it's manually specified when using the CI rustc.
         // This is because if the compiler uses a different channel than the one specified in config.toml,

src/bootstrap/src/utils/change_tracker.rs

@@ -365,4 +365,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "`rust.channel` now supports \"auto-detect\" to load the channel from `src/ci/channel`",
     },
+    ChangeInfo {
+        change_id: 137723,
+        severity: ChangeSeverity::Info,
+        summary: "The rust.description option has moved to build.description and rust.description is now deprecated.",
+    },
 ];