move rust.description to build.description

Signed-off-by: onur-ozkan <work@onurozkan.dev>

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
@@ -614,17 +625,6 @@
 # otherwise, it's "dev".
 #channel = if "is a tarball source" { content of `src/ci/channel` file } 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/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,
@@ -1827,7 +1830,7 @@ impl Config {
                 randomize_layout,
                 default_linker,
                 channel: _, // already handled above
-                description,
+                description: rust_description,
                 musl_root,
                 rpath,
                 verbose_tests,
@@ -1920,7 +1923,12 @@ 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
@@ -1986,6 +1994,7 @@ 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,