add "library" to RUSTC_IF_UNCHANGED_ALLOWED_PATHS

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

Author: onur-ozkan

src/bootstrap/src/core/builder/tests.rs

@@ -259,16 +259,10 @@ fn ci_rustc_if_unchanged_logic() {
     builder.run_step_descriptions(&Builder::get_step_descriptions(config.cmd.kind()), &[]);
 
     // Make sure "if-unchanged" logic doesn't try to use CI rustc while there are changes
-    // in compiler and/or library.
+    // in "compiler" tree.
     if config.download_rustc_commit.is_some() {
-        let mut paths = vec!["compiler"];
-
-        // Handle library tree the same way as in `Config::download_ci_rustc_commit`.
-        if builder.config.is_running_on_ci {
-            paths.push("library");
-        }
-
-        let has_changes = config.last_modified_commit(&paths, "download-rustc", true).is_none();
+        let has_changes =
+            config.last_modified_commit(&["compiler"], "download-rustc", true).is_none();
 
         assert!(
             !has_changes,

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

@@ -44,6 +44,7 @@ use crate::utils::helpers::{self, exe, output, t};
 /// final output/compiler, which can be significantly affected by changes made to the bootstrap sources.
 #[rustfmt::skip] // We don't want rustfmt to oneline this list
 pub(crate) const RUSTC_IF_UNCHANGED_ALLOWED_PATHS: &[&str] = &[
+    ":!library",
     ":!src/tools",
     ":!src/librustdoc",
     ":!src/rustdoc-json-types",
@@ -3057,24 +3058,14 @@ impl Config {
             }
         };
 
-        // RUSTC_IF_UNCHANGED_ALLOWED_PATHS
-        let mut allowed_paths = RUSTC_IF_UNCHANGED_ALLOWED_PATHS.to_vec();
-
-        // In CI, disable ci-rustc if there are changes in the library tree. But for non-CI, allow
-        // these changes to speed up the build process for library developers. This provides consistent
-        // functionality for library developers between `download-rustc=true` and `download-rustc="if-unchanged"`
-        // options.
-        //
-        // If you update "library" logic here, update `builder::tests::ci_rustc_if_unchanged_logic` test
-        // logic accordingly.
-        if !self.is_running_on_ci {
-            allowed_paths.push(":!library");
-        }
-
         let commit = if self.rust_info.is_managed_git_subrepository() {
             // Look for a version to compare to based on the current commit.
             // Only commits merged by bors will have CI artifacts.
-            match self.last_modified_commit(&allowed_paths, "download-rustc", if_unchanged) {
+            match self.last_modified_commit(
+                RUSTC_IF_UNCHANGED_ALLOWED_PATHS,
+                "download-rustc",
+                if_unchanged,
+            ) {
                 Some(commit) => commit,
                 None => {
                     if if_unchanged {