Synchronize LLVM invalidation paths between config and LLVM step

Author: Kobzol

src/bootstrap/src/core/build_steps/llvm.rs

@@ -174,15 +174,18 @@ pub fn prebuilt_llvm_config(
     LlvmBuildStatus::ShouldBuild(Meta { stamp, res, out_dir, root: root.into() })
 }
 
+/// Paths whose changes invalidate LLVM downloads.
+pub const LLVM_INVALIDATION_PATHS: &[&str] = &[
+    "src/llvm-project",
+    "src/bootstrap/download-ci-llvm-stamp",
+    // the LLVM shared object file is named `LLVM-<LLVM-version>-rust-{version}-nightly`
+    "src/version",
+];
+
 /// Detect whether LLVM sources have been modified locally or not.
 pub(crate) fn detect_llvm_freshness(config: &Config, is_git: bool) -> PathFreshness {
     if is_git {
-        config.check_path_modifications(&[
-            "src/llvm-project",
-            "src/bootstrap/download-ci-llvm-stamp",
-            // the LLVM shared object file is named `LLVM-12-rust-{version}-nightly`
-            "src/version",
-        ])
+        config.check_path_modifications(LLVM_INVALIDATION_PATHS)
     } else if let Some(info) = crate::utils::channel::read_commit_info_file(&config.src) {
         PathFreshness::LastModifiedUpstream { upstream: info.sha.trim().to_owned() }
     } else {

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

@@ -23,6 +23,7 @@ use tracing::{instrument, span};
 
 use crate::core::build_steps::compile::CODEGEN_BACKEND_PREFIX;
 use crate::core::build_steps::llvm;
+use crate::core::build_steps::llvm::LLVM_INVALIDATION_PATHS;
 pub use crate::core::config::flags::Subcommand;
 use crate::core::config::flags::{Color, Flags, Warnings};
 use crate::core::download::is_download_ci_available;
@@ -3105,7 +3106,7 @@ impl Config {
             self.update_submodule("src/llvm-project");
 
             // Check for untracked changes in `src/llvm-project`.
-            let has_changes = self.has_changes_from_upstream(&["src/llvm-project"]);
+            let has_changes = self.has_changes_from_upstream(LLVM_INVALIDATION_PATHS);
 
             // Return false if there are untracked changes, otherwise check if CI LLVM is available.
             if has_changes { false } else { llvm::is_ci_llvm_available(self, asserts) }

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

@@ -11,6 +11,7 @@ use super::flags::Flags;
 use super::{ChangeIdWrapper, Config, RUSTC_IF_UNCHANGED_ALLOWED_PATHS};
 use crate::core::build_steps::clippy::{LintConfig, get_clippy_rules_in_order};
 use crate::core::build_steps::llvm;
+use crate::core::build_steps::llvm::LLVM_INVALIDATION_PATHS;
 use crate::core::config::{LldMode, Target, TargetSelection, TomlConfig};
 
 pub(crate) fn parse(config: &str) -> Config {
@@ -39,7 +40,7 @@ fn download_ci_llvm() {
 
     let if_unchanged_config = parse("llvm.download-ci-llvm = \"if-unchanged\"");
     if if_unchanged_config.llvm_from_ci {
-        let has_changes = if_unchanged_config.has_changes_from_upstream(&["src/llvm-project"]);
+        let has_changes = if_unchanged_config.has_changes_from_upstream(LLVM_INVALIDATION_PATHS);
 
         assert!(
             !has_changes,