From b3f369d9252e4c0d5dd9bd28b950c7730fcd2c3d Mon Sep 17 00:00:00 2001
From: Haowei Wu <haowei@google.com>
Date: Thu, 17 Jul 2025 16:12:28 -0700
Subject: [PATCH] Address some rustc inconsistency issues

We noticed when building rustc multiple time in a roll, some files
will not be consistent across the build despite the fact that they
are built from same source under the same environment. This patch
addresses the inconsistency issue we found on libunwind.a by sorting
the order of the files passed to the linker.
---
 src/bootstrap/src/core/build_steps/compile.rs | 10 +++++++---
 src/bootstrap/src/core/build_steps/llvm.rs    |  8 ++++++--
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index 09bb2e35bdaa2..11a5554691db8 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -2376,15 +2376,19 @@ pub fn run_cargo(
     let mut deps = Vec::new();
     let mut toplevel = Vec::new();
     let ok = stream_cargo(builder, cargo, tail_args, &mut |msg| {
-        let (filenames, crate_types) = match msg {
+        let (filenames_vec, crate_types) = match msg {
             CargoMessage::CompilerArtifact {
                 filenames,
                 target: CargoTarget { crate_types },
                 ..
-            } => (filenames, crate_types),
+            } => {
+                let mut f: Vec<String> = filenames.into_iter().map(|s| s.into_owned()).collect();
+                f.sort(); // Sort the filenames
+                (f, crate_types)
+            }
             _ => return,
         };
-        for filename in filenames {
+        for filename in filenames_vec {
             // Skip files like executables
             let mut keep = false;
             if filename.ends_with(".lib")
diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
index b2056f5cf3786..721ba6ca459e4 100644
--- a/src/bootstrap/src/core/build_steps/llvm.rs
+++ b/src/bootstrap/src/core/build_steps/llvm.rs
@@ -1528,8 +1528,12 @@ impl Step for Libunwind {
 
         // FIXME: https://github.com/alexcrichton/cc-rs/issues/545#issuecomment-679242845
         let mut count = 0;
-        for entry in fs::read_dir(&out_dir).unwrap() {
-            let file = entry.unwrap().path().canonicalize().unwrap();
+        let mut files = fs::read_dir(&out_dir)
+            .unwrap()
+            .map(|entry| entry.unwrap().path().canonicalize().unwrap())
+            .collect::<Vec<_>>();
+        files.sort();
+        for file in files {
             if file.is_file() && file.extension() == Some(OsStr::new("o")) {
                 // Object file name without the hash prefix is "Unwind-EHABI", "Unwind-seh" or "libunwind".
                 let base_name = unhashed_basename(&file);