From 706fc559532f24e77d0f0c1319723848ed82eb67 Mon Sep 17 00:00:00 2001
From: Samuel Holland <samuel@sholland.org>
Date: Sat, 25 Feb 2017 23:30:10 -0600
Subject: [PATCH] Infer a default musl_root for native builds

---
 src/bootstrap/sanity.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index 245002019ef57..3ee11135165b8 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -159,6 +159,13 @@ pub fn check(build: &mut Build) {
 
         // Make sure musl-root is valid
         if target.contains("musl") {
+            // If this is a native target (host is also musl) and no musl-root is given,
+            // fall back to the system toolchain in /usr before giving up
+            if build.musl_root(target).is_none() && build.config.build == *target {
+                let target = build.config.target_config.entry(target.clone())
+                                 .or_insert(Default::default());
+                target.musl_root = Some("/usr".into());
+            }
             match build.musl_root(target) {
                 Some(root) => {
                     if fs::metadata(root.join("lib/libc.a")).is_err() {