From e993e6234181b0cc90b2aaa92ffbad4ea5b6a4da Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Fri, 23 Mar 2018 19:55:41 +0100
Subject: [PATCH] Use the same RUSTFLAGS for building and testing `bootstrap`

Fixes #49215
---
 src/bootstrap/test.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index d5c837c1274..5da4a8a4507 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -1679,6 +1679,12 @@ impl Step for Bootstrap {
            .env("CARGO_TARGET_DIR", build.out.join("bootstrap"))
            .env("RUSTC_BOOTSTRAP", "1")
            .env("RUSTC", &build.initial_rustc);
+        if let Some(flags) = option_env!("RUSTFLAGS") {
+            // Use the same rustc flags for testing as for "normal" compilation,
+            // so that Cargo doesn’t recompile the entire dependency graph every time:
+            // https://github.com/rust-lang/rust/issues/49215
+            cmd.env("RUSTFLAGS", flags);
+        }
         if !build.fail_fast {
             cmd.arg("--no-fail-fast");
         }