From 25f321c628b3105aa25b8644876eb3f6452f5c6f Mon Sep 17 00:00:00 2001
From: Kornel <kornel@geekhood.net>
Date: Sun, 10 Dec 2017 21:25:52 +0000
Subject: [PATCH] Prevent RUSTFLAGS from breaking probing

Fixes #4761
---
 src/cargo/ops/cargo_rustc/context.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/cargo/ops/cargo_rustc/context.rs b/src/cargo/ops/cargo_rustc/context.rs
index 44b6cbb9a94..b3be8f1f63e 100644
--- a/src/cargo/ops/cargo_rustc/context.rs
+++ b/src/cargo/ops/cargo_rustc/context.rs
@@ -292,11 +292,14 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
                               crate_types: &BTreeSet<String>,
                               kind: Kind)
                               -> CargoResult<()> {
-        let rustflags = env_args(self.config,
+        let mut rustflags = env_args(self.config,
                                  &self.build_config,
                                  self.info(&kind),
                                  kind,
                                  "RUSTFLAGS")?;
+        // Any other output will confuse parsing
+        rustflags.retain(|arg| !arg.starts_with("--print="));
+
         let mut process = self.config.rustc()?.process();
         process.arg("-")
                .arg("--crate-name").arg("___")