From: Jakub Jirutka <jakub@jirutka.cz>
Date: Sat, 08 Aug 2016 19:56:00 +0200
Subject: [PATCH] Change rpath for rustc/rustdoc to rustlib/$TARGET/lib

Rust installs two identical sets of *.so libraries into /usr/lib and
/usr/lib/rustlib/$TARGET/lib. The former comes with the rustc component,
/usr/bin/rustc and /usr/bin/rustdoc are linked against them. The latter
comes with rust-std and are used for binaries dynamically linked against
Rust libraries (usually compiler plugins, like clippy).

These *.so libraries don't keep stable ABI, so it's better to treat
them as private. Such libraries should not be exposed at standard paths
like /usr/lib, but use rpath.

This patch changes rpath for binaries of the rustc component to
`$ORIGIN/../lib/rustlib/$TARGET/lib`. Duplicate libraries will be still
installed into /usr/lib, but we can simply remove them when packaging.

Related upstream issues:

* https://github.com/rust-lang/rust/issues/37971
* https://github.com/rust-lang-nursery/rustup.rs/issues/837

--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -189,9 +189,9 @@
                 if stage != "0" {
                     cmd.arg("-Z").arg("osx-rpath-install-name");
                 }
-                Some("-Wl,-rpath,@loader_path/../lib")
+                Some("-Wl,-rpath,@loader_path/../lib".to_string())
             } else if !target.contains("windows") {
-                Some("-Wl,-rpath,$ORIGIN/../lib")
+                Some(format!("-Wl,-rpath,$ORIGIN/../lib/rustlib/{}/lib", target))
             } else {
                 None
             };