From a288a5ea06bc601802e2f1537f883cb9019a2078 Mon Sep 17 00:00:00 2001
From: Andrew Chin <achin@eminence32.net>
Date: Wed, 15 Jan 2020 12:05:18 -0500
Subject: [PATCH] Store nightly snapshot in rust-toolchain file, and use it in
 cargo.sh

The rust-toolchain file can also store an exact nightly snapshot
(instead of just "nightly"), so we can store whatever snapshot that
rustc_codegen_cranelift is known to work with.

This also lets us add a new feature to `cargo.sh` to let it use the
exact same nightly snapshot as cg_clif.  If there's a nightly compiler
mismatch, you get a confusing error message like:

    error: couldn't load codegen backend "librustc_codegen_cranelift.so":
    "librustc_driver-681e2b4f66c73d3e.so: cannot open
    shared object file: No such file or directory"

So doing this automatically in cargo.sh is useful.
---
 cargo.sh       | 6 +++++-
 rust-toolchain | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/cargo.sh b/cargo.sh
index 42c137030a5d..5af238121519 100755
--- a/cargo.sh
+++ b/cargo.sh
@@ -6,9 +6,13 @@ fi
 
 pushd $(dirname "$0") >/dev/null
 source config.sh
+
+# read nightly compiler from rust-toolchain file
+TOOLCHAIN=$(cat rust-toolchain)
+
 popd >/dev/null
 
 cmd=$1
 shift
 
-cargo $cmd --target $TARGET_TRIPLE $@
+cargo +${TOOLCHAIN} $cmd --target $TARGET_TRIPLE $@
diff --git a/rust-toolchain b/rust-toolchain
index bf867e0ae5b6..ae478dbcb74e 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-nightly
+nightly-2020-01-13