#!/bin/bash
set -e
# Manages a rustup toolchain called "miri".
#
# All commands set "miri" as the override toolchain for the current directory,
# and make the `rust-version` file match that toolchain.
#
# USAGE:
#
# ./rustup-toolchain: Update "miri" toolchain to match `rust-version` (the known-good version for this commit).
# 
# ./rustup-toolchain HEAD: Update "miri" toolchain and `rust-version` file to latest rustc HEAD.
# 
# ./rustup-toolchain $COMMIT: Update "miri" toolchain and `rust-version` file to match that commit.

# Make sure rustup-toolchain-install-master is installed.
if ! which rustup-toolchain-install-master >/dev/null; then
    echo "Please install rustup-toolchain-install-master by running 'cargo install rustup-toolchain-install-master'"
    exit 1
fi

# Determine new commit.
if [[ "$1" == "" ]]; then
    NEW_COMMIT=$(cat rust-version)
elif [[ "$1" == "HEAD" ]]; then
    NEW_COMMIT=$(git ls-remote https://github.com/rust-lang/rust/ HEAD | cut -f 1)
else
    NEW_COMMIT="$1"
fi
echo "$NEW_COMMIT" > rust-version

# Check if we already are at that commit.
CUR_COMMIT=$(rustc +miri --version -v | egrep "^commit-hash: " | cut -d " " -f 2)
if [[ "$CUR_COMMIT" == "$NEW_COMMIT" ]]; then
    echo "miri toolchain is already at commit $CUR_COMMIT."
    rustup override set miri
    exit 0
fi

# Cleanup.
cargo +nightly clean # Use nightly cargo as miri toolchain might be broken.
rustup toolchain uninstall miri

# Install and setup new toolchain.
rustup-toolchain-install-master -n miri -c rust-src -c rustc-dev -- "$NEW_COMMIT"
rustup override set miri