Overhaul cargo/rustc version management

ci/rust-version.sh

@@ -0,0 +1,45 @@
+#
+# This file maintains the rust versions for use by CI.
+#
+# Build with stable rust, updating the stable toolchain if necessary:
+#   $ source ci/rust-version.sh stable
+#   $ cargo +"$rust_stable" build
+#
+# Build with nightly rust, updating the nightly toolchain if necessary:
+#   $ source ci/rust-version.sh nightly
+#   $ cargo +"$rust_nightly" build
+#
+# Obtain the environment variables without any automatic toolchain updating:
+#   $ source ci/rust-version.sh
+#
+
+export rust_stable=1.32.0
+export rust_stable_docker_image=solanalabs/rust:1.32.0
+
+export rust_nightly=nightly-2019-01-31
+export rust_nightly_docker_image=solanalabs/rust-nightly:2019-01-31
+
+[[ -z $1 ]] || (
+
+  rustup_install() {
+    declare toolchain=$1
+    if ! cargo +"$toolchain" -V; then
+      rustup install "$toolchain"
+      cargo +"$toolchain" -V
+    fi
+  }
+
+  set -e
+  cd "$(dirname "${BASH_SOURCE[0]}")"
+  case $1 in
+  stable)
+     rustup_install "$rust_stable"
+     ;;
+  nightly)
+     rustup_install "$rust_nightly"
+    ;;
+  *)
+    echo "Note: ignoring unknown argument: $1"
+    ;;
+  esac
+)