Ensure correct toolchain per clone.

build-support/bin/native/bootstrap_rust.sh

@@ -7,7 +7,7 @@ REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")" && cd ../../.. && pwd -P)"
 # + fingerprint_data: Fingerprints the data on stdin.
 source "${REPO_ROOT}/build-support/common.sh"
 
-readonly RUST_TOOLCHAIN="1.27.0"
+RUST_TOOLCHAIN="$(cat ${REPO_ROOT}/rust-toolchain)"
 readonly RUST_COMPONENTS=(
   "rustfmt-preview"
   "rust-src"
@@ -23,7 +23,7 @@ function cargo_bin() {
   "${RUSTUP}" which cargo
 }
 
-function ensure_native_build_prerequisites() {
+function bootstrap_rust() {
   # Control a pants-specific rust toolchain.
   if [[ ! -x "${RUSTUP}" ]]
   then
@@ -32,7 +32,7 @@ function ensure_native_build_prerequisites() {
     local -r rustup_tmp=$(mktemp -t pants.rustup.XXXXXX)
     curl https://sh.rustup.rs -sSf > ${rustup_tmp}
     # NB: rustup installs itself into CARGO_HOME, but fetches toolchains into RUSTUP_HOME.
-    sh ${rustup_tmp} -y --no-modify-path --default-toolchain "${RUST_TOOLCHAIN}" 1>&2
+    sh ${rustup_tmp} -y --no-modify-path --default-toolchain none 1>&2
     rm -f ${rustup_tmp}
   fi
 
@@ -41,11 +41,11 @@ function ensure_native_build_prerequisites() {
   local -r cargo_versioned="cargo-${RUST_TOOLCHAIN}-${cargo_components_fp}"
   if [[ ! -x "${rust_toolchain_root}/${cargo_versioned}" ]]
   then
-    (
-      cd "${REPO_ROOT}"
-      "${RUSTUP}" override set "${RUST_TOOLCHAIN}" >&2
-    )
-    "${RUSTUP}" component add ${RUST_COMPONENTS[@]} >&2
+    # If rustup was already bootstrapped against a different toolchain in the past, freshen it and
+    # ensure the toolchain and components we need are installed.
+    "${RUSTUP}" self update
+    "${RUSTUP}" toolchain install ${RUST_TOOLCHAIN}
+    "${RUSTUP}" component add --toolchain ${RUST_TOOLCHAIN} ${RUST_COMPONENTS[@]} >&2
 
     ln -fs "$(cargo_bin)" "${rust_toolchain_root}/${cargo_versioned}"
   fi

build-support/bin/native/cargo.sh

@@ -7,10 +7,9 @@ REPO_ROOT=$(cd $(dirname "${BASH_SOURCE[0]}") && cd ../../.. && pwd -P)
 # Exports:
 # + CARGO_HOME: The CARGO_HOME of the Pants-controlled rust toolchain.
 # Exposes:
-# + ensure_native_build_prerequisites: Bootstraps a Pants-controlled rust toolchain and associated
-#                                      extras.
+# + bootstrap_rust: Bootstraps a Pants-controlled rust toolchain and associated extras.
 source "${REPO_ROOT}/build-support/bin/native/bootstrap_rust.sh"
-ensure_native_build_prerequisites >&2
+bootstrap_rust >&2
 
 download_binary="${REPO_ROOT}/build-support/bin/download_binary.sh"
 

build-support/bin/native/rust_toolchain.sh

@@ -7,8 +7,7 @@ REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")" && cd ../../.. && pwd -P)"
 # Defines:
 # + CARGO_HOME: The CARGO_HOME of the Pants-controlled rust toolchain.
 # Exposes:
-# + ensure_native_build_prerequisites: Bootstraps a Pants-controlled rust toolchain and associated
-#                                      extras.
+# + bootstrap_rust: Bootstraps a Pants-controlled rust toolchain and associated extras.
 source "${REPO_ROOT}/build-support/bin/native/bootstrap_rust.sh"
 
 if [ ! -h $0 ]; then
@@ -20,5 +19,5 @@ EOF
 fi
 binary="$(basename "$0")"
 
-ensure_native_build_prerequisites >&2
+bootstrap_rust >&2
 exec "${CARGO_HOME}/bin/${binary}" "$@"

rust-toolchain

@@ -0,0 +1 @@
+1.27.0

tests/python/pants_test/pants_run_integration_test.py

@@ -447,9 +447,15 @@ def mock_buildroot(self, dirs_to_copy=None):
     # N.B. BUILD.tools, contrib, 3rdparty needs to be copied vs symlinked to avoid
     # symlink prefix check error in v1 and v2 engine.
     files_to_copy = ('BUILD.tools',)
-    files_to_link = ('pants', 'pants.ini', 'pants.travis-ci.ini', '.pants.d',
-                     'build-support', 'pants-plugins', 'src')
-    dirs_to_copy = ('contrib', '3rdparty') + tuple(dirs_to_copy or [])
+    files_to_link = ('.pants.d',
+                     'build-support',
+                     'pants',
+                     'pants-plugins',
+                     'pants.ini',
+                     'pants.travis-ci.ini',
+                     'rust-toolchain',
+                     'src')
+    dirs_to_copy = ('3rdparty', 'contrib') + tuple(dirs_to_copy or [])
 
     with self.temporary_workdir() as tmp_dir:
       for filename in files_to_copy: