Ensure correct toolchain per clone. (#6054)

Previously, if the Rust toolchain was changed, re-bootstrapping would
proceed correctly in the first clone encountering the change but it
would fail in other clones. Ensure the correct toolchain is set when
building the symlink farm (but not needing to bootstrap the toolchain)
to cover this case.

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: