all commands: use /tmp/bazel-zig-cc (#6)

Different Bazel instances can share the zig cache all right.

.bazelrc

@@ -7,5 +7,3 @@ build --worker_sandboxing
 build --experimental_reuse_sandbox_directories
 build --incompatible_enable_cc_toolchain_resolution
 build --action_env BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1
-
-try-import %workspace%/.custom.ci.bazelrc

.buildkite/pipeline.yml

@@ -3,15 +3,11 @@
 
 steps:
   - label: "Test"
-    command: |
+    command: ci/test
-      . .buildkite/setup-bazelrc.sh
-      ci/test
   - label: "Lint"
-    command: |
+    command: ci/lint
-      . .buildkite/setup-bazelrc.sh
-      ci/lint
   - label: "List Platforms"
-    command: "ci/list_toolchains_platforms"
+    command: ci/list_toolchains_platforms
   - label: "Test Release and Launcher scripts"
     command: |
       git config --global user.email "buildkite@example.com"
@@ -31,7 +27,6 @@ steps:
       ci/launcher-wine64
   - label: "mod-tidy and update-repos"
     command: |
-      . .buildkite/setup-bazelrc.sh
       bin/mod-tidy
       git diff --exit-code
 agents:

.buildkite/setup-bazelrc.sh

@@ -1,15 +0,0 @@
-# Copyright 2023 Uber Technologies, Inc.
-# Licensed under the Apache License, Version 2.0
-
-if [ -z "${BUILDKITE_BUILD_NUMBER:-}" ]; then
-    >&2 echo "error: expected to run in buildkite"
-    exit 1
-fi
-
-export BAZEL_ZIG_CC_CACHE_PREFIX="/tmp/bazel-zig-cc${BUILDKITE_BUILD_NUMBER}"
-mkdir -p "$BAZEL_ZIG_CC_CACHE_PREFIX"
-
-cat > .custom.ci.bazelrc <<EOF
-common --repo_env BAZEL_ZIG_CC_CACHE_PREFIX="$BAZEL_ZIG_CC_CACHE_PREFIX"
-build --sandbox_writable_path "$BAZEL_ZIG_CC_CACHE_PREFIX"
-EOF

bin/mod-tidy

@@ -4,7 +4,7 @@
 # Licensed under the Apache License, Version 2.0
 set -xeu
 
-cd "$(git rev-parse --show-toplevel)/"
+cd "$(git rev-parse --show-toplevel)"
 echo "--- go mod tidy"
 tools/bazel run @go_sdk//:bin/go -- mod tidy
 

ci/lint

@@ -7,7 +7,6 @@ set -euo pipefail
 
 cd "$(git rev-parse --show-toplevel)"
 
-
 if command -v shellcheck &> /dev/null; then
     mapfile -t files < \
         <(git ls-files)

ci/test

@@ -5,22 +5,26 @@
 
 set -xeuo pipefail
 
+cache_prefix="${BAZEL_ZIG_CC_CACHE_PREFIX:-/tmp/bazel-zig-cc}"
+
 # check a very hermetic setup with a single target. Re-building all of
 # them takes a long time, so using only one. If we ever decide to build all
 # targets, we will need to exclude Go, since go dynamically links to glibc on
 # linux.
+
 echo "--- build a single target with very hermetic sandbox"
 tools/bazel build "$@" \
     --experimental_use_hermetic_linux_sandbox \
+    --sandbox_writable_path="$cache_prefix" \
     --sandbox_add_mount_pair=/proc \
     //test/c:which_libc_linux_amd64_gnu.2.19
 
 # then test everything else with the standard sandbox
-echo "--- bazel test $@ ..."
+echo "--- bazel test $* ..."
 tools/bazel test "$@" ...
 
 echo "--- ensure github.com/ziglang/zig/issues/13050 does not regress"
-find "${BAZEL_ZIG_CC_CACHE_PREFIX:-/tmp/bazel-zig-cc}" \
+find "$cache_prefix" \
     -name mutex_destructor.o -execdir file '{}' \; \
     | sort \
     | uniq -c \