Bazel 使用 ccache 构建 C++ 示例失败答案

【问题标题】：Bazel building C++ sample with ccache failsBazel 使用 ccache 构建 C++ 示例失败
【发布时间】：2018-11-24 07:37:53
【问题描述】：

我一直按照 OSX here 的说明进行操作。我已经安装了 bazel，克隆了示例并尝试使用 bazel build //main:hello-world 构建它。但是这里出错了。

INFO: Analysed target //main:hello-world (0 packages loaded). INFO:
Found 1 target... ERROR:
/Users/myuser/work/temp/bazel-sample/examples/cpp-tutorial/stage1/main/BUILD:1:1:
Linking of rule '//main:hello-world' failed (Exit 1) ccache: error:
Failed to create temporary file for
/Users/myuser/.ccache/6/stats.tmp: Operation not
permitted Target //main:hello-world failed to build Use
--verbose_failures to see the command lines of failed build steps. INFO: Elapsed time: 0.295s, Critical Path: 0.07s INFO: 0 processes.
FAILED: Build did NOT complete successfully

似乎我安装的 ccache 存在问题。使用--verbose_failures 运行相同的命令后

INFO: Analysed target //main:hello-world (0 packages loaded). INFO:
Found 1 target... ERROR:
/Users/myuser/work/temp/bazel-sample/examples/cpp-tutorial/stage1/main/BUILD:1:1:
Linking of rule '//main:hello-world' failed (Exit 1): cc_wrapper.sh
failed: error executing command    (cd
/private/var/tmp/_bazel_myuser/550c05da61518b4bbbb0ffdfd033154f/execroot/__main__
&& \   exec env - \
    APPLE_SDK_PLATFORM='' \
    APPLE_SDK_VERSION_OVERRIDE='' \
    PATH=/Users/myuser/Library/Android/sdk/platform-tools:/Users/myuser/Library/Android/sdk/tools:/Users/myuser/Library/Android/sdk/build-tools/25.0.0:/Users/myuser/Library/Android/ndk/android-ndk-r10c:/Applications/CMake.app/Contents/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/TeX/texbin:/Users/myuser/bin
\
    XCODE_VERSION_OVERRIDE=9.3.0 \   external/local_config_cc/cc_wrapper.sh -fobjc-link-runtime -Wl,-S -o
bazel-out/darwin-fastbuild/bin/main/hello-world
bazel-out/darwin-fastbuild/bin/main/_objs/hello-world/main/hello-world.o
-headerpad_max_install_names -lc++ -no-canonical-prefixes)

Use --sandbox_debug to see verbose messages from the sandbox ccache:
error: Failed to create temporary file for
/Users/myuser/.ccache/0/stats.tmp: Operation not permitted Target
//main:hello-world failed to build INFO: Elapsed time: 0.294s,
Critical Path: 0.07s INFO: 0 processes. FAILED: Build did NOT complete
successfully

我发现沙盒存在问题。添加--sandbox_debug 打印：

INFO: Analysed target //main:hello-world (0 packages loaded).
INFO: Found 1 target...
ERROR: /Users/myuser/work/temp/bazel-sample/examples/cpp-tutorial/stage1/main/BUILD:1:1: Linking of rule '//main:hello-world' failed (Exit 1): sandbox-exec failed: error executing command 
  (cd /private/var/tmp/_bazel_myuser/550c05da61518b4bbbb0ffdfd033154f/execroot/__main__ && \
  exec env - \
    APPLE_SDK_PLATFORM='' \
    APPLE_SDK_VERSION_OVERRIDE='' \
    DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer \
    PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/myuser/bin \
    SDKROOT=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk \
    TMPDIR=/var/folders/x3/r5tf7wfx3_q0xnyx95s3r5400000gq/T/ \
    XCODE_VERSION_OVERRIDE=9.3.0 \
  /usr/bin/sandbox-exec -f /private/var/tmp/_bazel_myuser/550c05da61518b4bbbb0ffdfd033154f/sandbox/darwin-sandbox/1/sandbox.sb /private/var/tmp/_bazel_myuser/550c05da61518b4bbbb0ffdfd033154f/execroot/__main__/_bin/process-wrapper '--timeout=0' '--kill_delay=15' external/local_config_cc/cc_wrapper.sh -fobjc-link-runtime -Wl,-S -o bazel-out/darwin-fastbuild/bin/main/hello-world bazel-out/darwin-fastbuild/bin/main/_objs/hello-world/main/hello-world.o -headerpad_max_install_names -lc++ -no-canonical-prefixes)
ccache: error: Failed to create temporary file for /Users/myuser/.ccache/b/stats.tmp: Operation not permitted
Target //main:hello-world failed to build
INFO: Elapsed time: 0.268s, Critical Path: 0.06s
INFO: 0 processes.
FAILED: Build did NOT complete successfully

沙盒文件sandbox.sb的内容是：

(version 1)
(debug deny)
(allow default)
(deny file-write*)
(allow file-write*
    (subpath "/dev")
    (subpath "/Users/myuser/Library/Logs")
    (subpath "/Users/myuser/Library/Developer")
    (subpath "/private/var/folders/x3/r5tf7wfx3_q0xnyx95s3r5400000gq/T")
    (subpath "/private/var/tmp/_bazel_myuser/550c05da61518b4bbbb0ffdfd033154f/sandbox/darwin-sandbox/1/execroot/__main__")
    (subpath "/private/var/tmp")
    (subpath "/private/var/folders/x3/r5tf7wfx3_q0xnyx95s3r5400000gq/C")
    (subpath "/private/tmp")
)

显然缺少写入/Users/myuser/.ccache 目录的权限。我尝试使用 export CCACHE_DISABLE=1 禁用 ccache，但没有任何变化。如何在不删除 ccache 的情况下修复它？

【问题讨论】：

主目录将在沙箱中可用，但只读。如果您必须使用 .ccache （并跳出构建树进行编写），则必须禁用沙盒...但我想知道，您为什么不将缓存留给 bazel？
我可能应该。但是我的 ccache 正在替换 clang，并且 gcc 带有指向 self 的符号链接，并动态决定使用什么
好吧，如果你真的必须...有--sandbox_writable_path 选项。或者个别规则可以使用no-sandbox 标签，或者您可以使用--spawn_strategy=standalone 整体禁用它。但是...我仍然建议不要使用所有这些。 ;)

标签： c++ bazel ccache

【解决方案1】：

设置编译器的绝对路径并将其传递给CC 环境变量是一个选项吗？如果您安装了 Xcode，您可能需要使用 BAZEL_USE_CPP_ONLY_TOOLCHAIN=1。

【讨论】：

【解决方案2】：

export CC=/usr/bin/clang
export CXX=/usr/bin/clang++
<your bazel command>

可以用gcc替换clang

【讨论】：