包含Bazel下載的文件http_file

Question

我正在使用Bazel構建我的項目。 我想使用單頭測試框架Catch v2 。 我決定使用http_file規則使Bazel下載catch標頭。 我的WORKSPACE文件如下所示：

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_file")

http_file(
  name = "catch",
  downloaded_file_path = "catch.hpp",
  sha256 = "cc6cc272cf84d8e10fb28f66f52584dedbb80d1234aae69e6a1027af4f31ae6f",
  urls = ["https://github.com/catchorg/Catch2/releases/download/v2.4.2/catch.hpp"],
)

根據文檔，測試取決於生成的軟件包，如下所示：

cc_test(
  name = "my_test",
  srcs = ["@catch//file", "my_test.cc"]
)

測試文件my_test.cc不能再簡單了：

#include "catch.hpp"

但是，出現以下錯誤：

$ bazel test --config=opt -s //...
WARNING: [...]/BUILD:25:10: in srcs attribute of cc_test rule //test:my_test: please do not import '@catch//file:catch.hpp' directly. You should either move the file to this package or depend on an appropriate rule there
SUBCOMMAND: # //test:my_test [action 'Compiling test/my_test.cc']
(cd [...] && \
  exec env - [...] \
  /usr/bin/gcc
 -U_FORTIFY_SOURCE -fstack-protector -Wall -B/usr/bin -B/usr/bin -Wunused-but-set-parameter -Wno-free-nonheap-object -fno-omit-frame-pointer '-std=c++0x' -MD -MF [...].d '-frandom-seed=[...].o' -fPIC
 -iquote .
 -iquote bazel-out/k8-fastbuild/genfiles
 -iquote bazel-out/k8-fastbuild/bin
 -iquote external/bazel_tools
 -iquote bazel-out/k8-fastbuild/genfiles/external/bazel_tools
 -iquote bazel-out/k8-fastbuild/bin/external/bazel_tools
 -fno-canonical-system-headers -Wno-builtin-macro-redefined '-D__DATE__="redacted"' '-D__TIMESTAMP__="redacted"' '-D__TIME__="redacted"' -c test/my_test.cc
 -o [...].o)
ERROR: [...]/BUILD:23:1: C++ compilation of rule '//test:my_test' failed (Exit 1)
test/my_test.cc:1:28: fatal error: catch.hpp: No such file or directory
compilation terminated.
[...]
FAILED: Build did NOT complete successfully

創建cc_library包裝器或包含catch/catch.hpp ，catch / file / catch.hpp會產生相同的錯誤。

Answer 1

默認情況下， http_file下載的文件可以包含為：

#include "external/<name>/file/<file_name>"

在這種情況下：

#include "external/catch/file/catch.hpp"

但是，此包含路徑很難看，應該用cc_library包裝。 此外，為每個測試編譯完整的catch頭文件將使構建變慢。 根據catch文檔 ，catch標頭的實現部分應單獨編譯。 像這樣：

測試/ BUILD：

cc_library(
  name = "catch",
  hdrs = ["@catch//file"],
  srcs = ["catch.cpp"],
  visibility = ["//visibility:public"],
  strip_include_prefix = "/external/catch/file",
  include_prefix = "catch",
  linkstatic = True,   # otherwise main() will could end up in a .so
)

cc_test(
  name = "my_test",
  deps = ["//test:catch"],
  srcs = ["my_test.cc"],
)

測試/ catch.cpp：

#define CATCH_CONFIG_MAIN
#include "catch/catch.hpp"

測試/ my_test.cc：

#include "catch/catch.hpp"

TEST_CASE("my_test", "[main]") { /* ... */ }

如果只更改catch.cpp將不會重新編譯my_test.cc ，從而節省了寶貴的時間。