我几天前才开始使用Bazel，希望它能比CMake更好。我有一个小库，它在自己的存储库中只包含protobuf定义。我已经得到了bazel构建原型，并在bazel-bin/proto目录中看到它们，但我不确定如何继续使该目录包含在依赖的工作区/包中，以便我可以利用输出头文件?
proto-repo:构建
load("@rules_cc//cc:defs.bzl", "cc_proto_library")
load("@rules_proto//proto:defs.bzl", "proto_library")
cc_library(
name = "my-protobuf-common",
hdrs = [
":my-proto-lib",
],
copts = ["--std=c++17"],
includes = [
":my-proto-lib",
],
linkstatic = True,
visibility = ["//visibility:public"],
deps = [":my-proto-lib"],
)
cc_proto_library(
name = "my-proto-lib",
visibility = ["//visibility:public"],
deps = [":my-proto"],
)
proto_library(
name = "my-proto",
srcs = [
"proto/point.proto",
"proto/point-geodetic.proto",
"proto/point-ned.proto",
],
visibility = ["//visibility:public"],
)
依赖的repo(工作空间正确拉为外部，我看到原型构建输出):构建
load("@rules_cc//cc:defs.bzl", "cc_library")
cc_library(
name = "my-service",
srcs = [
"app/bazel-test.cpp",
],
hdrs = [
"@mpc//:my-protobuf-common",
],
copts = ["--std=c++17"],
deps = [
"@mpc//:my-protobuf-common",
],
)
bazel-test.cpp
#include <iostream>
#include <proto/point.pb.h>
int main() {
MyProtobufCommon::Point p;
}
构建错误:
app/bazel-test.cpp:2:10: fatal error: proto/point.pb.h: No such file or directory
2 | #include <proto/point.pb.h>
| ^~~~~~~~~~~~~~~~~~
一般来说，您应该能够直接依赖cc_proto_library，因此通常不需要中间的cc_librarymy-protobuf-common。cc工具链使用-iquote来添加原型深度，所以我认为必须使用#include "proto/point.pb.h"。
proto-repo/WORKSPACE:
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
name = "rules_proto",
sha256 = "66bfdf8782796239d3875d37e7de19b1d94301e8972b3cbd2446b332429b4df1",
strip_prefix = "rules_proto-4.0.0",
urls = [
"https://mirror.bazel.build/github.com/bazelbuild/rules_proto/archive/refs/tags/4.0.0.tar.gz",
"https://github.com/bazelbuild/rules_proto/archive/refs/tags/4.0.0.tar.gz",
],
)
load("@rules_proto//proto:repositories.bzl", "rules_proto_dependencies", "rules_proto_toolchains")
rules_proto_dependencies()
rules_proto_toolchains()
proto-repo/BUILD:
cc_proto_library(
name = "point_cc_proto",
deps = [":point"],
visibility = ["//visibility:public"],
)
proto_library(
name = "point",
srcs = ["proto/point.proto"],
)
proto-repo/proto/point.proto:
syntax = "proto3";
package my_protos.point;
message Point {
optional int32 x = 1;
optional int32 y = 2;
}
main-repo/WORKSPACE:
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
local_repository(
name = "my_protos",
path = "../proto-repo",
)
http_archive(
name = "rules_proto",
sha256 = "66bfdf8782796239d3875d37e7de19b1d94301e8972b3cbd2446b332429b4df1",
strip_prefix = "rules_proto-4.0.0",
urls = [
"https://mirror.bazel.build/github.com/bazelbuild/rules_proto/archive/refs/tags/4.0.0.tar.gz",
"https://github.com/bazelbuild/rules_proto/archive/refs/tags/4.0.0.tar.gz",
],
)
load("@rules_proto//proto:repositories.bzl", "rules_proto_dependencies", "rules_proto_toolchains")
rules_proto_dependencies()
rules_proto_toolchains()
main-repo/BUILD:
cc_binary(
name = "main",
srcs = ["main.cc"],
deps = ["@my_protos//:point_cc_proto"],
)
main-repo/main.cc:
#include <iostream>
#include "proto/point.pb.h"
int main() {
my_protos::point::Point p;
p.set_x(123);
p.set_y(456);
std::cout << p.DebugString();
return 0;
}
用法:
main-repo$ bazel run main
INFO: Analyzed target //:main (43 packages loaded, 570 targets configured).
INFO: Found 1 target...
Target //:main up-to-date:
bazel-bin/main
INFO: Elapsed time: 6.166s, Critical Path: 5.33s
INFO: 106 processes: 4 internal, 102 linux-sandbox.
INFO: Build completed successfully, 106 total actions
INFO: Build completed successfully, 106 total actions
x: 123
y: 456
cc_library.includes接受表示路径的字符串，而不是标签。
my-protobuf-common中设置includes = ["."]。同样，cc_library.hdrs是头文件的源文件，它的目标依赖于#include。同时列出deps和hdrs中的内容是没有意义的，对于这个用例，您根本不需要hdrs。
同样，使用cc_binary来构建带有main的文件。cc_library不做完整的链接。
此外，copts = ["--std=c++17"]很少是一个好主意。这只为该cc_library中的文件设置标志，它可以更改其ABI，以便链接到构建的其他部分不起作用。在这种情况下，cc_proto_library的cc_library等同部分将无法通过标志。使用bazel命令行标志--copt=--std=c++17 instead将其应用于整个构建。